Waid v. Snyder

E.D. Mich.9/9/2024
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Full Opinion

             UNITED STATES DISTRICT COURT                                
             EASTERN DISTRICT OF MICHIGAN                                
                    SOUTHERN DIVISION                                    


In re Flint Water Cases.         Judith E. Levy                          
                                 United States District Judge            
________________________________/                                        

This Order Relates To:                                                   

Bellwether III Cases                                                     
________________________________/                                        

OPINION AND ORDER GRANTING IN PART AND DENYING IN                         
PART DEFENDANTS VEOLIA NORTH AMERICA, LLC, VEOLIA                         
   NORTH AMERICA, INC., AND VEOLIA WATER NORTH                           
   AMERICA OPERATING SERVICES, LLC’S MOTION TO                           
   EXCLUDE OPINIONS AND TESTIMONY OF DR. AARON                           
                        SPECHT [2916]                                    
    Currently before the Court is Veolia North America, LLC, Veolia      
North  America,  Inc.,  and  Veolia  Water  North  America  Operating     
Services, LLC’s (“VNA”) Motion to Exclude Opinions and Testimony of       
Dr.  Aaron  Specht  (“the  Motion”).  (ECF  No.  2916.)  Bellwether  III  
Plaintiffs  Y.A.,  E.A.,  G.B.,  C.D.,  R.E.,  J.N.,  and  J.S.  (“Plaintiffs”  or 
“Bellwether III Plaintiffs”), who were all minor children at the time of the 
Flint water crisis, oppose the motion. (ECF No. 3013.) VNA replied to     
Plaintiffs’ submission. (ECF No. 3039.) For the reasons set forth below,  

the Motion is granted in part and denied in part.                         
    I.   Background                                                      
    The Court’s ruling on a similar motion from Bellwether I describes   
Dr. Specht as follows:                                                    

    Dr. Specht has a Ph.D. in medical physics and is a leading           
    expert on the use of portable x-ray fluorescence technology          
    (“pXRF”) to assess metal exposures. Dr. Specht has published         
    widely on the use of pXRF to measure bone-lead content in            
    adults, children, and animals. His qualifications as an expert       
    are not in dispute.                                                  

In re Flint Water Cases, No. 17-10164, 2021 WL 5356295, at *1 (E.D.       
Mich. Nov. 17, 2021) (“Specht I”). Dr. Specht is currently an assistant   
professor  of  health  sciences  at  Purdue  University.  (ECF  No.  3011-6, 
PageID.101811.)                                                           
    Plaintiffs retained Dr. Specht to evaluate their exposure to lead.   
(ECF No. 3013, PageID.101933.) Dr. Specht testifies that the best way to  
measure lead exposure over time is through bone lead testing. He states   

that blood lead testing, which is a standard technique, is “incredibly time 
sensitive”  and  only  captures  more  recent  exposures,  especially  for 


                               2                                         
children. (ECF No. 2913-31, PageID.97436–97437.) In Specht I, the Court   

set forth:                                                                
    Ordinarily  bone  lead  measurements  are  taken  by  a  large,      
    stationary “KXRF” device. It takes approximately 30 minutes          
    to get an accurate measurement using KXRF technology. Dr.            
    Specht  pioneered  the  use  of  the  alternative  pXRF  device.     
    Portable-XRF  and  KXRF  devices  measure  bone  lead  in            
    substantially the same way. (ECF No. 330-48, PageID.15629–           
    15630.) Both are applied to the subjects’ tibia bone, and both       
    generate  raw  spectral  data  which  is  then  processed  by  a     
    computer to generate a relevant measurement (in this case,           
    lead content) and an associated uncertainty value (the margin        
    of error). Portable-XRF devices are small, easily portable, and      
    require only 3 minutes to complete a measurement.                    

2021 WL 5356295, at *1. Based on bone lead testing using a pXRF device,   
Dr. Specht found that Plaintiffs were exposed to lead in varying amounts. 
(See, e.g., ECF No. 2913-31, PageID.97441.)                               
    In Specht I, the Court denied VNA’s motion to exclude Dr. Specht’s   
opinions, which was based on the following arguments:                     
    VNA argues that [Dr. Specht’s use of pXRF] is not [reliable],        
    primarily because (1) Dr. Specht’s own research shows pXRF           
    measurements of bone lead to be less reliable in pediatric than      
    in adult [subjects] (ECF No. 330-7, PageID.14445–14455), and         
    (2) the lack of bone lead measurements in healthy control            
    populations makes it impossible to assign any significance to        
    the measurements Dr. Specht obtained (Id. at PageID.14461–           
                               3                                         
    14474). VNA ultimately maintains that Dr. Specht’s use of            
    pXRF does not satisfy even a single Daubert factor.                  
    VNA further argues that Dr. Specht’s testimony should be             
    excluded under Federal Rules of Evidence 401(a), 402, and            
    403, because it is irrelevant and would be more prejudicial          
    than  probative.  (ECF  No.  330-7,  PageID.14475–14479.)            
    Finally, VNA asserts that Dr. Specht’s opinion regarding the         
    higher reliability of bone lead measurements when compared           
    to  blood  lead  measurements  is  unreliable  and  based  on        
    “cherry  picked”  studies.  (ECF  No.  330-7,  PageID.14480–         
    14481.)                                                              

2021 WL 5356295, at *3. Since the Bellwether I trial, the Court ordered   
Dr. Specht to provide VNA with the MATLAB code1 used for calibrating      
the pXRF device and for measuring lead content from the spectral data     
the  device  produces.  VNA  presents  new  objections  to  Dr.  Specht’s 
testimony based on their experts’ review of that code. (ECF No. 2913-3,   
PageID.96225.)                                                            
    The Court has already decided two rounds of Daubert motions in       
anticipation of the Bellwether I and the Issues Class trials, amounting to 



    1  Dr.  Specht  explains  that  “MATLAB  [code]  is  a  programming  platform 
designed specifically for engineers and scientists to analyze and design systems. The 
MATLAB language is a high-performance language for technical computing.” (ECF 
No. 3011-6, PageID.101781 n.1.) He uses MATLAB code to process the data generated 
by the pXRF device.                                                       
                               4                                         
seventeen  rulings  in  total.  It  also  considered  Daubert  challenges  to 

experts at the time it certified the Issues Class. See In re Flint Water  
Cases, 558  F.  Supp.  3d  459,  523–25  (E.D.  Mich.  2021)  (deciding  two 
Daubert motions out of over a dozen Daubert motions VNA filed at the      

class  certification  stage).  Additionally,  when  approving  the  partial 
settlement, the Court  denied objections to using the  pXRF  device  as   
evidence in the settlement. In re Flint Water Cases, 571 F. Supp. 3d 746, 

794–812  (E.D.  Mich.  2021).  Given  the  Court’s  familiarity  with  these 
experts, it ordered the Parties not to repeat arguments already made and  
instead  ordered  them  to  preserve  arguments  the  Court  had  already 

considered by reference to those arguments in earlier filings.2 (ECF No.  
2901, PageID.95084.)                                                      
    II.  Legal Standard                                                  

    Federal Rule of Evidence 702 governs the admissibility of expert     
testimony and requires that: (1) the witness must be qualified, (2) the   
testimony must be relevant, and (3) the testimony must be reliable. Fed.  

R. Evid. 702; In re Scrap Metal Antitrust Litig., 527 F.3d 517, 528–29 (6th 

    2  The  Court  has  also  already  ruled  on  seven  Daubert  motions  related  to 
Bellwether III. (See ECF Nos. 2959, 3007, 3034, 3043, 3078.)              
                               5                                         
Cir. 2008). As the Supreme Court explained in Daubert v. Merrell Dow      

Pharmaceuticals, Rule 702 imposes a “gatekeeping” obligation on the       
courts  to  ensure  that  scientific  testimony  “is  not  only  relevant,  but 
reliable.” 509  U.S.  579,  589  (1993);  see  also Kumho Tire Co.,  Ltd.  v. 

Carmichael, 526 U.S. 137, 147 (1999).                                     
    In Daubert, the Supreme Court provided a non-exclusive list of       
factors courts may consider when evaluating reliability: (1) whether the  

theory or technique at the basis of the opinion is testable or has been   
tested, (2) whether it has been published and subjected to peer review,   
(3) what the known error rates are and whether there are standards        

controlling  the  technique’s  operation,  and  (4)  whether  the  theory  or 
technique is generally accepted. Daubert, 509 U.S. at 593; see also In re 
Scrap Metal, 527 F.3d at 529 (listing same factors). Not every factor     

needs to be present in every instance, and courts may adapt them as       
appropriate for the facts of an individual case. Kumho, 526 U.S. at 150.  
    “Rejection of expert testimony is the exception, rather than the     

rule.”  United  States  v.  LaVictor,  848  F.3d  428,  442  (6th  Cir.  2017) 
(quoting In re Scrap Metal, 527 F.3d at 529–30)). The burden is on the    
proponent of the testimony to show by a “preponderance of proof” that     

                               6                                         
the proffered expert meets the standards of Rule 702 as interpreted by    

Daubert. Pride v. BIC Corp., 218 F.3d 566, 578 (6th Cir. 2000) (quoting   
Daubert, 509 U.S. at 592).                                                
    Under Rule 403, the Court “may exclude relevant evidence if its      

probative value is substantially outweighed by a danger of one or more of 
the following: unfair prejudice, confusing the issues, misleading the jury, 
undue  delay,  wasting  time,  or  needlessly  presenting  cumulative     

evidence.” Fed. R. Evid. 403.                                             
    III.  Analysis                                                       
    VNA  argues  that  Dr.  Specht’s  “report  and  opinions  should  be 

excluded because his MATLAB code has not been shown to accurately         
measure  low  levels  of  lead  in  children’s  bones.”  (ECF  No.  2913-3, 
PageID.96233.) It also argues that the Court should exclude Dr. Specht’s  

estimate of bone lead half-life and related opinions, because they are    
unreliable and more prejudicial than probative. (Id. at PageID.96246.)    
      A.  Reliability                                                    

    VNA asserts that Dr. Specht’s opinions should be excluded because    
his MATLAB code has not been subject to peer review and publication, it   
has high error rates, it has not been tested to verify its ability to detect 

                               7                                         
low bone lead levels in children, and it is not generally accepted by the 

scientific  community.  These  arguments  based  on  reliability  do  not 
support the exclusion of Dr. Specht’s opinions.                           
         i.   Peer Review                                                

    Because Dr. Specht’s MATLAB code has not been subject to peer        
review and publication, VNA argues that it lacks “any indicia of scientific 
reliability.” (ECF No. 2913-3, PageID.96234.) VNA argues that only Dr.    

Specht and a VNA expert, Dr. William Huber, have seen the MATLAB          
code, including Dr. Specht’s collaborators and the peer reviewers for his 
published articles. (Id.)                                                 

    Peer review—including publication in a peer-reviewed journal—is      
considered under Rule 702 and Daubert, because it is a “measure of        
reliability” indicating that an opinion has been “submitted to the scrutiny 

of the scientific community.” United States v. Gissantaner, 990 F.3d 457, 
464 (6th Cir. 2021) (quotation omitted). In Daubert, the Court explains   
that “[t]he fact of publication (or lack thereof) in a peer reviewed journal 

thus will be a relevant, though not dispositive, consideration in assessing 
the scientific validity of a particular technique or methodology on which 
an opinion is premised.” 509 U.S. at 594.                                 

                               8                                         
    VNA argues that the peer review factor in the Daubert analysis       

weighs against admission, in part because no one except for Dr. Specht    
and Dr. Huber has tested the MATLAB code used to measure bone lead        
levels  in  this  litigation.  (ECF  No.  2913-3,  PageID.96234.)  Plaintiffs 

respond that parts of the MATLAB code have been reviewed by and relied    
upon by other researchers. (ECF No. 3013, PageID.101940.) Dr. Specht,     
in a declaration, states that “the framework” for the relevant MATLAB     

code has been shared with other researchers, some of whom use similar     
code in their published work. (ECF No. 3011-6, PageID.101781.) While      
Dr. Specht acknowledges that not every aspect of the code used in his     

work in Flint has been shared, he asserts that the parts that have been   
shared relate to “lead levels and uncertainty levels,” which is precisely 
what VNA challenges. (Id. at PageID.101782; see also ECF No. 3011-7,      

PageID.101839.) He explains:                                              
    The [] specific parts of the code [used in the Flint Water Cases]    
    have  nothing  to  do  with  the  methodology  challenged  by        
    [VNA’s experts] Dr. Huber and Dr. [Lambertus] Hesselink.             
    Rather, the parts of the code that are Flint specific are related    
    to instrument specific (meaning the specific pXRF being used)        
    numbers, related to the calibration of the instrument, and not       
    my methodology. In other words, the only parts of the code           
    that  are  unique  are  the  portions  of  the  code  related  to    
                               9                                         
    calibrating  the  actual  pXRF  being  used.  Meanwhile,  the        
    underlying methodology that the MATLAB code is applying              
    to calculate lead levels and uncertainty values is the same          
    across all devices.                                                  

(ECF No. 3011-6, PageID.101784.) That is, according to Dr. Specht, the    
disputed part of the code has been used by other scientists, including in 
publications he lists. (Id. at PageID.101782.)                            
    VNA also points out that Dr. Specht did not share the MATLAB         
code with peer reviewers when publishing his research. (ECF No. 2913-     

3, PageID.96234.) Dr. Specht explains that there would be no reason to    
submit MATLAB code for peer review during the publication process. He     
asserts that in his field, submitting the code would make little sense,   

because the core aspects of the MATLAB code are “known science and not    
novel to the community as a whole.” (ECF No. 3011-6, PageID.101784.)      

    Based  on  the  record  before  the  Court,  the  peer-reviewed      
publications that accepted Dr. Specht’s research, which relied upon the   
pXRF   device,  did  not  request  the  underlying  MATLAB  code  for     

examination as a condition of publication. That provides support for Dr.  
Specht’s statement that “the contention that the specific MATLAB code     
itself needs to be peer reviewed is completely foreign in the field of XRF 

                              10                                         
research.” (Id.) According to Dr. Specht, experts in this field trust the 

results of this methodology as capable of producing reliable scientific   
results without peer review of the underlying MATLAB code.                
    This suggests that Dr. Specht’s methodology has been subject to      

“the usual rigors of peer review.” Gissantaner, 990 F.3d at 465 (citation 
omitted). The “usual rigors” of scientific practice do not require MATLAB 
code  to  be  submitted  for  review.  That  indicates  that  Dr.  Specht’s 

methodology, which includes at least some aspects of the MATLAB code      
relied upon here, “is taken seriously by other scientists, i.e., that it meets 
at least the minimal criteria of good science.” Id. VNA vastly overstates 

its argument, then, when it claims that the MATLAB code “does not have    
any indicia of scientific reliability.” (ECF No. 2913-3, PageID.96234.)   
    The  peer  review  factor  in  the  Daubert  analysis  overall  favors 

admission of Dr. Specht’s testimony. Dr. Specht’s broader methods have    
been subject to peer review and publication. Scientists rely on pXRF      
devices and publish research that relies upon it. His colleagues have     

reviewed and adopted key elements of his methods, including reviewing     
MATLAB code that is similar to Dr. Specht’s code. (See ECF No. 3011-6,    
PageID.101784 (Dr. Specht stating that “the only parts of the code that   

                              11                                         
are unique are the portions of the code related to calibrating the actual 

pXRF being used.”).) VNA is therefore incorrect that the peer review      
factor  indicates  a  lack  of  indicia  of  scientific  reliability  for  the 
methodology as a whole.                                                   

         ii.  Error Rates                                                
    VNA contends that Dr. Specht’s MATLAB code is so error prone         
that  the  Court  must  exclude  it  as  unreliable.  VNA  argues  that  the 

MATLAB code “contains two fatal problems”: the way that it identifies     
and quantifies lead in a sample and the way it generates “uncertainty     
values.” (ECF No. 2913-3, PageID.96235–96238.) It asserts that these      

flaws lead to “demonstrably false results that confirm that [the MATLAB   
code] is unreliable”: detecting lead in samples known to contain “little or 
no  lead,”  generating  85%  false  positive  rates  when  presented  with 

random noise in a simulation created by VNA’s expert, reporting negative  
lead levels in Flint children, and failing to generate results that correlate 
with  results  generated  by  other  XRF  devices.  (Id.  at  PageID.96238–

96241.)                                                                   



                              12                                         
      a. The MATLAB Code and Lead “Fingerprints”                         

    VNA argues that the MATLAB code functions improperly, because        
the  way  the  code  processes  data  does  not  incorporate  certain     
requirements  that  must  be  satisfied  for  lead  to  be  present.  (Id.  at 

PageID.96235.)  VNA  invokes  the  laws  of  physics,  stating  that  when 
identifying the presence of lead or other atoms these laws dictate that   
    (1) [] peaks [in the spectral data] will always take the shape       
    of a Gaussian (or bell-shaped) curve; (2) the Gaussian curve         
    will always be at least as wide as a minimum width, known            
    as the “Fano limit”; and (3) the Gaussian curve will always be       
    centered  around  particular  energies  (colors)  that  are          
    characteristic of the atoms in the test specimen.                    

(Id. at PageID.96229.) According to VNA’s experts’ explanation of the     
“fingerprint” of lead, the peak Dr. Specht seeks to identify is at 12.618 
keV (the “L-beta (Lβ) peak”) and the Fano limit (the minimum width of     
the curve) is 175 eV. (Id.) If the MATLAB code does not identify lead     
based on the lead fingerprint described above, then it will be unable to  
distinguish  lead  from  background  noise,  according  to  VNA.  (Id.  at 

PageID.96226.) VNA argues that the bone lead levels identified by Dr.     
Specht’s MATLAB code do not fit the lead fingerprint, which means the     


                              13                                         
lead levels Dr. Specht identifies may be the result of noise and not lead. 

(Id. at PageID.96236.)                                                    
    Plaintiffs respond that VNA’s objections amount to nothing more      
than a battle of the experts because Dr. Specht rejects the claim that lead 

must appear in the form of a specific lead fingerprint. (ECF No. 3013,    
PageID.101943.)  Dr.  Specht,  in  a  declaration,  offers  an  alternative 
account of what is necessary for his pXRF device to properly identify and 

measure lead in bones. (ECF No. 3011-6, PageID.101788.) Citing several    
scientific  articles,  he  discusses  his  approach  in  terms  of  “counting 
statistics,” which he explains as follows:                                

    Counting statistics, in the context of XRF detectors, refers to      
    the  statistical  analysis  of  data  obtained  from  XRF            
    measurement   experiments.  It’s  a  subset  of  nuclear             
    instrumentation that deals primarily with the quantification         
    or counting of individual particles or quantum events. In XRF        
    we count the number of events at a certain energy in a certain       
    time. These events occur at a predictable average rate, which        
    is proportional to the intensity. The statistical fluctuations in    
    these  counts  are  described  by  Poisson  distribution,  a         
    probability distribution that represents the number of events        
    in a fixed interval of time or space.                                

(Id. at PageID.101782 n.3.) Dr. Specht argues that lead counts trend in a 
Gaussian  shape,  but  “an  increase  in  counts  in  the  energy  range  
                              14                                         
associated with lead” is what “delineate[s] lead.” (Id. at PageID.101788; 

see also id. at PageID.101797 (“[T]he counts in the lead region for the   
children identified are being compared within and outside of the lead     
region to arrive at the given bone lead measurement and uncertainty       

specific to each child.”).) He explains that various factors can shift the 
center of a Gaussian curve formed by lead counts such that its center may 
not always be 12.618 keV. (Id. at PageID.101788–101789.) He also denies   

lead measurements must always be in the form of a curve wider than 175    
eV. (Id. at PageID.101789–101790.)                                        
    In VNA’s reply, it argues that Dr. Specht’s declaration is in tension 

with the assumption that lead forms a Gaussian curve, which it argues     
is built into his code and is referenced in his research. (ECF No. 3037-1, 
PageID.102709–102710.) VNA puts the issue as follows:                     

    So either lead does not generate a Gaussian curve and Dr.            
    Specht’s  MATLAB   code  is  unreliable  (because  the  code         
    assumes  lead  generates  a  Gaussian  curve),  or  lead  does       
    generate a Gaussian curve and Dr. Specht’s scans of Plaintiffs       
    do not show lead (because the curves fitted by Dr. Specht’s          
    code are far too narrow, and often in the wrong location, to         
    represent lead).                                                     

(Id. at PageID.102710.)                                                   
                              15                                         
    It  is  not  clear  why  Dr.  Specht’s  use  of  Gaussian  curves  in  his 

MATLAB code requires him to accept VNA’s experts’ views about lead        
fingerprints. Dr. Specht does not believe the curves he fits to his data are 
too  narrow  or  in  the  wrong  location  to  identify  lead,  because  his 

methodological  assumptions  differ  from  VNA’s  experts’  assumptions.  
Whether the lead fingerprint described by VNA’s experts must guide Dr.    
Specht’s analysis is in dispute. As a result, Dr. Specht’s discussion of  

these issues does not create a contradiction, nor does it undermine his   
methods. Cf. United States v. Smallwood, No. 5:08–CR–38, 2010 WL          
4168823, at *5–6 (W.D. Ky. Oct 12, 2020) (excluding an expert’s opinion   

and noting the contradiction between an expert’s published studies and    
his opinion). Instead, VNA’s experts have presented what they believe     
are  core  requirements  for  a  proper  analysis  of  these  issues,  and  Dr. 

Specht denies that these requirements apply.                              
    In the “classic battle of the experts,” it is up to the jury to weigh 
what “weight and credibility” to afford each expert’s opinion. Phillips v. 

Cohen, 400 F.3d 388, 399 (6th Cir. 2005) (citation omitted). Further,     
“[t]he test set out in Daubert does not require that the Court look to one 
expert to determine the credibility of another expert’s determination.”   

                              16                                         
Fox v. Mass. Bay Ins. Co., No. 2:13-cv-02567, 2015 WL 11017961, at *3     

(W.D. Tenn. Mar. 12, 2015). On their own, these competing accounts of     
what a reliable approach to lead detection in bone should look like cannot 
be resolved by the Court. Disagreements over method alone do not create   

a basis for exclusion, and VNA has not demonstrated that Dr. Specht’s     
bone lead testing was the result of speculation, a contradiction, or a more 
general lack of a reliable foundation. Instead, they have presented their 

experts’  dispute  with  Dr.  Specht  about  the  importance  of  lead    
fingerprints in properly determining the Bellwether III Plaintiffs’ bone  
lead levels.  See In re Scrap Metal, 527 F.3d at 529–30.                  

      b. The MATLAB Code and Uncertainty Values                          
    VNA   also  argues  that  Dr.  Specht’s  approach  to  determining   
uncertainty  values  for  his  measurements  is  flawed.  Dr.  Specht’s   

methodology generates an uncertainty value when the pXRF is used to       
measure  lead  in  bone.  (ECF  No.  3011-6,  PageID.101788.)  After      
performing bone scans on the Bellwether Plaintiffs, Dr. Specht found that 

lead was present when the amount of lead detected was greater than the    
uncertainty  value.  (See,  e.g.,  ECF  No.  2913-31,  PageID.97441       
(calculating one Plaintiff’s bone lead level as 1.42 ug/g, calculating the 

                              17                                         
measurement uncertainty as 0.49 ug/g, and concluding that they were       

exposed to lead).)                                                        
    Daubert instructs courts to consider “the known or potential rates   
of error” for a methodology. 509 U.S. at 594. If a method has “a high error 

rate,  if  it  has  trouble  avoiding  false  positives,  and  if  there  are  no 
standards or guidelines to avoid or lessen these risks,” then this factor 
weighs against admission. Gissantaner, 990 F.3d at 465 (cleaned up). The  

Sixth Circuit instructs that even when the calculation of an error rate   
has  “troubling”  deficiencies,  including  the  failure  to  conduct  certain 
important tests, error rate “is only one in a list of nonexclusive factors 

that  the  Daubert  Court  observed  would  bear  on  the  admissibility  
question.” United States v. Bonds, 12 F.3d 540, 560 (6th Cir. 1993).      
    VNA argues that Dr. Specht’s MATLAB code calculates rates of         

error in a manner that ignores important considerations and ignores       
possible results. (ECF No. 2913-3, PageID.96238 (“[I]t does not employ    
any statistical method to determine whether the peak it attempts to       

measure was generated by noise or an actual lead signal, and it does not  
account  for  the  limit  of  detection  of  the  device[.]”);  ECF  No.  3037-3, 
PageID.102760 (Dr. Huber stating that the code “does not capture all the  

                              18                                         
uncertainty  associated  with  Dr.  Specht’s  measurements”).)  VNA  also 

argues that the MATLAB code used to measure lead in the Bellwether        
Plaintiffs’ bones does not calculate error in the same manner as Dr.      
Specht does in his publications and, if he had done so, it would have     

shown that no lead was detected in these Plaintiffs. (ECF No. 2913-3,     
PageID.96238; ECF No. 3037-3, PageID.102761.)                             
    Dr. Specht denies this characterization of how the code produces     

uncertainty  values.  Citing  his  publications,  he  asserts  that  the  code 
“inherently  accounts  for  limits  of  detection  and  uses  standard  error 
propagation to determine the uncertainty of the measurement.” (ECF No.    

3011-6,  PageID.101798–101799.)  He  also  claims  that  Dr.  Huber       
mischaracterizes how the MATLAB code generates uncertainty values.        
(Id. at PageID.101792–101793.)                                            

    If VNA’s experts are correct, and Dr. Specht’s MATLAB code cannot    
calculate  a  proper  error  rate,  this  deficiency  would  weigh  against 
admission. But VNA does not establish such a deficiency. The parties’     

disagreement about how the code accounts for uncertainty and error and    
whether the code mirrors the equations in Dr. Specht’s publications are   
not questions for the Court to decide. In re Scrap Metal, 527 F.3d at 529–

                              19                                         
30 (ruling that under Rule 702 and Daubert courts should not decide       

between contested versions of the facts and citing with approval Quiet    
Tech. DC–8, Inc. v. Hurel–Dubois UK Ltd., 326 F.3d 1333, 1343–44 (11th    
Cir. 2003), where testimony was admitted even though “the appellant       

argued that the expert . . . used the wrong equations to run the analysis”). 
The Court’s role is not to assess the credibility of the experts’ factual 
statements about what computer code is doing when it processes data.      

Phillips, 400 F.3d at 399; Fox, 2015 WL 11017961, at *3. The Court will   
not resolve these factual disputes or weigh the credibility of experts with 
competing accounts of how the computer code generates results. VNA        

therefore does not establish any deficiency in error rate calculation or any 
unreliability in Dr. Specht’s methods. See Gissantaner, 990 F.3d at 465.  
    Next, VNA argues that the alleged flaws related to error rate result 

in “demonstrably false results that confirm that [the MATLAB code] is     
unreliable.”  (ECF  No.  2913-3,  PageID.96238–96241.)  The  Court        
considers VNA’s additional arguments regarding error rate below.          

      c.  Measurements of Lead in Phantoms as Evidence of Error          
    Dr. Huber points to the example of “phantoms” to show that Dr.       
Specht’s  methodology  is  error  prone.  Phantoms  are  plaster  of  paris 

                              20                                         
samples that are used for calibrating pXRF devices. Dr. Specht employs    

this  calibration  process  to  account  for  “subtle  differences”  between 
instruments  used   for  lead  measurement.   (ECF   No.  3011-7,         
PageID.101833–101834.) Dr. Specht used phantoms “with known lead          

level[s]” for this purpose. (ECF No. 2913-31, PageID.97441.) According to 
Dr.  Huber’s  analysis,  Dr.  Specht’s  code  generates  clear  errors  when 
applied  to  data  generated  by  such  phantoms.  (ECF  No.  2913-29,    

PageID.97258.) In his deposition, Dr. Specht stated that the phantoms     
he used have 0.48 μg/g of lead. (ECF No. 2913-33, PageID.97542.) Dr.      
Huber found that                                                          

    the code reports detections as high as 12.37 μg of lead per          
    gram of bone mineral in these phantom bone control samples,          
    far higher than the bone lead concentrations reported in the         
    plaintiffs. 10/26/23 Report at ¶¶ 21-24. This illustrates that       
    the code can mistakenly interpret background noise as lead           
    and generate false positive readings exceeding 10 μg/g, even         
    when no lead is present.                                             

(ECF No. 2913-29, PageID.97265.) On its face, a measurement of 12.37      
μg/g appears to be a highly inaccurate result. Some measurements were     
closer to 0.48 μg/g, but it appears that there were several significantly 
inaccurate readings. (See id. at PageID.97258–PageID.97261 (including     
                              21                                         
readings of 2.63 ± 1.03 μg/g, 3.78 ± 2.04 μg/g, 4.42 ± 1.42 μg/g, among   

other readings, some of which were closer to 0.48 μg/g).)                 
    While  the  code  yielded  incorrect  measurements  of  lead         
concentration when applied to the phantoms, Dr. Specht explains that      

“the code is calibrated only for human bone measurements.” (ECF No.       
3011-6, PageID.101799, 101801.) According to Dr. Specht, Dr. Huber has    
not revealed a flaw in the code, because the code was never meant to      

provide accurate measurements of lead in something like a phantom.        
    However, in VNA’s reply, it points out that Dr. Specht’s comments    
in his published work imply that phantoms can be used for calibration,    

because  XRF  spectra  from  bone  and  those  from  phantoms  are  not   
significantly different. (See ECF No. 3037-1, PageID.102711.) At oral     
argument,  Plaintiffs  explained  that  VNA  misconstrues  Dr.  Specht’s  

comments in his published work. (ECF No. 3081, PageID.105981 (“[T]he      
way that the spectra comes out of pXRF is the same. . . across different  
materials [but] is distinct from what the MATLAB code does with that      

spectra[.]”); id. at PageID.105982–105983 (“[H]e’s explaining that there  
are . . . similarities in the way the pXRF reads the spectra, but that    


                              22                                         
doesn’t mean that the MATLAB code calculation will be exactly the same    

for the phantom versus wet bone versus dry bone[.]”).)                    
    Plaintiffs explain that Dr. Specht’s code is not intended to perform 
measurements  of  lead  in  phantoms,  though  the  device  can  still  be 

calibrated  using  such  phantoms.  The  fact  that  the  MATLAB  code  is 
unable to accurately perform a task for which it is not intended does not 
show that it is unreliable or error prone. Nor do these results require the 

Court  to  conclude  that  there  are  any  problems  with  Dr.  Specht’s 
calibration of the device, given that calibration is apparently separate  
from  other  data  processing  the  device  performs.  (ECF  No.  3011-6, 

PageID.101784  (stating  that  the  parts  of  the  code  that  generate  
measurements of lead and uncertainty values are different from the parts  
of the code that address calibration of a specific instrument).)          

      d. Monte Carlo Simulation as Evidence of Error                     
    Dr. Huber also tested the MATLAB code using a so-called Monte        
Carlo simulation and found an 85% false positive rate.3 (ECF No. 2913-    


    3 The Fifth Circuit provides a brief explanation of the Monte Carlo method: 
    Monte Carlo measures the probability of various outcomes, within the 
    bounds of input variables . . . . Instead of simply averaging the input 
    values, Monte Carlo analysis uses randomly-generated data points to  
                              23                                         
3, PageID.96239.) VNA explains that “Dr. Huber fed the [MATLAB] code      

spectra data consisting of random noise with no lead signals present,     
modeled on actual noise from spectra generated by the pXRF device that    
were produced in this litigation.” (Id.) Essentially, Dr. Huber generated 

random noise that could not have indicated the presence of lead and       
tested how Dr. Specht’s MATLAB code would respond to it. That random      
noise is supposed to be realistic (i.e. it is the type of fluctuation that the 

pXRF might encounter in the real world), because it was modeled on “the   
random fluctuations observed in the 67 spectra Dr. Specht produced in     
the case.” (ECF No. 2913-29, PageID.97266.) Dr. Huber obtained a wide     

range of results in the test, but 85% were false positives, because the   
measured  concentration  of  lead  did  not  exceed  its  measurement     
uncertainty, meaning Dr. Specht’s method would have found lead to be      

present despite the spectra being random noise. (Id.) VNA argues that     


    increase accuracy, and then looks to the results that those data points 
    generate.  The  methodology  is  particularly  useful  when  reaching  an 
    exact numerical result is impossible or infeasible and the data provide a 
    known range—a minimum and a maximum, for example—but leave the       
    exact answer uncertain.                                              

Lyondell Chem. Co. v. Occidental Chem. Corp., 608 F.3d 284, 293 (5th Cir. 2010). 
                              24                                         
finding this level of lead when none was present shows that Dr. Specht’s  

results cannot be distinguished from those based on random noise. (ECF    
No. 2913-3, PageID.96240.)                                                
    Plaintiffs object to the way this simulation was carried out. Dr.    

Specht argues that Dr. Huber did not actually use a Monte Carlo method,   
because he did not generate the random data “within the bounds of real-   
world  parameters.”  (ECF  No.  3011-6,  PageID.101799,  101802.)  Also,  

because actual data related to lead is not random, Dr. Specht asserts that 
Dr. Huber’s method of “using random numbers for data is not going to      
adequately  identify  the  potential  variation  in  methodology.”  (Id.  at 

PageID.101800.) It will miss out on “complex interactions” that would     
occur in real life. (Id. at PageID.101802.) Dr. Specht also insists that he 
and  his  co-authors  have  verified  this  method  via  experiment.  (Id.  at 

PageID.101800.) VNA responds that Dr. Specht’s code is supposed to        
distinguish between noise and lead, and Dr. Huber’s simulation shows      
that the code fails to do that. (ECF No. 3037-1, PageID.102711–102712.)   

Dr. Huber expresses disagreement about whether he performed a valid       
Monte Carlo simulation, but he does not elaborate beyond noting his       
disagreement. (ECF No. 3037-3, PageID.102757 n.1).                        

                              25                                         
    If Dr. Huber’s simulation offered clear evidence that Dr. Specht’s   

code was unable to distinguish noise from lead, that would speak to the   
error rate  factor  in the  Daubert  analysis,  but  the  significance of the 
simulation is subject to disagreement. The dispute here appears to be     

whether Dr. Huber’s test relies on data (i.e. the simulated noise) that is 
adequately  like  real  background  noise  to  test  the  reliability  of  Dr. 
Specht’s code. Experts retained by the parties offer differing opinions on 

this  question.  Dr.  Huber’s  response  to  Dr.  Specht  is  a  conclusory 
statement of his disagreement. (Id.) This record does not allow the Court 
to resolve this issue without impermissibly weighing the credibility of   

two competing experts’ testimony. See Jahn v. Equine Servs., PSC, 233     
F.3d 382, 391 (6th Cir. 2000). As a result, the Court cannot determine    
whether Dr. Huber’s results address the way Dr. Specht’s code functions   

in real-world conditions, as opposed to the simulated conditions created  
by Dr. Huber. This evidence therefore does not weigh in favor or against  
the admissibility of Dr. Specht’s opinions.                               

      e.  Negative Lead Levels as Evidence of Error                      
    VNA also argues that “the MATLAB code reported negative lead         
levels for more than 200 of Dr. Specht’s bone scans of Flint children.”   

                              26                                         
(ECF No. 2913-3, PageID.96240 (emphasis in original).) Because having     

a negative measurement of lead in a person’s bones is not possible, VNA   
asserts that these results are further evidence of the code’s inability “to 
distinguish between noise and a true lead signal.” (Id.) Dr. Specht does  

not disagree that the code reported negative lead levels. He states that  
such a result is “expected” and explains that if there were tests where   
“bone lead [was] nearly zero” and a high level of uncertainty, that would 

yield a negative value. (ECF No. 3011-6, PageID.101803.) Such a result    
does not demonstrate lack of reliability. It is how the code expresses    
results.  Dr.  Specht  indicates  that  his  published  work  includes  such 

negative results. (Id.)                                                   
    VNA provides no substantive response to Dr. Specht’s explanation.    
Further,  insofar  as  this  data  was  included  in  published  work,  that 

suggests it is consistent with scientific practice and not something the  
scientific community would view as evidence of a lack of reliability. VNA’s 
argument that negative lead levels indicate a lack of reliability therefore 

fails.                                                                    



                              27                                         
      f.  Lack of Correlation Between pXRF and KXRF as Evidence of       
         Error                                                           
    VNA also contends that the pXRF is unreliable because of its failure 

to  correlate  with  more  established  KXRF  technology.  VNA  refers  to 
KXRF as the “gold standard” in this context—an assessment Dr. Specht      
shares. (ECF No. 2913-3, PageID.96226; ECF No. 2913-29, PageID.97268      

(citing Dr. Specht referring to the KXRF as the “gold standard”).) VNA    
focuses its critique on measurements at lower—but still substantial—      
lead  levels.  Based  on  the  data  included  in  the  papers,  Dr.  Huber 

estimates that when lead concentrations are measured at “30 μg/g or less  
by the pXRF device, the [correlation with the KXRF] was essentially       
zero.” (ECF No. 2913-29, PageID.97269.) Rather than its measurements      

correlating with the KXRF device, the pXRF device tends to overreport     
lead levels relative to the KXRF device, according to VNA. (ECF No.       
2913-3, PageID.96241.)                                                    

    Plaintiffs  respond  that  although  one  study  found  less  of  a  
correlation between pXRF and KRXF than expected, another one found        
significant  associations  between the  measurements  taken  by  the  two 

devices despite “all but one individual [having] bone lead results less   

                              28                                         
than  30  ug/g.”  (ECF  No.  3013,  PageID.101948.)  Dr.  Huber  found,   

however, that the correlation identified in the study was the result of one 
bone lead level that was at a much higher level than the others and that  
measurements below 15 μg/g did not correlate at all. (ECF No. 2913-36,    

PageID.97732.) His analysis leads him to conclude that the “pXRF is       
biased high by 2.5 ppm.” (Id.)                                            
    Even if there is a lack of correlation between pXRF and KXRF as      

Dr. Huber  asserts, this  failure  to  correlate to  a  different established 
methodology goes to the weight of the evidence and not admissibility. See 
Best  v.  Lowe’s  Home  Ctrs.,  563  F3d  171,  181  (6th  Cir.  2009)    

(“Admissibility under Rule 702 does not require perfect methodology.      
Rather, the expert must employ[ ] in the courtroom the same level of      
intellectual  rigor  that  characterizes  the  practice  of  an  expert  in  the 

relevant field.” (cleaned up)). Scientists, including Dr. Specht, use pXRF 
for  lead  detection  in  published  work,  which  indicates  Dr.  Specht’s 
methods in this litigation have a similar level of rigor to the practice of 

experts in this field. Any lack of correlation to KXRF challenges the     
accuracy of this method, but it does not establish the device’s lack of   


                              29                                         
reliability.  See  In  re  Scrap  Metal,  527  F.3d  at  529  (distinguishing 

accuracy from reliability).                                               
      g. The Evidence Related to Error Rates                             
    VNA  presents  two  general  arguments  about  the  flaws  in  Dr.   

Specht’s MATLAB code. On their own, these objections—about how the        
MATLAB    code  identifies  lead  and  calculates  uncertainty  values—   
amount  to  a  battle  of  the  experts  that  does  not  provide  a  basis  for 

exclusion.  As  further  support  for  their  position,  VNA  offers  four 
arguments, grounded in its experts’ analysis of evidence, to establish the 
MATLAB code is flawed. As set forth above, while these arguments point    

to possible flaws in Dr. Specht’s approach, they do not justify exclusion of 
his opinions. Nor do they establish a high error rate or inability to avoid 
false positives under the error rate factor of the Daubert analysis. The  

error rate factor does not favor exclusion.                               
         iii.  Testability                                               
    VNA argues that Dr. Specht has not tested the code to confirm it     

can identify low levels of lead in children’s bones. In support of this   
argument, VNA points to studies considering the correlation between       
pXRF and KXRF results, (ECF No. 2913-3, PageID.96241), and studies        

                              30                                         
that indicate potential limitations in the context of testing children’s  

bones. (Id. at PageID.96241–96242.) It adds that no further studies have  
been done to verify Dr. Specht’s methodology with respect to children and 
that Dr. Specht has not published research based on his work in Flint.    

(Id.)                                                                     
    The Court has already addressed related arguments from VNA.          
Although the Court acknowledged that the available research was not       

definitive on its own, it noted improvements to Dr. Specht’s process, as  
well as research showing that longer measurement times and “altered       
calibration settings [] improve accuracy.” Specht I, 2021 WL 5356295, at  

*4. VNA argues that these studies do not “validate the MATLAB code for    
measuring low levels of bone lead like those at issue in this case.” (ECF 
No. 2913-3, PageID.96242.)                                                

    Plaintiffs point out that VNA’s entire argument here applies an      
improper standard. As the Court has explained, the testability factor in  
the Daubert analysis asks                                                 

    whether a witness’ technique or technology could be falsified        
    or  refuted  through  the  scientific  method.  United  States  v.   
    Gissantaner, 990 F.3d 457, 464 (6th Cir. 2021) (citing United        
    States  v.  Bonds,  12  F.3d  540,  559  (6th  Cir.  1993)).  “An    
                              31                                         
    untestable scientific theory is all theory and no science.” See      
    Gissantaner, 990 F.3d at 463.                                        

Specht I, 2021 WL 5356295, at *3. VNA’s arguments are about whether       
Dr. Specht’s methodology has been tested—not whether it is testable.      
Arguments “about the adequacy of the [theory’s] testing . . . provide grist 

for adversarial examination, not grounds for exclusion.” Gissantaner, 990 
F.3d at 464 (cleaned up).  Dr. Specht’s methodology is clearly testable and 
Dr. Huber purports to have tested it.4 Accordingly, just like the last time 


    4 Putting to the side that VNA relies on the wrong standard, it also argues that 
Dr. Specht’s claim that the pXRF device successfully detected lead in Plaintiffs is an 
untested hypothesis and is therefore unsuited for admission due to being speculative. 
(ECF No. 3037-1, PageID.102714.) VNA cites Tamraz v. Lincoln Elec. Co., which 
involves an expert who admitted to speculating about brain damage that he had been 
unable to detect in his examination of the plaintiff. 620 F.3d 665, 675–76 (6th Cir. 
2010). Here, Dr. Specht references repeated experiments being used to verify his 
methodology and grounds core elements of his methodology in established research, 
among  other  things.  (ECF  No.  3011-6,  PageID.101782–101783,  101800.)  This 
methodology is unlike the speculation at issue in Tamraz.                 
    Further, many of the arguments offered by VNA relate to application of the 
methodology to low blood levels. (ECF No. 3037-1, PageID.102714.) Arguments about 
application are rarely a basis for exclusion. See Specht I, 2021 WL 5356295, at *6.  As 
the Court set forth:                                                      
    The  pXRF  technology  itself  is  widely  accepted  in  the  scientific 
    community. Recent publications likewise validate the use of pXRF to  
    measure bone lead in human subjects specifically. Defendants may cast 
    doubt on the application of this technology to the children in this case—
    but the trial is the appropriate place for such arguments, and a jury the 
    appropriate audience.                                                
                              32                                         
the  Court  considered  the  admissibility  of  Dr.  Specht’s  opinions,  “the 

testability factor weighs strongly in favor of admission.” Specht I, 2021 
WL 5356295, at *3.                                                        
         iv.  General Acceptance                                         

    VNA argues that Dr. Specht’s methodology has not been generally      
accepted,  which  weighs  against  admission.  (ECF  No.  2913-3,         
PageID.96245.)  General  acceptance  is  one  of  the  factors  outlined  in 

Daubert:                                                                  
    “general acceptance” can [] have a bearing on the inquiry. A         
    “reliability  assessment  does  not  require,  although  it  does    
    permit,  explicit  identification  of  a  relevant  scientific       
    community  and  an  express  determination  of  a  particular        
    degree of acceptance within that community.” United States           
    v. Downing, 753 F.2d, at 1238. See also 3 Weinstein & Berger         
    ¶ 702[03], pp. 702–41 to 702–42. Widespread acceptance can           
    be  an  important  factor  in  ruling  particular  evidence          
    admissible, and “a known technique which has been able to            
    attract  only  minimal  support  within  the  community,”            
    Downing, 753 F.2d, at 1238, may properly be viewed with              
    skepticism.                                                          



Id. Insofar as VNA’s focus is on application that is a further reason its arguments 
fail.                                                                     
                              33                                         
509 U.S. at 594. The  Sixth  Circuit  has  explained  that  “[o]nly  when  a 

theory or procedure does not have the acceptance of most of the pertinent 
scientific  community,  and  in  fact  a  substantial  part  of  the  scientific 
community disfavors the principle or procedure, will it not be generally  

accepted.” Bonds, 12 F.3d at 562.                                         
    To show that Dr. Specht’s methodology is not generally accepted,     
VNA makes several arguments. It suggests that pXRF testing and the        

MATLAB code discussed in this motion have not been independently          
evaluated. (ECF No. 2913-3, PageID.96244.) VNA points out that Dr.        
Specht references peer-reviewed publications that he co-authored rather   

than  those  authored  by  other  people  and  that  others  (including   
government agencies) have not adopted the pXRF. (Id. at PageID.96244–     
96245.) It also notes that Dr. Specht has not sought FDA approval, which  

would require review of the MATLAB code for safety and efficacy. (Id. at  
PageID.96245.)                                                            
    Plaintiffs point out that the Court has considered many of these     

arguments already. The Court explained that                               
    while Dr. Specht is the pre-eminent figure in the development        
    of pXRF in in vivo studies, he is hardly the only researcher in      
    this field. Indeed, in each of the studies to which both parties     
                              34                                         
    refer, Dr. Specht has several collaborating co-authors. E.g.,        
    (Specht (2014), Specht (2019a)). And the large-scale Zhang           
    study  of  subjects  in  Indiana  and  Chicago  was  completed       
    largely without Dr. Specht’s involvement, by a separate group        
    of researchers. Zhang (2021).                                        

    In addition, the pXRF technology at issue in this case is not        
    as novel as VNA suggests. Portable XRF devices have a long           
    history of use in non-medical contexts. . . . Dr. Specht’s own       
    methods  have  been  subjected  to  almost  a  decade  of  peer      
    review, and they have not come under attack as unscientific          
    or otherwise lacking.                                                

Specht I, 2021 WL 5356295, at *5. In Dr. Specht’s deposition, he also     
explains that his research—undertaken with co-researchers—continues       
to use pXRF technology very similar to what he used to test Plaintiffs.   
(See ECF No. 3011-7.)                                                     
    Dr. Specht’s status as co-author on peer-reviewed publications that  
rely upon pXRF is evidence of general acceptance. The fact that other     
scientific researchers have worked with Dr. Specht on past and current    
research  using  his  methods  weighs  in  favor  of  finding  that  they  are 
generally accepted. Even if he worked on this research entirely on his    
own, the general acceptance factor is not reducible to the number of      

people who use a methodology. See United States v. Jones, 965 F.3d 149,   

                              35                                         
156, 160, 162 (2d Cir. 2020) (finding that although a laboratory was the  

only one that used a methodology, it was still generally accepted based   
on peer review and other approvals from the scientific community).        
    VNA has not provided evidence that this methodology is disfavored,   

Bonds, 12 F.3d at 562, nor does it point to evidence that the scientific  
community  views  Dr.  Specht’s  work  as  “unscientific  or  otherwise   
lacking.” Specht I, 2021 WL 5356295, at *5. Rather, there is evidence this 

methodology  has  been  evaluated  and  adopted  by  members  of  the     
scientific  community.  The  general  acceptance  factor  therefore  favors 
admission.  To  the  extent  VNA  intends  to  attack  this  methodology’s 

applicability to children or to certain bone lead levels, those arguments 
relate to applicability and are appropriate for presentation to a jury. Id. 
at *6. They do not justify exclusion of this evidence. Accordingly, VNA’s 

arguments based on general acceptance fail.                               
    Overall,  the  Daubert  analysis  favors  admission  of  Dr.  Specht’s 
opinions. While some of VNA’s arguments regarding the error rate may      

expose flaws in Dr. Specht’s methodology, even that factor does not favor 
exclusion. These factors are not “a definitive checklist or test” but are 
instead intended to guide courts in “strik[ing] a balance between a liberal 

                              36                                         
admissibility standard for relevant evidence on the one hand and the      

need to exclude misleading ‘junk science’ on the other.” Best, 563 F.3d at 
176–77 (cleaned up).                                                      
    Dr. Specht’s opinions and methodology are not junk science. He is    

qualified to offer his opinions, and he draws on his peer-reviewed and    
published research to do so. VNA’s experts’ competing scientific theories, 
its  experts’  criticisms  and  objections,  and  its  views  on  the  proper 

application of Dr. Specht’s methodology may be raised at trial, but they  
do not provide a basis to exclude this testimony. Accordingly, VNA’s      
arguments for excluding Dr. Specht’s testimony in its entirety are denied. 

      B.  The   Half-Life  of  Lead  in  Children  and  Related          
          Opinions                                                       
    VNA also objects to Dr. Specht’s opinion that bone lead levels in    
children have a five-year half-life. (ECF No. 2913-3, PageID.96246.) It   
further objects to several opinions Dr. Specht offers on the basis of this 

assumption, some of which are included in the following portion of Dr.    
Specht’s report:                                                          
    The lead exposure results from Flint were drastically higher         
    than comparable community studies. The bone lead of the              
    children in Flint had an average measure of 4.1 ± 6.6 ug/g.          
    These results from the Flint children were 6.5 times higher          
                              37                                         
    than Ontario children from the McNeil study (McNeill, Fisher         
    et al. 2017). Using a conservative estimate of 5 years for the       
    bone  lead  half-life  in  children,  we  calculate  the  bone  lead 
    values to be 8.2 ± 13.1 ug/g at the start of the Flint water         
    crisis. With these distributions, the population overlap with        
    Chinese children from Specht et al., which had blood lead            
    values of >25 ug/dL, would be greater than 66% (Specht, Lin          
    et al. 2016). This means that 66% of the children from Flint         
    had  bone  lead  and  lead  exposure  profiles  most  similar  to    
    severely  poisoned  children  that  were  prescribed  chelation      
    therapy (Specht, Lin et al. 2016).                                   

(ECF No. 2913-31, PageID.97440.)                                          
    VNA  makes  three  arguments  opposing  the  admission  of  these    
opinions. First, it argues that Dr. Specht does not cite any scientific   
literature in support of his opinion about five-year half-life of bone lead 
in children nor does he otherwise disclose the basis of this estimate. (ECF 
No. 2913-3, PageID.96246–96247.) Second, VNA argues that that his         
estimates of bone lead values of Flint children in 2014 are based on      
unfounded assumptions about when their exposure to lead occurred. (Id.    
at  PageID.96247)  Third,  VNA  contends  that  Dr.  Specht  makes  an    

illegitimate  comparison  to  “severely  poisoned  children  in  his  China 
study.”  (Id.)  In  addition,  VNA  argues  that  these  opinions  should  be 
excluded under Rule 403 as unfairly prejudicial.                          

                              38                                         
    Dr. Specht provides citations for his estimate of the half-life of lead 

in children. Dr. Specht, in his declaration, states that he calculated a five-
year  half-life  “based  on  known  bone  turnover  markers  identified  in 
previous studies.” (ECF No. 3011-6, PageID.101807.) In his deposition,    

Dr. Specht explains that “there is not literature specific to lead in bones, 
but there is literature specific to the bone turnover rates.” (ECF No. 2913-
32, PageID.97513.) He cites a source in his declaration that gives bone   

remodeling rates for subjects at different ages. Basic Anatomical and     
Physiological  Data  for  Use  in  Radiological  Protection:  The  Skeleton, 
ANNALS ICRP, 1995, at 35. https://journals.sagepub.com/doi/pdf/10.1177    

/ANIB_25_2. Dr. Specht provided his calculations related to this opinion  
to  VNA  after  his  deposition.  (ECF  No.  3011-6,  PageID.101807  n.14 
(noting he provided the calculation to counsel).)                         

    Experts are permitted to make reasonable scientific inferences from  
data. See Jahn, 233 F.3d at 390. However, under Rule 702, the burden is   
on Plaintiffs to show by a preponderance of the evidence that testimony   

is based on sufficient facts or data. Fed. R. Evid. 702. Further, there must 
not be “too great an analytical gap between the data and the opinion      
proffered.” Gen. Elec. Co. v. Joiner, 522 U.S. 136, 146 (1997). Plaintiffs 

                              39                                         
did not provide the basis for Dr. Specht’s inference from bone remodeling 

rates at different ages to his estimate of the half-life of bone lead in  
children.  (See ECF  No.  3081,  PageID.106006.)  It  is unclear how and  
whether the source Dr. Specht cites, which relates to bone remodeling     

rates, allows him to estimate the half-life of lead in bones. Plaintiffs also 
do not provide support for Dr. Specht’s claim that his estimate for bone  
lead  half-life  is  “conservative.”  (ECF  No.  2913-31,  PageID.97440.) 

Further, it is unclear how he accounts for the differing ages of Flint    
children in calculating a five-year half-life. The Court therefore cannot 
conclude that Dr. Specht’s estimate is more likely than not based on      

sufficient facts and data. Dr. Specht may not offer testimony about his   
five-year estimate for bone lead half-life.5                              

    5 Although Dr. Specht’s testimony about his estimate of bone lead half-life is 
inadmissible, that does not prevent him from testifying about the significance of 
Plaintiffs’ bone lead levels based on other evidence in the record. For example, the 
Court’s ruling does not preclude Dr. Specht from providing the following sort of 
opinion, which is stated in his report:                                   
    since bone turnover is faster at younger ages, [] the initial lead exposure 
    from the water crisis is higher than what we are seeing here. Thus,  
    [Plaintiff] has a measurable exposure to lead that had accumulated in 
    [Plaintiff]’s bones, and the exposure was at a level that the natural bone 
    turnover rate did not dissipate the lead prior to our XRF measurement. 

(ECF No. 2913-31, PageID.97441.)                                          
                              40                                         
    Because Dr. Specht’s extrapolations of average bone lead levels for  

children in Flint and his comparison to his study of children in China are 
based on his estimate of a five-year bone-lead half-life, those opinions  
must be excluded, as well.                                                

    Exclusion of his comparison of children in Flint with children in his 
study  in  China  is  also  necessary  to  prevent  unfair  prejudice  and 
confusion. Fed. R. Evid. 403 (“The court may exclude relevant evidence if 

its probative value is substantially outweighed by a danger of one or more 
of the following: unfair prejudice, confusing the issues, misleading the  
jury, undue delay, wasting time, or needlessly presenting cumulative      

evidence.”) The probative value of this comparison is weak because Dr.    
Specht  states  that  this  comparison  “only  refer[s]  to  the  potential 
cumulative, chronic exposure distribution overlap in the Flint children   

versus the children that were lead poisoned in China.” (ECF No. 3011-6,   
PageID.101808  (emphasis  added).)  He  offers  an  opinion  about  a     
potentially valid comparison, which suggests a lessened likelihood that   

this testimony will  assist the  jury. See Fed. R. Evid.  702(a). In  part 
because the probative value of this comparison is weak, it is substantially 
outweighed by the danger of unfair prejudice and confusion. Specifically, 

                              41                                         
there  are  serious  risks  that  the  comparison  to  the  study  of  Chinese 

children could lead jurors to conclude that Plaintiffs required chelation 
treatment to remove lead from their bodies like the children in China     
that Dr. Specht compares them to. Old Chief v. United States, 519 U.S.    

172,  180  (1997)  (“Unfair  prejudice .  . . means  an  undue tendency  to 
suggest decision on an improper basis. . . .”). Yet there is no evidence the 
Bellwether III  Plaintiffs required or  other  children in  Flint obtained 

chelation for lead poisoning. These problems compound the issues with     
Dr. Specht’s estimate of bone-lead half-life set forth above. As a result, 
these opinions must be excluded.                                          

    Accordingly, as set forth above, VNA’s motion is granted in part     
with respect to Dr. Specht’s opinions related to his estimate of bone lead 
half-life.                                                                

    IV.  Conclusion                                                      
    For the reasons set forth above, the Motion is GRANTED IN PART       
and DENIED IN PART.                                                       

    IT IS SO ORDERED.                                                    
Dated: September 9, 2024           s/Judith E. Levy                       
Ann Arbor, Michigan                JUDITH E. LEVY                         
                                  United States District Judge           
                              42                                         
                 CERTIFICATE OF SERVICE                                  

    The undersigned certifies that the foregoing document was served     
upon counsel of record and any unrepresented parties via the Court’s      
ECF System to their respective email or first-class U.S. mail addresses   
disclosed on the Notice of Electronic Filing on September 9, 2024.        

                                  s/William Barkholz                     
                                  WILLIAM BARKHOLZ                       
                                  Case Manager                           















                              43                                         

Case Information

Court
E.D. Mich.
Decision Date
September 9, 2024
Status
Precedential