Page 222 - Veterinary Toxicology, Basic and Clinical Principles, 3rd Edition

Toxicology and the Law Chapter | 11 189

VetBooks.ir were excluded, and the exclusion affirmed because the lit- from exposure to a toxic dose of the chemical
in question? Is reliable testimony of the clini-
erature did not support a finding of general causation at
cal signs and lesions available?
the relevant exposure (Amorgianos, 2002). Testimony of
a toxicologist was properly excluded because he per- 2. Rule-out:
formed no dose assessment and showed no statistically a. Can the expert provide a differential diag-
significant link between the chemical and the type of can- nosis list?
cer present (Burleson, 2004). b. Can the expert provide reliable testimony
Reliance on peer reviewed literature is also impor- that the diseases other than the purported
tant. A toxicologist’s testimony was excluded, but the one were ruled out? Can the expert explain
exclusion was reversed, because the toxicologist’s how and why these other diseases were
testimony was supported by peer-reviewed literature ruled out? Were scientifically valid meth-
(Bocanegra, 2003). ods used to rule out these diseases?
When considering exposure: 45

SOME QUESTIONS TO CONSIDER WHEN 1. How can we be sure that the samples taken are actu-
ally representative of the media sampled?
USING LABORATORY RESULTS
2. Standard methods are available to design sampling plans
1. Was the legal aspect of the case known at the time the that have specified probabilities of being representative,
samples were submitted? If not, is the sample tracking but they can never provide complete assurance.
or chain of custody sufficiently well documented to Generally, when contamination is likely to be highly
establish each relevant step of the analysis? Can the rel- homogeneous, there is a greater chance of achieving a
evance of the documents be authenticated? Does chain- reasonably representative sample than is the case when it
of-custody or sample tracking documentation exist? is highly heterogeneous. In the latter circumstance,
2. What type of legal venue is the work to be used in ? obtaining a representative sample, even when very large
Administrative enforcement, civil litigation, criminal numbers of samples are taken, may be unachievable.
litigation? What standard of persuasion is appropriate 3. How can we be sure that the analytical work was done
for this venue? properly?
3. Can the relevance of the analytical results be authenti- 4. What are the pathways from the source to the exposed
cated? What documentation exists that the samples were individuals? How has it been established that those
collected from the appropriate animal? What documen- pathways exist (past? present? future?).
tation exists to demonstrate proper sample identification 5. What is the concentration of the chemical in the media
throughout the laboratory testing process? What docu- with which the exposed population comes into contact
mentation exists to demonstrate that the process used (past? present? future?). What is the basis for this
produces an accurate result—what validation processes answer: direct measurement? modeling?
are in place? Is the interpretation of the test results accu- 6. If the concentration is based on direct measurement,
rate for the type of analytical test performed? what procedures were followed in obtaining that mea-
4. Is the testimony to be as a lay—or fact—witness? surement? Was media sampling sufficient to ensure
5. Is the testimony to be as an expert witness? that it was representative? If not, why is representative-
A. Is the expert a toxicologist? ness not important? Were validated analytical methods
B. Does the scientific literature support an argument used by an accredited laboratory? If not, how can one
of general causation? be assured that the analytical results are reliable?
C. Was a differential diagnosis performed by the 46
When considering a specific causal association:
laboratory?
1. Rule-in:
a. Can the expert provide reliable testimony
that the sample received by the laboratory
is representative of the diseased animals? 45. From Reference Guide on Exposure Science--Joseph V. Rodricks.
b. Can the expert provide reliable testimony National Research Council. 2011. Reference Manual on Scientific
Evidence: Third Edition. Washington, DC: The National Academies
that the animals were in fact exposed to a
Press. doi: 10.17226/13163. See also How should the Courts Assess
toxic dose of the chemical in question ? To
exposure in The Admissibility of expert Testimony Margaret A.
what degree of certainty does the analytical
Berger.
methodology demonstrate exposure of the 46. From Reference Guide on Toxicology--Bernard D. Goldstein and
animal to the chemical in question? Mary Sue Henifin.National Research Council. 2011. Reference Manual
c. Can the expert provide reliable testimony that on Scientific Evidence: Third Edition. Washington, DC: The National
the animals experienced the disease expected Academies Press. doi: 10.17226/13163.