The nervous system is a target organ for various types of compounds. Toxic effects on the brain or peripheral nervous system may have far-reaching consequences. Some neurotoxic effects are reversible while others, such as developmental neurotoxicology effects of lead, are longer lasting. Neurotoxicologists and risk assessors at Exponent are experienced at:
- Analyses of neurotoxicology and neuropharmacology data from the literature and guideline toxicology studies
- Design and monitoring of in vitro and in vivo studies to fill gaps in data
- Quantitative and qualitative risk assessment based on neurotoxicology data
- Development of comments for regulatory bodies
Exponent's scientists provide an objective evaluation of the weight of scientific evidence regarding the possible existence of a link between exposure to a specific compound and a risk of health effects. Exponent’s experts are trained in evaluation of molecular, physiological, behavioral, and epidemiological data, and we provide critical summaries of the strengths and weaknesses of evidence for association or causality. An example of a large-scale literature evaluation is “Evaluation of Epidemiological and Animal Data Associating Pesticides with Parkinson’s Disease,” for which Exponent toxicologists and epidemiologists surveyed the available studies and produced a definitive review.
This figure shows neuronal pathways that degenerate in Parkinson's Disease. Signals that control body movements travel along neurons that project from the substantia nigra to the caudate nucleus and putamen (collectively called the striatum). These "nigro-striatal" neurons release dopamine at their targets in the striatum. In Parkinson's patients, dopamine neurons in the nigro-striatal pathway degenerate for unknown reasons.
Our scientists also are knowledgeable in regulatory requirements for testing and provide advice on design, conduct, and interpretation of required studies. Exponent has built a strong team of scientists who are familiar with studies that evaluate neurotoxic responses in a variety of contexts. With backgrounds in industry and government, Exponent scientists design and evaluate EPA-, FDA-, and EU-approved neurotoxicology and standard toxicology studies to assess effects on the nervous system. The neurotoxicology experts at Exponent have worked with government and industry entities to design studies that address targeted research issues. For example, Exponent scientists currently hold a grant from the British government to determine whether a combination of the pesticides paraquat and maneb are causal factors for Parkinson’s Disease–pattern neurodegeneration.
Further, developmental neurotoxicology (DNT) (i.e., the study of effects relevant to the nervous system during gestation and the early postnatal period) has become increasingly important with the recognition that exposure to a toxicant during development may have consequences into adulthood. Exponent scientists have participated in developing EPA and OECD guidelines for DNT studies and provided expert consultation for industry to design and interpret DNT studies required by U.S. and European regulatory agencies.
Exponent scientists also help in designing in vitro studies to gain critical information regarding mechanisms of action of neurotoxicants. Our experimental experience includes brain slices and neuronal/glial cultures to evaluate the effects of chemical mixtures, solvents, metals, and complex organic molecules. A strong background in basic research allows Exponent scientists to evaluate published studies for appropriate methodology and interpretation of results.