The National Exposure Registry: history and lessons learned

Area of Science:

• Environmental Health
• Toxicology
• Epidemiology

Background:

• The National Exposure Registry (NER) was established to correlate environmental chemical exposures with registrant health conditions.
• It focused on specific chemicals including dioxin, trichloroethylene (TCE), benzene, and trichloroethane (TCA).

Observation:

• The NER's design had significant deficiencies, most critically an inadequate ability to assess exposure levels.
• Other unresolved issues included unverified self-reporting of data, lack of appropriate control groups, and limited use of biomarkers.

Findings:

• The primary limitation of the NER was its failure to adequately measure chemical exposure, termed its 'Achilles heel'.
• Observed excess health effects compared to national norms may stem from methodological variations and reliance on unverified self-reported data.

Implications:

• Establishing a robust chemical exposure registry presents greater challenges than maintaining an outcome-based registry.
• The NER's methodological weaknesses highlight the complexities in accurately linking environmental exposures to long-term health outcomes.