Research on chronic, low-level exposure to formaldehyde: implications for neuropsychological assessment.

Findings from empirical research serve as the foundation for neuropsychological assessment of individuals suspected of exposure to formaldehyde. Insofar as conclusions regarding causal relationships between exposure and neuropsychological deficits are based on research methodologies that are reliable, findings can be informative. Unfortunately, existing research is not rooted in sound methodology and findings may mislead rather than enlighten clinicians. Two prominent shortcomings in formaldehyde research are discussed: selection bias in recruitment of research participants and unreliability of participant recall for obtaining data on important background variables and exposure levels. Selected examples illustrate the influence of these shortcomings on research showing a causal relationship between long-term, low-level exposure to formaldehyde and chronic neurobehavioral deficiencies. The implications of these weaknesses for assessment of individual patients are discussed.