Selective approaches to basic neurobehavioral testing of children in environmental health studies.

To identify neurotoxic effects in children living near hazardous waste sites, the Agency for Toxic Substances and Disease Registry (ATSDR) has designed a basic Pediatric Environmental Neurobehavioral Test Battery (PENTB) for children 1 through 16 years of age. It emphasizes tests appropriate to the stages of a child's development. These stages were fundamental factors in selecting tests for the PENTB, which includes both informant- and performance-based assessment procedures. Assessment of children under 4 years of age is restricted to four informant-based instruments, to evaluate as many functions as possible while minimizing testing time and the professional expertise needed in the test setting. The assessment of children 4 through 16 years of age includes 10 performance-based tests to evaluate key functions within the cognitive, motor, and sensory domains analogous to functions affected by neurotoxic chemicals in adults. In all age groups, it is crucial to also assess family, cultural, economic, and other potentially confounding variables.

Volatile organic compound testing of a population living near a hazardous waste site.

Accurate measures of individual exposure are critical in reducing misclassification and establishing scientifically valid associations between health outcomes and exposures to environmental contaminants. As part of a community health study, the Agency for Toxic Substances and Disease Registry conducted exposure testing for volatile organic compounds (VOCs) in the blood of people residing near an industrial complex. The purposes of the study were to assess recent exposures to VOCs in this community and to assess the utility of conducting blood VOC testing on populations near hazardous waste sites. One hundred blood specimens from the target area and 106 blood specimens from the control area were collected for analysis. The blood VOC levels in the target-area participants were compared to those in the control area and to a national reference population. Of the 31 separate VOCs for which testing was done, only acetone was statistically significantly (p < 0.05) higher in target-area participants (1,636 parts per billion [ppb]) than in control-area participants (1,353 ppb). 1,1,1-Trichloroethane was found at higher geometric mean levels in the control group (0.169 ppb) than in the target group (0.115 ppb) (p = 0.01). Median blood levels of 2-butanone and 1,4-dichlorobenzene were slightly higher in both target- and control-area groups than in the national reference population, but neither area was statistically significantly higher than the national reference population for any contaminant measured. Overall, there appeared to be no association between residing in the target area and elevated blood VOC levels. Based on the results of this study, blood VOC testing should be limited to populations living near sites where environmental testing has shown recent, elevated VOC exposure, or where unusual circumstances of illness may be attributed to VOC exposure.

Adoption of an adult environmental neurobehavioral test battery.

Nationally recognized experts participated in a 3-day workshop to discuss the complex issues associated with neurobehavioral testing in environmental health settings, and to propose basic and focused test batteries for use in evaluating populations living near hazardous chemical sites. The Adult Environmental Neurobehavioral Test Battery (AENTB), which evaluates major neurobehavioral domains and functions, was adopted by the Agency for Toxic Substances and Disease Registry (ATSDR) for use as a basic screening panel in field studies. Pilot testing of the AENTB demonstrated an examiner training requirement of 3-6 practice sessions, a mean total testing time of 58.0 min (SD = 9.6), and, for 9 of the component tests, a sample size requirement of fewer than 140 (alpha = 0.05, 95% power) to detect a 20% difference between study groups. ATSDR administered the AENTB to 467 persons, selected randomly from 1,382 participants in field study sites in three states. Total testing time varied noticeably by participant age and study site, suggesting an ongoing need for site-specific controls in each field study using the AENTB. Also planned is adoption of a pediatric test battery to evaluate the domains and functions most relevant at major stages of child development.