Neurotoxicity from airborne chemicals around a superfund site

A pilot investigation had shown that 88 people living within 2.4 km of a waste chemical disposal and oil-reprocessing facility which operated from 1966 to 1983 had reduced neurobehavioral performance compared to 66 regional referents. A geographic model of dispersal predicted less effect with greater distance from the distilling. To explore this gradient and the boundaries of the adverse effects, we tested 408 residents in random proportional samples of concentric zones from the center out to 4.8 km that were divided by compass octants. Reaction times, balance, blink reflex latency, color discrimination, Culture Fair, pegboard, and Trail Making A and B were measured. Patients completed a Profile of Mood States, frequency of 33 symptoms, and medical, occupational, and exposure histories. Distance and direction from the site and duration of residence were examined for effect on each test score by stepwise linear regression. Exposed subjects' had diminished reaction time, balance, color score, and scores for Culture Fair, pegboard, and Trail Making A and B compared to referents. Functional impairment was not correlated with distance or direction from the site but subjects with short durations of residence had better function on one test. Combinations of these factors were not predictive.