NEUROTOXICITY IN YOUNG-ADULTS 20 YEARS AFTER CHILDHOOD EXPOSURE TO LEAD - THE BUNKER HILL EXPERIENCE

Objectives-An epidemiological study of young adults was conducted to d etermine whether environmental exposure to lead during childhood was a ssociated with current adverse neurobehavioural effects. Methods-The e xposed group consisted of 281 young adults who had been exposed enviro nmentally to lead as children and the unexposed referent group consist ed of 287 age and sex frequency matched subjects. Information on demog raphics, past and current health, and past exposures to neurotoxicants , and responses to the Swedish Q16 questionnaire were collected by int erview. Standard neurobehavioural and neurophysiological tests were ad ministered by computer or trained technicians. K x ray fluorescence wa s used to estimate tibial bone lead concentrations among the exposed a nd unexposed groups. Associations were examined between the exposed gr oup and referents and tibial bone lead concentration and the neurobeha vioural and neurophysiological outcomes of interest. Results-Among the measures of peripheral nerve function, after controlling for confound ers, sural sensory nerve evoked response amplitude, peroneal motor ner ve compound motor action potential amplitude, vibrotactile thresholds of fingers and toes, and standing steadiness were significantly associ ated with exposure group. Among the neurobehavioural tests, hand-eye c oordination, simple reaction time latency, trails B latency, symbol di git latency, serial digit, and learning error score were also signific antly associated with exposure group after controlling for confounders . Exposed subjects had significantly more neuropsychiatric symptoms th an the referents. Associations between tibial bone lead concentration and scores for vocabulary, vibrotactile thresholds of the fingers, and vibrotactile thresholds of the toes approached significance. Conclusi ons-Significant adverse central and peripheral neurological effects we re found in a group of young adults 20 years after childhood environme ntal exposure to lead when compared with non-exposed controls. The abs ence of a significant association between neurological outcomes and ti bial bone lead concentration, and the presence of significant associat ions between neurological outcomes and exposure group may be due to ei ther the magnitude of measurement uncertainty in K Lt. ray films relat ive to the actual tibial bone lead concentration in these young non-oc cupationally exposed subjects, or uncontrolled confounding of the expo sure group.