Cumulative lead exposure may affect brain

A buildup of lead from earlier exposure may be enough to result in greater cognitive problems after age 55, U.S. researchers found. Researchers at the Graduate School of Public Health and the School of Medicine at the University of Pittsburgh followed up on the 1982 Lead Occupational Study, which assessed the cognitive abilities of 288 lead-exposed and 181 non-exposed male workers in eastern Pennsylvania. All the workers were given the Pittsburgh Occupational Exposures Test battery, which includes measures of five primary cognitive domains -- psychomotor speed, spatial function, executive function, general intelligence and learning and memory. In 1982, lead-exposed workers were found to have an average blood lead level of 40 micrograms per deciliter -- well above normal. Pennsylvania workers found to have 25 micrograms per deciliter or more must be taken off the job. The unexposed workers examined in 1982 had an average blood level of 7.2 -- within normal limits. The study, published in the journal Neuropsychology, found that among the lead-exposed workers, men with higher cumulative lead had significantly lower cognitive scores. This linkage was more significant in the older lead-exposed men, of at least age 55. Their cognitive scores were significantly different from those of younger lead-exposed men even when the researchers controlled for current blood levels of lead. Even when men no longer worked at the battery plants, their earlier prolonged exposure was still significant.