A new study has outlined the risks of cognitive problems during old age in adults who have been exposed to lead during their work life.
For the study, the researchers analysed the data of the 1982 Lead Occupational Study, which assessed the cognitive abilities of 288 lead-exposed and 181 non-exposed male workers in eastern Pennsylvania.
The lead-exposed workers came from three lead battery plants; the unexposed control workers made truck chassis at a nearby location.
In 1982, lead-exposed workers were found to have an average blood lead level of 40 micrograms per deciliter (ug/dL), well above normal.
The unexposed workers had an average blood level of 7.2, within normal limits.
In 2004, the current study followed up with 83 of the original lead-exposed workers and 51 of the original non-exposed workers. The researchers assessed the participants' cognitive performance.
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. In other words, even when men no longer worked at the battery plants, their earlier prolonged exposure was enough to matter.
The men who built lead batteries were exposed to it in the air and through their skin.
Other occupations, including semiconductor fabrication, ceramics, welding and soldering, and some construction work, also may expose workers.
The authors wrote: ''Increased prevention measures in work environments will be necessary to reduce [lead exposure] to zero and decrease risk of cognitive decline.''
The report appears in the January issue of Neuropsychology.