Assessment of neurobehavioral performance as a function of current and cumulative occupational lead exposure

A cross sectional field study was planned to assess neurotoxic effects caused by low-level occupational lead exposure. Two groups of 66 workers and 86 controls were examined with a battery including a questionnaire on neurotoxic symptoms, the measure of performance at neurobehavioral testing, the detection of visual contrast sensitivity, and the dosage of serum prolactin. Both current and cumulative exposure to lead were defined. The average PbB was 27.50 +/- 28 microg/dl (median 28, range 6-61) in the exposed and 8.11 +/- 4.47 microg/dl (median 7, range 2-21). The test results were controlled for possible confounders including age, schooling, alcohol and coffee intake. Significant differences were observed between exposed and controls regarding neurotoxic symptoms reporting, the exposed reporting more frequently mood changes and abnormal fatigue. The exposed subjects showed a decreased visual contrast sensitivity, and a marked increase of prolactin secretion. No changes emerged regarding neurobehavioral testing. The alterations observed resulted associated to the current lead exposure and not to the cumulative indices. A safe exposure level was calculated on the basis of dose-response relationship with prolactin alteration, yielding a PbB value of 10 microg/dl.