Two-year neurocognitive responses to first occupational lead exposure

Area of Science:

• Environmental Health
• Neuroscience
• Occupational Medicine

Background:

• Lead exposure is a known neurotoxin in children, but its effects on adult cognition at occupational levels remain unclear.
• Longitudinal studies are scarce, hindering understanding of lead's impact on adult neurocognitive function in occupational settings.

Purpose of the Study:

• To investigate the two-year neurocognitive function changes in newly hired adult workers at lead recycling plants.
• To assess the association between blood lead levels and cognitive performance using standardized tests.

Main Methods:

• The Study for Promotion of Health in Recycling Lead (NCT02243904) enrolled workers without prior occupational exposure.
• Neurocognitive function was assessed using the digit-symbol test (DST) and Stroop test (ST) annually.
• Blood lead (BL) levels were measured, and statistical analyses used multivariable-adjusted mixed models.

Main Results:

• The study included 260 participants for DST and 168 for ST, with mean baseline blood lead levels around 4 µg/dL.
• While initial analyses suggested a potential link between increased blood lead and cognitive changes, fully adjusted models showed no statistically significant associations.
• A threefold increase in blood lead over two years did not correlate with a significant decline in cognitive performance.

Conclusions:

• Two years of occupational lead exposure in recycling plant workers, even with rising blood lead levels, was not associated with a meaningful decline in neurocognitive function.
• Findings suggest current occupational exposure limits may protect adult cognitive health, but further research is warranted.