Health effects of occupational exposure to acrylamide using hemoglobin adducts as biomarkers of internal dose

Objectives This study assessed the health effects of occupational acrylamid e exposure using hemoglobin (Hb) adducts as biomarkers of internal dose. Methods Two hundred and ten tunnel workers exposed for about 2 months to a chemical-grouting agent containing acrylamide and N-methylolacrylamide unde rwent a health examination. Blood samples were drawn for the analysis of li b adducts of acrylamide. Fifty workers claiming recently developed or deter iorated symptoms of the peripheral nervous system (PNS) were referred to a neurophysiological examination. Workers with Hb-adduct levels exceeding 0.3 nmol/g globin attended follow-up examinations 6, 12, and 18 months after e xposure cessation. Results Forty-seven workers had lib-adduct levels within the normal backgro und range (0.02-0.07 nmol/g globin), while the remaining 163 had increased levels up to a maximum of 17.7 nmol/g globin. Clear-cut dose-response assoc iations were found between the Hb-adduct levels and PNS symptoms. Thirty-ni ne percent of those with Hb-adduct levels exceeding 1 nmol/g globin experie nced tingling or numbness in their hands or feet. A no-observed adverse eff ect level of 0.51 nmol/g globin was estimated for numbness or tingling in t he feet or legs. For 23 workers there was strong evidence of PNS impairment due to occupational exposure to acrylamide. All but two had recovered 18 m onths after the cessation of exposure. Conclusions Occupational exposure to a grouting agent containing acrylamide resulted in PNS symptoms and signs. The use of Hb adducts of acrylamide as a biomarker of internal dose revealed strong dose-response associations. T he PNS symptoms were, however, generally mild, and in almost all cases they were reversible.