Manganese exposure in foundry furnacemen and scrap recycling workers

Objectives: Cast iron products are alloyed with small quantities of mangane se, and foundry furnacemen are potentially exposed to manganese during tapp ing and handling of smelts. Manganese is a neurotoxic substance that accumu lates in the central nervous system, where it may cause a neurological diso rder that bears many similarities to Parkinson's disease. The aim of the st udy was to investigate the sources and levels of manganese exposure in foun dry furnacemen by a combined measuring of blood-manganese (B-Mn) and mangan ese in ambient air (air-Mn). Methods: During a period of 16 months, Air-Mn and B-Mn (denoted 'exposure values') were measured involving 24 furnacemen employed in three small size foundries and 21 scrap recycling workers from one plant. In the study period, 18 furnacemen had B-Mn measured 3-4 weeks a fter decreasing or stopping exposure (denoted 'post-exposure values'). The reference group for the B-Mn measurements consisted of 90 Danish male subje cts. Results: Furnacemen who work in insufficiently ventilated smelting dep artments inhale, absorb, and retain significant amounts of manganese in the ir blood (approx. 2.5-5 mu g/l above reference values) despite a generally low measured airborne level of manganese fumes (0.002-0.064 mg/m(3)). The ' exposure values' compared with 'post-exposure values' revealed a significan t decrease in the B-Mn (on average 3.7 mu g/l) level of the most exposed fu rnacemen. Two persons in our study were suspected of suffering clinically s ubacute manganese intoxication as both had B-Mn levels beyond the normal li mit (25 and 29 mu g/l, respectively). The potential problem disappeared com pletely after cessation of exposure, and the B-Mn levels decreased to 9.4 a nd 14.1 mu g/l, respectively. Conclusions: Risk assessment based on combine d measurements of B-Mn and air-Mn seems to be valid in the interpretation o f workers' hazard. Our study indicates that B-Mn may be a valuable paramete r for estimating recent exposure (within 1-2 weeks). However, more knowledg e is needed about the B-Mn level and its relation to neurological symptoms.