Reassessment of occupational exposure limits.

BACKGROUND

Although the Netherlands currently has its own procedure for evaluating chemical compounds and setting occupational exposure limits (OELs), most of these limits were originally adopted in the 1970s from threshold limit values (TLVs) set by the American Conference of Governmental Industrial Hygienists (ACGIH). However, beginning in the late 1980s, criticism about non-scientific considerations being used to set TLV's suggested that TLVs might not offer sufficient health protection to workers. This situation prompted the Dutch Ministry of Social Affairs and Employment to request that the Health Council of the Netherlands reassess the health protection of MAC values that were contained in the 1994 Dutch MAC list.

METHODS

Criteria documents were prepared for 161 compounds. They were evaluated by a committee of the Health Council of the Netherlands consisting of international experts who reassessed the toxicological hazards of these substances and recommended, whenever possible, health-based OELs. The results of the reassessment by the Health Council were compared with the MAC values of the 1994 Dutch MAC list, ACGIH TLVs, and existing German OELs.

RESULTS

The toxicological database met the committee's criteria for a health-based OEL for only about 40% of the compounds.

CONCLUSIONS

Many older MAC values were either too high or not scientifically supported and therefore not health-based.