Introduction In combustion ashes and dust in the machine hall of two municipal waste incinerators in Flanders, dioxin-like substances were found. The aim of this study was to explore if exposure to these ashes and dust induced an increased uptake of dioxin-like substances.

Methods 50 subjects working in two municipal waste incinerators participated, comprising 32 maintenance workers exposed to dust and ashes, 7 garage workers and 11 administrative workers. The exposed workers were divided according to seniority (≤10 years. and >10 years.). Serum dioxin-like activity was assessed by chemical-activated luciferase gene expression (CALUX) assay. Following non-occupational factors were assessed by questionnaire: BMI, smoking, living near a road with heavy traffic and nutrition intake.

As dioxins accumulate in the body, higher serum dioxin levels could be expected in the exposed maintenance workers. Therefore, the serum dioxin levels of the maintenance workers group were compared with those of the other groups. Additionally, maintenance workers with ≥10 years. seniority were compared with workers with <10 years. seniority. Mann-Whitney U test and Kruskal-Wallis were used where appropriate.

Results Mean overall serum dioxin level was: 31.4 pg CALUX TEQ/g fat (mean values for the general Flemish population: 35.0–41.8 pg). Maintenance workers had significantly (p<0.05) lower serum dioxin levels (mean 26.9 pg) than garage workers (38.3 pg) and administrative workers (38.8 pg). Maintenance workers with >10 years seniority had lower serum dioxin levels (24.7 pg) than those with ≤10 years seniority (31.5 pg). This difference was not significant.No higher serum dioxin concentrations were found in smokers, high BMI, living near a road with heavy traffic.

Conclusion The results showed no increased dioxin-like serum levels in maintenance workers in the two municipal waste incinerators. These results seems to indicate that there is no additional risk for dioxin exposure in the two considered waste incinerators.