Health Risk Assessment of a Modern Municipal Waste Incinerator. Céline Boudet and Denis Zmirou, Public Health Laboratory, Domaine de la Merci, GEDEXE, Grenoble University Medical School, 38706 La Tronche, France, telephone/fax +33476637419, e-mail boudet@ujf-grenoble.fr; Mauricette Laffond, GRECA (Applied Chemistry Research Group), Grenoble University, France; Franck Balducci, Public Health Laboratory, GEDEXE, Grenoble University Medical School, France; and Jean-Louis Benoit-Guyod, GEDEXE, Grenoble University School of Pharmacy, France
Within the process of modernization of the municipal waste incinerator (MWI, maximum capacity of 180 000 tons per year) of Metropolitan Grenoble (405 000 inhabitants), in France, a risk assessment was conducted, based on four tracer pollutants : two volatile organic compounds (benzene and trichloroethane) and two heavy metals (nickel and cadmium, measured in particles).
A Gaussian plume dispersion model, applied to maximum emissions measured at the MWI stacks, was used to estimate the distribution of these pollutants’ concentrations throughout the metropolitan area. A random sample telephone survey (570) gathered data on time-activity patterns within the population, according to demographic characteristics. Life-long exposure was assessed as time-space weighted averages of ambient air concentrations. Inhalation alone was considered because, in the Grenoble urban setting, other routes of exposure are not likely. A Monte Carlo simulation was used to describe probability distributions of exposures and risks.
The median of the life-long personal exposures distribution to MWI benzene was 3.2.10-3 µg/m3 (20th and 80th percentiles distribution = 1.5.10-3 and 6.5.10-3 µg/m3), yielding a 2.6.10-8 carcinogenic risk (1.2.10-8 ; 5.4.10-8). For nickel, the corresponding life-time exposures and cancer risks were 1.8.10-2 µg/m3 (0.9.10-2 ; 3.6.10-2 µg/m3) and 8.6.10-6 (4.3.10-6 ; 17.3.10-6). Average inhalation exposure to cadmium emitted by the MWI represented at most 36% of the WHO Air Quality Guideline (5 ng/m3), while there was more than a 107 security factor between the EPA NOAEL and average exposure estimates to trichloroethane.
Although dioxins were not studied, nor mercury volatile metal, that could show greater attributable life-long risks, these minute exposure and risk estimates are in accord with other studies on modern MWIs meeting recent emission regulations.
Acknowledgments : This work was supported by a grant from ADEME (Agency for Environment and Energy, Paris, France) ; it was conducted within the collaborative group GRIDEC (Groupe de Recherche Interdisciplinaire sur les Déchets). The authors are grateful to Prof. J. Evans (Harvard School of Public Health) for his thoughtful advice.
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