Influência da taxa de dose potencial variável em áreas contaminadas no cálculo de risco à saúde humana

Abstract

Abstract: In the management of sites contaminated, human health risk assessment is an important step on the characterization the potential effects of toxic substances on human health. To define the probable concentration to which the receptor can contact during exposure, traditional methodologies for risk assessment (e.g., RBCA) assume that the receptors are exposed to a maximum and constant concentration throughout the entire exposure duration (25 - 30 years). A field experiment with controlled release of gasoline with ethanol, monitored over a long period of time, was used as a case study in order to evaluate the influence of variation of contaminants concentrations in the quantification of human health risk, from its release in groundwater until its complete attenuation. Human health risk of benzene and toluene in the experimental area were calculated from the variable potential dose rate. The results of the experimental area showed that the maximum exposure concentrations of benzene and toluene were present during a short period when the exposure duration of 25 years was considered. It was observed that the conventional approach of risk calculation presented results with differences of two orders of magnitude, depending on the sampling period, not reflecting the temporal variation of concentrations since the beginning of the experiment until complete attenuation of contaminants. Under these conditions, the availability of a complementary procedure for quantifying risk focusing on the variation of potential dose rate in models that simulate transport and transformation mechanisms may provide risk values according to sitespecific conditions, reducing the uncertainties in the quantification of risk with regard to the choice of the representative concentration of the area, assisting in decision-making technologies more suitable technological alternatives to recover impacted areas