Exposure and Risk Assessment of Selected Chemical Hazards in Cabbage and Lettuce

Abstract

The objective of this study was to determine health risks associated with consumption of cabbage and lettuce sampled in an urban industrialized study area. Samples were initially digested in Teflon vessels using HNO3 and H2O2, homogenized in Na2SO4, agitated in a mixture of hexane/acetone, cleaned-up and analyzed in ICP MS in order to quantify toxic heavy metals. The PAH content was also quantified in GC-MS against reference PAH congeners. Food frequency questionnaire designed based on the US EPA format, was used to collect elements of chronic daily intake and information on consumption characteristics of the selected samples. The data was processed in Palisade@Risk-based Microsoft Excel, where distributions were fitted for the elements of chronic daily intake. Exposure quantifications of hazards based on the US EPA guidelines, presented hazard quotients and risks, relative to the respective reference doses and cancer slopes factors (CSF). Incremental lifetime cancer risks (ILTCR) were determined as the product of the CSF of the carcinogens and their chronic exposures. The modal and median mercury exposures were low but the exposures of total PAHs (expressed as benzo[a]pyrene -BaP) were extremely high. The hazard quotients revealed that cadmium and mercury had negligible risks (HQ ≤ 1). Though the median and modal ILTCR showed lead to have low health risk concerns (≤ 10-6), the uncertainty ranging from 0 to 3 out-10-thousand consumers revealed insidous risk unacceptability. Similarly, even though the modal and median values of ILTCR of arsenic appeared acceptable (≤ 10-6), the risk uncertainty ranging from 0 to 6 out-1-thousand consumers, still raise health concerns. The median and modal ILTCR values of BaP suggested both a cautiously acceptable risk (≥ 10-6 ≤ 10-4) and a barely negligible risk (≤ 10-6) levels respectively. Thus, every effort must be made to mitigate the seriously high risks lurking in the study area.