Estimation of metal and organochlorine pesticide exposures and potential health threat by consumption of oysters in Taiwan

Pollutant concentrations detected in oysters from 12 different culture area s of Taiwan (especially for the Hsiangshan area and the Machu Islands) from 1991-98 were evaluated to investigate potential carcinogenic (inorganic As and organochlorine pesticides) and non-carcinogenic (Cu, Zn, Cd and inorga nic As) risk to the public from ingestion of the oysters. The highest geome tric mean (GM) Cu and Zn concentrations of 1108 (range 113-2806) and 1567 ( range 303-3593) mu g/g dry weight were obtained in oysters from the Hsiangs han coastal area. The maximum GM Cd and As concentrations of 6.82 and 19.3 mu g/g dry weight were found in oysters from the Machu Islands area. The p, p'-DDE values range from not detectable in Penghu Islands' oysters to 164 n g/g dry weight in Machu Islands' oysters. The highest tDDT (sum of pp'-DDE. p,p'-DDD and p,p'-DDT) concentrations of 337 and 340 ng/g dry weight were found in oysters from Kimmen and Machu Islands, respectively. A calculated target hazard quotient (THQ; daily intake/reference dose) of 11.4 (based on 139 g oysters/day) for Cu caused by consuming oysters from the Hsiangshan area is higher than that from other areas (range 0.124-5.95). The highest a verage Cu intake from Hsiangshan's oysters for individuals is 11.4 times (i .e. THQ = 11.4) more than that of reference dose (40 mu g/kg/day). However, the maximum THQ values for Cd and As caused by consuming oysters collected from the Machu Islands were 5.57 and 2.63 for Cd and As, respectively. Gen erally, the results of THQ showed that if only the maximally exposed indivi duals were considered, the value of 65.4% for oyster was higher than 1.0 in comparison with reference dose. All cancer risk estimates for inorganic As from consuming oysters were higher than 10(-6) (range from 128x10(-6) to 5 09x10(-6) for maximally exposed individuals and range from 17.1x10(-6) to 6 8.0x10(-6) for typically exposed individuals, respectively); that is the ri sk of the lower end of the range of acceptable risk. The highest risk estim ate for inorganic As was 509x10(-6) for consumption of oysters by Machu Isl ands' residents. The lifetime cancer risks of 19.0x10(-6) for tDDT by consu ming oysters from the Machu Islands was higher than those from the Penghu I slands (0.37x10(-6)). Therefore, the sum of lifetime cancer risks for tDDT and inorganic As had the highest risks (total risk = 528 x 10(-6)) of consu ming oysters from the Machu Islands. Furthermore, a 10(-6) upper limit on l ifetime risk as the health protection standard would require maximum oyster consumption rates of approximately 0.26 g/day. (C) 2000 Elsevier Science L td. All rights reserved.