To clarify the groundwater–soil–crop relationship with respect to arsenic (As) contamination, As concentration was measured in tubewell (TW) water, surface soil from farmyards and paddy fields, and fresh taro (Colocasia esculenta) leaves from farmyards in the farming villages of Bangladesh. The As concentration in TW water from farmyards was at least four times higher than the Bangladesh drinking water standard, and the concentration in fresh taro leaves was equal to or higher than those reported previously for leafy vegetables in Bangladesh. As concentration of surface soils in both farmyards and paddy fields was positively correlated with that of the TW water. Further, the concentration in surface soil was positively correlated with levels in fresh taro leaves in the farmyard. This study, therefore, clarified the groundwater–soil–crop relationship in farmyards and the relationship between groundwater–soil in paddy fields to assess the extent of As contamination in Bangladeshi villages. By extracting arsenic contaminated groundwater from a well, surface soil surrounding the well and crops planted in the surface soil became contaminated with arsenic.

Consumption of food crops contaminated with heavy metals is a major food chain route for human exposure. We studied the health risks of heavy metals in contaminated food crops irrigated with wastewater. Results indicate that there is a substantial buildup of heavy metals in wastewater-irrigated soils, collected from Beijing, China. Heavy metal concentrations in plants grown in wastewater-irrigated soils were significantly higher (P <= 0.001) than in plants grown in the reference soil, and exceeded the permissible limits set by the State Environmental Protection Administration (SEPA) in China and the World Health Organization (WHO). Furthermore, this study highlights that both adults and children consuming food crops grown in wastewater-irrigated soils ingest significant amount of the metals studied. However, health risk index values of less than 1 indicate a relative absence of health risks associated with the ingestion of contaminated vegetables. Long-term wastewater irrigation leads to buildup of heavy metals in soils and food crops.

Inorganic arsenic is a chronic exposure carcinogen. Analysis of UK baby rice revealed a median inorganic arsenic content (n = 17) of 0.11 mg/kg. By plotting inorganic arsenic against total arsenic, it was found that inorganic concentrations increased linearly up to 0.25 mg/kg total arsenic, then plateaued at 0.16 mg/kg at higher total arsenic concentrations. Inorganic arsenic intake by babies (4-12 months) was considered with respect to current dietary ingestion regulations. It was found that 35% of the baby rice samples analysed would be illegal for sale in China which has regulatory limit of 0.15 mg/kg inorganic arsenic. EU and US food regulations on arsenic are non-existent. When baby inorganic arsenic intake from rice was considered, median consumption (expressed as μg/kg/d) was higher than drinking water maximum exposures predicted for adults in these regions when water intake was expressed on a bodyweight basis. Median consumption of organic arsenic levels for UK babies from baby rice is above threshold considered safe.

The induction of cytochrome P4501A-mediated activity (e.g. ethoxyresorufin-O-deethylation, EROD) has been used as a biomarker for monitoring fish exposure to AhR-receptor ligands such as polycyclic aromatic hydrocarbons (PAH), polychlorinated biphenyls (PCB) and polychlorinated dibenzo-dioxins/furans (PCDD/Fs). In this study we found that hepatic EROD is induced in fish (“Nile tilapia”, Oreochromis niloticus and “acará”, Geophagus brasiliensis) from the Guandu River (7-17-fold) and Jacarepaguá Lake (7-fold), Rio de Janeiro, Brazil. Since both cichlid fish are consumed by the local population and the Guandu River is the main source of the drinking water supply for the greater Rio de Janeiro metropolitan area, pollution by cytochrome P4501A-inducing chemicals is a cause for concern and should be further investigated in sediments, water and biota. We additionally showed that EROD activity in the fish liver post-mitochondrial supernatant--simpler, cheaper and less time consuming to prepare than the microsomal fraction--is sufficiently sensitive for monitoring purposes. Increased EROD activity in the liver of cichlid fishes indicated that Guandu River, the source of drinking water supply for Rio de Janeiro is polluted by CYP1A-inducing chemicals.

Fifty fish samples were collected from the Pearl River estuary (PRE) and Daya Bay, South China and were analyzed for DDTs, HCHs, chlordanes and polybrominated biphenyl ethers (PBDEs). Except the high concentrations of DDT observed in fishes, the concentrations of HCHs, chlordanes and PBDEs were low when compared to other regions. BDE-47 was the predominant PBDE congener and the BDE-209 concentrations were relatively low, despite its high concentration in surface sediments. The absence of significant increase of DDT, HCH, chlordane and PBDE concentrations towards higher δ15N values, as well as the lack of a significant correlation (p < 0.1) between log concentrations (lipid normalized) and δ15N, may indicate a weak biomagnification of these chemicals in the food webs. Good agreement was observed between their concentrations and lipid contents of the organisms. Bioconcentration was suggested to be responsible for the accumulation of OCPs and PBDEs in the lower trophic organisms in the studied subtropical waters. Bioconcentration was suggested to be responsible for the accumulation of OCPs and PBDEs in the lower trophic organisms of subtropical waters.

Uptake of waterborne Cd, Co, Mn and Zn was determined in laboratory experiments using radiotracer techniques (109Cd, 57Co, 54Mn and 65Zn). Labelled Zn was mainly accumulated in the digestive gland (65%) and Co in kidneys (81%); Cd and Mn were similarly distributed in digestive gland and gills. In a complementary field study, Ag, As, Cd, Co, Cr, Cu, Fe, Mn, Ni, and Zn were analysed in scallops collected at two stations showing different contamination levels. Digestive gland and kidneys displayed the highest concentrations. Ag, As, Cd, and Fe differed in soft tissues from the two stations, suggesting that Comptopallium radula could be a valuable local biomonitor species for these elements. Low Mn and Zn concentrations found in kidneys suggest that their content in calcium-phosphate concretions differs from the other pectinids. Preliminary risk considerations suggest that As would be the only element potentially leading to exposure of concern for seafood consumers. This study investigates metal accumulation behaviour in the tropical scallop Comptopallium radula and preliminary risk assessment for consumers.

An analytical procedure for the determination of Hg in otter (Lontra longicaudis) feces was developed, to separate fish scales for the identification of the animal diet. Samples were washed with ultra-pure water and the suspension was sampled and transferred for digestion. The solubilization was performed with nitric-perchloric acid mixture, and detection carried out by the atomic fluorescence spectrometry (AFS). The quality of the analytical procedure was assessed by analyzing in-house standard solutions and certified reference materials. Total Hg concentrations were in the range of 7.6-156 ng g-1 (July 2004), 25.6-277 ng g-1 (January 2005) and 14.6-744 ng g-1 (May 2005) that is approximately the same order of magnitude for all samples collected in two reservoirs at the Tiete River, Brazil. Although Hg concentrations varied with sampling periods and diet, high levels were correlated to the percentage of carnivorous fish scales present in the otter feces. The importance of otter feces preparation for Hg analysis, focusing the food web.

The objective of this study was to investigate the accumulation of selenium in lakes downstream of a uranium mine operation in northern Saskatchewan, Canada. Selenium concentrations in sediment and biota were elevated in exposure areas even though water concentrations were low (<5 μg/L). The pattern (from smallest to largest) of selenium accumulation was: periphyton < plankton and filterer invertebrates < detritivore and predator invertebrates < small bodied (forage) fish and predatory fish. Biomagnification of selenium resulted in an approximately 1.5–6 fold increase in the selenium content between plankton, invertebrates and forage fish. However, no biomagnification was observed between forage fish and predatory fish. Selenium content in organisms from exposure areas exceeded the proposed 3–11 μg/g (dry weight) dietary toxicity threshold for fish, suggesting that the selenium released into these aquatic systems has the potential to bioaccumulate and reach levels that could impair fish reproduction. Selenium bioaccumulation patterns in a north temperate, cold water aquatic ecosystem were similar to those reported from warm water systems.

We determined the concentrations and residue patterns of 20 persistent organochlorine pesticides (OCPs), including hexachlorocyclohexanes (HCHs), hexachlorobenzene, dichlorodiphenyltrichloroethanes (DDTs), chlordane-related compounds (CHLs), mirex, dieldrin, endrin, and aldrin, in muscle of rainbow trout from Lake Mashu, Japan. Total concentrations of OCPs varied from 1.0 to 132 ng g-¹ lipid weight. α-HCH was the most prevalent OCP contaminant in the fish muscle. Using the daily fish consumption in Japan (95.2 g), the mean weight of a Japanese adult (50.0 kg), and residual pesticide concentrations, we calculated the estimated daily intakes of γ-HCH, DDTs, CHLs, and dieldrin for humans to be 0.39, 0.48, 0.68, and 0.08 ng kg-¹ day-¹, respectively. Judging from acceptable daily intakes established by the Food and Agriculture Organization of the United Nations and the World Health Organization, we believe that these OCP levels would not adversely affect human health.