Risk assessment for human consumption of perfluorinated compound-contaminated freshwater and marine fish from Hong Kong and Xiamen

Perfluorinated compounds (PFCs) are man-made fluoro-surfactants that are identified as global pollutants and can pose health risks to humans and wildlife. Two aspects of risk assessment were conducted in this study, including exposure and response. Exposure was estimated by using the concentrations of PFCs in fish and applying standard exposure factors. Among different PFCs, PFOS, PFOA, PFNA, PFDA, PFUdA and PFTrDA were detected. Total concentrations of PFC in fish ranged from 0.27-8.4 ng g⁻¹ to 0.37-8.7 ng g⁻¹ respectively in Hong Kong and Xiamen. The calculated hazard ratio (HR) of PFOS for all fish was less than 1.0. However, the HR for mandarin fish in Hong Kong and bighead carp, grass carp and tilapia in Xiamen, had HR values of approximately 0.5, indicating that frequent consumption of these 4 more contaminated fish species might pose an unacceptable risk to human health. Our data support the notion that the released/disposed chemical pollutants into water systems make fish a source of environmental toxicants to humans. The risks and potential effects of PFCs to health of coastal population in the Pearl River Delta are of concern.     

Exposure to PCBs, through inhalation, dermal contact and dust ingestion at Taizhou, China--a major site for recycling transformers

Air samples containing gaseous and particulate phases were collected from e-waste workplaces and residential areas of an intensive e-waste recycling area and compared with a reference site. The highest total concentration of PCBs was detected at transformer recycling workshops (17.6 ng m(-3)), followed by the residential area (3.37 ng m(-3)) at Taizhou, and the lowest was obtained at the residential area of the reference site, Lin'an (0.46 ng m(-3)). The same trend was also observed with regards to PCB levels in dust samples. The highest average PCBs level of 2824 ng g(-1) (dry wt) was found in the transformer recycling workshops, and was significantly higher than that of residential areas of Taizhou (572 ng g(-1) dry wt) and Lin'an (42.4 ng g(-1) dry wt). WHO-PCB-TEQ level in the workshops of Taizhou was 2216 pg TEQ(1998)g(-1) dry wt or 2159 pg TEQ(2005)g(-1) dry wt, due to the high abundance of PCB 126 (21.5 ng g(-1) dry wt), which contributed 97% or 99% of WHO-PCB-TEQs. The estimated intake of PCBs via dust ingestion and dermal absorption by transformer recycling workers were 77.5×10(-5) and 36.0×10(-5) pg WHO-PCB-TEQ(1998)kg(-1)d(-1), and 67.3×10(-5) and 31.3×10(-5) pg WHO-PCB-TEQ(2005)kg(-1)d(-1), respectively.     

Cadmium accumulation in and tolerance of rice (Oryza sativa L.) varieties with different rates of radial oxygen loss

Cadmium (Cd) uptake and tolerance were investigated among 20 rice cultivars based on a field experiment (1.2 mg Cd kg⁻¹ in soil) and a soil pot trial (control, 100 mg Cd kg⁻¹), and rates of radial oxygen loss (ROL) were measured under a deoxygenated solution. Significant differences were found among the cultivars in: (1) brown rice Cd concentrations (0.11-0.29 mg kg⁻¹) in a field soil, (2) grain Cd tolerance (34-113%) and concentrations (2.1-6.5 mg kg⁻¹) in a pot trial, and (3) rates of ROL (15-31 mmol O₂ kg⁻¹ root d.w. h⁻¹). Target hazard quotients were calculated for the field experiment to assess potential Cd risk. Significant negative relationships were found between rates of ROL and concentrations of Cd in brown rice or straw under field and greenhouse conditions, indicating that rice cultivars with higher rates of ROL had higher capacities for limiting the transfer of Cd to rice and straw.     

Responses of Sesbania rostrata and S. cannabina to Pb, Zn, Cu and Cd toxicities

Responses of Sesbania rostrata and S. cannabina to Pb, Zn, Cu and Cd toxicities were assessed by a seed-suspending seedbed(SSS) approach. The results showed that the SSS approach was suitable for testing the tolerance of a plant to the stress of toxic metals. The endpoints include seed germination success, straightened radicle and hypocotyl of the seedlings from the seeds. The measurements could be done easily and accurately. It was found that the elongation of radicle was the most sensitive indicator to the stress of heavy metals among the endpoints. When exposure to lower or medium concentrations of Pb, Zn, and Cd, the development of the lateral roots were favorable. Species of S. rostrata was more tolerant than S. cannabina to the heavy metals, especially to Zn and Cd. The ED50 of Pb, Zn, Cu and Cd were 32.90, .5.32, 4.40 and 12.00 μg/ml for S. rostrata,respectively, and they were 30.11, 2.87, 4.0.5 and 4.94 μg/ml respectively for S. cannabina.     

Exposure to polybrominated diphenyl ethers associated with consumption of marine and freshwater fish in Hong Kong

Concentrations of polybrominated diphenyl ethers (PBDEs) in market fish have not previously been reported in Hong Kong. Axial and ventral muscles from 10 each common species of freshwater and marine fish purchased from markets in Hong Kong were analyzed for 22 PBDEs. Among the 10 freshwater fish species, spotted snakehead (Channa maculate) contained the highest level of PBDEs in ventral muscle (130 ng g(-1) wet wt.). For marine fish, bigeye (Priacanthus macracanthus) showed significantly higher levels of PBDEs (60.7 ng g(-1)wet wt. in ventral tissue) than all other marine species. The levels of PBDEs in fish samples ranged from 0.53 to 130 ng g(-1)wetwt. The tetrabrominated congener BDE-47 and pentabrominated BDE-99 were the predominant congeners, which accounted for 27% and 30%, respectively, of the total PBDEs. Daily PBDE intake was calculated according to the different fish consumption rate for Hong Kong consumers, and the results ranged from 222 to 1198 ng day(-1) for marine fish and 403-2170 ng day(-1) for freshwater fish. The daily PBDE intake from fish reported here were higher than those reported from the United States (8.94-15.7 ng day(-1)) and Europe (14-23.1 ng day(-1)).     

Bioaccessibility of polychlorinated biphenyls in different foods using an in vitro digestion method

Bioaccessibility of organic pollutants in food is important for exposure estimation and risk assessment. An in vitro enzyme digestion experiment was carried out to analyze the bioaccessibility of PCBs in different foods including freshwater fish (bighead carp and oriental weather fish) and vegetables (spinach and cabbage). The results indicated that the bioaccessibility of PCBs in freshwater fish (3%) was much lower than that in leafy vegetables (25%). Based on field survey, the daily exposure TEQ value from these two types of food was 17.9 pg/kg bw/day. However, when bioaccessibility was taken into consideration, the value decreased to 0.61 pg/kg bw/day. Therefore, the forms of PCBs existing in food strongly influenced the bioavailability for humans, which may have important implications on dietary exposure. To our knowledge, this is the first paper to illustrate the bioaccessibility of PCBs in different foods using an in vitro digestion method.     

Alternative immunofluorescent labeling of Cryptosporidium parvum in water samples using semiconductor quantum dots

The application of immunofluorescent labeling using quantum dots for detection of inactivated Cryptosporidium parvum oocysts in spiked water samples (reservoir water, treated wastewater effluent, permeate of a membrane bioreactor, and tap water) provided more consistent results compared with the organic fluorophores label. The varying degree of particles present in the different water samples (with turbidity ranging from 0.2 to 6.1 NTU) in nonconcentrated water samples had insignificant interference on the labeled counts (2-sample t-tests, p > 0.236) using the quantum dot label, while the quantum dot label provided an advantage of approximately 50% lower interference in concentrated water samples compared with the organic fluorophores label.     

Acidification of lead/zinc mine tailings and its effect on heavy metal mobility

The acid-forming potential of lead/zinc (Pb/Zn) mine tailings at Lechang City of Guangdong Province was studied using both net acid generation (NAG) and acid-base accounting (ABA) methods. The pyritic and total sulfur contents of the tailings were 12.6% and 18.7%, respectively. The mean acid neutralization capacity (ANC) was 63.5 kg H2SO4/t while three oxidized tailings samples had an ANC less than zero. The NAG and net acid production potential (NAPP) values were 220 and 326 kg H2SO4/t, and both the NAG and NAPP results indicated that the tailings had a high acid-forming potential. NAG was more accurate than NAPP in predicting acid-forming potential of the tailings due to uncompleted oxidization of pyritic sulfur. Analysis of samples from two profile tests indicated that acidification mainly occurred at the surface (0-20 cm) and had little effects at deep layer of the tailings. Total concentrations of Pb, Zn, Cu, and Cd were increased greatly with depth at the acidified tailings profile, while heavy metal concentrations at different depths of nonacidified tailings profile were similar. The results indicated that depletion of heavy metals at the acidified surface was due to acidification. The diethylenetetramine pentaacetic acid (DTPA)-extractable Pb, Zn, Cu, and Cd concentrations of acidified tailings surface (0-20 cm) were significantly higher than those of nonacidified tailings, which further revealed that acidification enhanced the mobility of heavy metals in the tailings.     

Systematic study on the relationship between particulate matter and microbial counts in hospital operating rooms

Environmental Science and Pollution Research - In this study, a systematic procedure for establishing the relationship between particulate matter (PM) and microbial counts in four operating rooms...