Health risk assessment of heavy metals in Cyprinus carpio (Cyprinidae) from the upper Mekong River

The purposes of this research are to quantify the concentration of heavy metals (Zn, Cu, As, Pb, Cd, and Hg) in the water and fish tissues of common carp (Cyprinus carpio) in the upper Mekong River and to thereby elucidate the potential dietary health risks from fish consumption of local residents. Surface water and fish tissues (gill, muscle, liver, and intestine) from four representative sample areas (influence by a cascade of four dams) along the river were analyzed for heavy metal concentrations. Results revealed that the levels of heavy metals in fish were tissue-dependent. The highest Cu and As levels were found in the liver; the highest Zn and Pb levels occurred in the intestine, and the highest Hg level was found in the muscle. The total target hazard quotient (THQ) value for residents is > 1 for long-term fish consumption, and local residents are, therefore, exposed to a significant health risk. Results from the current study provide an overall understanding of the spatial and tissue distribution of heavy metals in water and fish body along the upper Mekong River under the influence of cascade dams and highlight the potential health risk of As for the local residents of long-term fish consumption.

     

Human health risk assessment of organochlorines associated with fish consumption in a coastal city in China

Food consumption is an important route of human exposure to organochlorines (OCs). In order to assess the potential health risks associated with these contaminants due to fish consumption, five species of fish were collected from a local market in Zhoushan City, an island in the East China Sea. Dioxin-like compounds, such as polychlorinated dibenzo-p-dioxins/ dibenzofurans, in the fish samples were screened by H4IIE-luc cell bioassay, and the concentrations of specific organochlorines were measured by gas chromatograph-electron capture detector (GC-ECD). The bioassay results indicated that concentrations of dioxin-like compounds in the fish samples were below detection limit (0.64 pg/mL). The concentrations of OC pesticides and PCBs ranged from 0.67 to 13 and 0.24 to 1.4 ng/g wet wt., respectively. Significantly, concentrations of p,p'-DDE in fish meat were comparatively high (average 3.9 ng/g wet wt.) compared with the other OC pesticides. The daily fish consumption, based on a dietary survey conducted among 160 local healthy residents, was determined to be 105 g/person. The relevant cancer benchmark concentrations of HCB, dieldrin, chlordane, DDTs and PCBs were 0.36, 0.04, 1.6, 1.7, and 0.29 ng/kg per day, respectively, based on the local diet. The hazard ratios (HRs), based on non-cancer endpoints were all less than 1.0, while the HRs based on cancer were greater than 1.0 for certain contaminants based on the 95th centile concentration in fish tissue.     

Risk assessment of dioxins and dioxin-like PCBs in food--comments by the German Federal Environmental Agency

Human health risk assessments for dioxins and dioxin-like PCBs (with the exception of the one by US-EPA) recommend health based exposure limits within the range of 1-4 pg WHO-TEQ/kg bw per day. As all humans are exposed to measurable levels of dioxins and related substances, the determination of the tolerated daily intake is a very significant decision and may influence limit values guiding risk reduction measures and target levels. The proposed TDI has to protect all human subpopulations. In the case of dioxin this is particularly important as the exposure of infants through breast-feeding may exceed the exposure of adults by one or two orders of magnitude. An overview of recently recommended limit values (WHO, SCF, JECFA) for PCDDs, PCDFs and dioxin-like PCBs using WHO-TEFs shows the common feature that the values were derived only from non carcinogenic endpoints. In November 2000 the Scientific Committee on Food of the European Commission published an 'Opinion of the SCF on the Risk Assessment of Dioxins and Dioxin-like PCBs in Food' [SCF, Scientific Committee on Food 2000. Opinion of the SCF on the risk assessment of dioxins and dioxin-like PCBs in food. European Commission, Brussels, Adopted on November 2000 http://europa.eu.int/comm/food/fs/sc/scf/out78_en.pdf]. On the basis of this extensive review of data and experimental results the Committee recommended a temporary tolerable weekly intake (t-TWI) of 7 pg WHO-TEQ/kg bw. Only six months later the SCF carried out a re-evaluation of its t-TWI from November 2000. The reconsideration of 'pivotal studies' led to the situation that the re-assessment is now based only on rat studies which investigated only reproductive effects only on male offspring and, in addition, three of these studies are single dose studies at gestational day 15. Applying an overall uncertainty factor of 10 to the LOAEL derived estimated human daily intakes (EHDI) the SCF concluded that 14 pg/kg bw per week should be considered as a tolerable intake for 2,3,7,8-TCDD. The SCF stated that on a body weight basis, the dioxin intake of breast-fed infants has been estimated to be one to two orders of magnitude higher than the average adult intake. Recent German data suggest that the body burden of formerly breast-fed children aged 9-11 is still about 30% higher than those of their formula-fed age-mates. As breast-feeding has measurable benefits for neurological and immunological development, formula feeding cannot be recommended as an alternative to lower dioxin intake. So the only remaining way to lower the dioxin uptake is to drastically reduce the background exposure of the general population. It is acknowledged that any recommendation of a precise number for a TDI is flawed by uncertainties and the possibility of different weight being given to the studies of relevance. The determination of the TDI has influence on all regulatory limit values that are based on the TDI value. A higher TDI lowers the level of protection for humans. It is proposed by the German Federal Environmental Agency that the TDI should be reassessed in a process transparent to the public and on the basis of all relevant endpoints from animal experiments and human epidemiology, including the assessment of cancer risks.     

Human exposure to dioxins through the diet in Catalonia,Spain: carcinogenic and non-carcinogenic risk

The main objectives of this study were to estimate the dietary intake of dioxins by the population of Catalonia, Spain, to determine which food groups showed the greatest contribution to this intake, and to assess the health risks potentially associated with the dietary dioxin intake. From June to August 2000, food samples were randomly acquired in seven cities of Catalonia. Dioxin concentrations were determined in 108 samples belonging to the following groups: vegetables, fruits, pulses, cereals, fish and shellfish, meats and meat products, eggs, milk and dairy products, and oils and fats. Estimates of average daily food consumption were obtained from recent studies. Total dietary intake of dioxins for the general population of Catalonia was estimated to be 95.4 pg WHO-TEQ/day (78.4 pg I-TEQ/day), with fish and shellfish (31%), diary products (25%), cereals (14%) and meat (13%) showing the greatest percentages of contribution to dioxin intake. The contribution of all the rest of food groups to the total dietary intake was under 20%. The non-carcinogenic risk index of dioxin intake through the diet was in the range 0.34-1.36, while the carcinogenic risk level was 1,360 excess cancer over a lifetime of 70 years. Our results corroborate the decreasing tendency in dietary intake of dioxins found in recent studies (2000-2001) from various countries.     

Maternal-fetal distribution and transfer of dioxins in pregnant women in Japan, and attempts to reduce maternal transfer with Chlorella (Chlorella pyrenoidosa) supplements

Dioxins can be transferred from mother to fetus via the placenta, or to nursing infants via breast milk, potentially causing developmental health problems in children. To assess pediatric health risks from dioxins, exposure of mothers and children to dioxins must be clarified. Methods of reducing maternal transfer of dioxins should also be investigated. Concentrations of 28 dioxin (polychlorinated dibenzo-p-dioxins, polychlorinated dibenzofurans, and co-planar polychlorinated biphenyls) congeners in blood, adipose tissue, breast milk, cord blood and placenta collected from 44 pregnant Japanese women were measured. In addition, to investigate potential reductions in maternal transfer of dioxins, 23 pregnant women were instructed to take Chlorella pyrenoidosa supplements during pregnancy. Correlations were observed between dioxin total toxic equivalents (total TEQ) in blood and total TEQ in adipose tissue (r=0.913, P<0.0001), breast milk (r=0.695, P=0.0007), and cord blood (r=0.759, P<0.0001). Dioxin levels transferred to fetuses and nursing infants reflect cumulative maternal concentrations of dioxins. A linear regression equation was introduced to predict total TEQ in breast milk and cord blood from dioxin levels in maternal blood, which should prove useful in evaluating fetal and infant risk of dioxin exposure. Total TEQ in cord blood were approximately 26% lower than in maternal blood (P<0.0001). The results of this study suggest that transplacental transfer differs depending on the dioxin congener. Total TEQ in breast milk were approximately 30% lower in the Chlorella group than in controls (P=0.0113). This finding suggests that maternal transfer of dioxins can be reduced using dietary measures such as Chlorella supplements.     

Export of toxic chemicals - a review of the case of uncontrolled electronic-waste recycling

This paper reviews the concentrations of persistent organic pollutants such as flame retardants (PBDEs), dioxins/furans (PCDD/Fs), polycyclic aromatic hydrocarbons (PAHs), polychlorinated biphenyls (PCBs) and heavy metals/metalloid concentrations of different environmental media at Guiyu, a traditional rice-growing village located in southeastern Guangdong Province (PR China), which has turned into an intensive electronic-waste (e-waste) recycling site. Incomplete combustion of e-waste in open air and dumping of processed materials are the major sources of various toxic chemicals. By comparing with existing data available in other areas and also guidelines adopted in different countries, it is obvious that the environment is highly contaminated by these toxic chemicals derived from the recycling processes. For example, the monthly concentration of the sum of 22 PBDE congeners contained in PM(2.5) (16.8ngm(-3)) of air samples at Guiyu was 100 times higher than published data. In order to safeguard the environment and human health, detailed investigations are urgently needed, especially on tracking the exposure pathways of different toxic chemicals which may affect the workers and local residents especially mothers, infants and children.     

Dioxins: WHO's tolerable daily intake (TDI) revisited

In December 1990, the World Health Organization (WHO) established a tolerable daily intake (TDI) of 10 pg/kg b.w. (body weight) for TCDD, based on liver toxicity, reproductive effects and immunotoxicity in experimental animals, and making use of kinetic data in humans and experimental animals. Since then new epidemiological and toxicological data have emerged, in particular with respect to neurodevelopmental and endocrine effects of dioxin. Therefore, the European Centre for Environment and Health of the World Health Organization (WHO-ECEH) and the International Programme on Chemical Safety (IPCS) jointly organized a consultation on the "Assessment of the health risk of dioxins: re-evaluation of the TDI", May 1998, Geneva, Switzerland. The participants discussed the health risks for infants, cancer and non-cancer endpoints in humans and animals, mechanistic aspects, kinetic behaviour, modelling, exposure, and the applicability of the toxic equivalency (TEQ) concept. For the health risk assessment of dioxin-like compounds, the WHO Consultation focused on the most sensitive effects that are considered adverse (hormonal, reproductive and developmental effects) seen at low doses in animal studies (rats and monkeys). Human daily intakes corresponding with body burdens similar to those associated with adverse effects in animals could be estimated to be in the range of 14-37 pg/kg b.w./day. To arrive at a TDI expressed as TEQ, a composite uncertainty factor of 10 was recommended. By applying this uncertainty factor a TDI range of 1-4 pg TEQs/kg body weight was established. An extensive executive summary of the results of this WHO Consultation with all the underlying background documents will be published in Food Additives and Contaminants (in press).     

Concentration and health risk evaluation of heavy metals in market-sold vegetables and fishes based on questionnaires in Beijing,China

Concentrations of heavy metals (As, Cd, Pb, Cu, Ni, Fe, Mn, and Zn) in market vegetables and fishes in Beijing, China, are investigated, and their health risk to local consumers is evaluated by calculating the target hazard quotient (THQ). The heavy metal concentrations in vegetables and fishes ranged from not detectable (ND) to 0.21 mg/kg fresh weight (f.w.) (As), ND to 0.10 mg/kg f.w. (Cd), and n.d to 0.57 mg/kg f.w. (Pb), with average concentrations of 0.17, 0.04, and 0.24 mg/kg f.w., respectively. The measured concentrations of As, Cd, Pb, Cu, Ni, Fe, Mn, and Zn are generally lower than the safety limits given by the Chinese regulation safety and quality standards of agriculture products (GB2762-2012). As, Cd, and Pb contaminations are found in vegetables and fishes. The exceeding standard rates are 19 % for As, 3 % for Cd, and 25 % for Pb. Pb contaminations are found quite focused on the fish samples from traditional agri-product markets. The paper further analyzed the health risk of heavy metals in vegetables and fishes respectively from supermarkets and traditional agri-product markets; the results showed that the fishes of traditional agri-product markets have higher health risk, while the supermarkets have vegetables of higher heavy metal risk, and the supervision should be strengthened in the fish supply channels in traditional agri-product markets.     

Dioxin exposure and public health in Chapaevsk, Russia

One of the largest environmental polluters in Chapaevsk (Samara Region, Russia) is the Middle Volga chemical plant. From 1967 to 1987, it produced hexachlorocyclohexane (lindane) and its derivatives. Currently, it produces crop protection chemicals (liquid chlorine acids, methyl chloroform, vinyl chloride, and some other chemicals). Dioxins were detected in air (0.116 pg/m3), in soil (8.9-298 ng/kg), in the town's drinking water (28.4-74.1 pg/liter), and in the cow's milk (the content of 2,3,7,8-TCDD was 17.32 pg TEQ/g fat). The mean content of dioxins in seven pooled samples of human milk (40 individual trials) was 42.26 pg TEQ/g fat, in four female workers' blood samples -412.4 pg TEQ/g fat, in six residents blood samples (those who lived 1-3 km from the chemical plant) -75.2 pg TEQ/g fat, in four residents' blood samples (5-8 km from the plant) -24.5 pg TEQ/g fat. To assess cancer risk and reproductive health status, official medical statistical information was used. In general, the male cancer mortality observed rate in Chapaevsk is higher than expected. The SMR is higher for lung cancer 3.1(C.I. 2.6-3.8), urinary organs 2.6(C.I. 1.7-3.6). Chapaevsk women have a higher risk overall due to breast cancer 2.1(C.I. 1.6-2.7) and cervix cancer 1.8(C.I. 1.0-3.1). The incidence rates were higher for lung cancer in males and for female breast cancer in all age groups compared to Russia and Samara Region in 1998. Significant disruptions in reproductive function were detected. The mean frequency of spontaneous abortions in the last seven years was statistically higher 24.4% in Chapaevsk (compared to other of the towns region). The average rate of premature labor was 45.7 per 1000 women in Chapaevsk that is significantly higher than in most Samara Region towns. The frequency of newborns with low birth weight was 7.4%. In Russia and in most of the Samara Region towns, this rate is lower (6.2-5.1%) but not statistically different. For the determination of congenital morphogenetic conditions (CMGC), 369 children born between 1990 and 1995 were examined. The average number of CMGC per child was significantly higher, 4.5 for boys and 4.4 for girls. The first results indicated serious disruptions associated with high dioxin levels in human milk and blood in Chapaevsk. We suggest that Chapaevsk is an incredibly interesting site for further environmental-epidemiological research to assess the impact of dioxins on human health.     

Bioavailability of heavy metals in fresh water Tilapia nilotica (Oreachromis niloticus Linnaeus, 1758): Potential risk to fishermen and consumers

The study was undertaken to assess the accumulation of some heavy metals (Cr, Co, Cu, Ni, Zn, Pb and Cd) in different tissues (muscle, gills, heart, liver, brain, bone and skin) of Tilapia nilotica. It is one of the most edible fish species in Egypt and was collected from a commercial fish farm in order to evaluate their potential risk to fishermen and consumers. This fish farm is fed with discharged water containing agricultural, industrial, sewage and domestic wastes. The length-weight relation and condition factor calculation of Tilapia nilotica samples showed a significant linear regression (r² = 0.920) and an average condition factor of 4.1 g/cm³. This indicated that the health status for the studied fish samples was good. Metal pollution index (MPI) values for the determined heavy metals in the different tissues reflected that the muscle was the only tissue that had the lowest content. Provisional Tolerable Weekly Intake (PTWI) values for the investigated heavy metals were lower than those reported for the permissible limits. The data were evaluated by using ANOVA statistical analysis. For appraising the human health risk effects of heavy metals in fish muscle, estimated dietary intake (EDI) and hazard quotient (HQ) were determined. HQ levels indicated that Cr and Co were the only heavy metals among the determined ones that had values more than unity. Also, their relative contributions in fish consumptions were Cr> Co> Pb> Ni> Cu> Cd> Zn. The highest average HQ value of chromium determined in this study referred to the possible adverse effects of Cr on human health. Accordingly, the potential public health risks from dietary exposure to hazardous contaminants in fish species from fish farms must be continually subjected to research, regulation and debate.     

Seveso Women's Health Study: a study of the effects of 2,3,7,8-tetrachlorodibenzo-p-dioxin on reproductive health

Although reproductive effects of 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) exposure have been reported in numerous investigations of animals, studies of this association in humans are limited. In 1976, an explosion in Seveso, Italy exposed the surrounding population to among the highest levels of TCDD recorded in humans. The relatively pure exposure to TCDD and the ability to quantify individual level TCDD exposure from sera collected in 1976 for the Seveso cohort affords a unique opportunity to evaluate the potential dose-response relationship between TCDD exposure and a spectrum of reproductive endpoints. The Seveso Women's Health Study (SWHS) is the first comprehensive study of the reproductive health of a human population exposed to TCDD. The primary objectives of the study are to investigate the relationship of TCDD and the following endpoints: (1) endometriosis; (2) menstrual cycle characteristics; (3) age at menarche; (4) birth outcomes of pregnancies conceived after 1976; (5) time to conception and clinical infertility; and (6) age at menopause. Included in the SWHS cohort are women who were 0-40 yr old in 1976, who have adequate stored sera collected between 1976 and 1980, and who resided in Zones A or B at the time of the accident. All women were interviewed extensively about their reproductive and pregnancy history and had a blood draw. For an eligible subset of women, a pelvic exam and transvaginal ultrasound were conducted and a menstrual diary was completed. More than 95% of the women were located 20 yr after the accident and roughly 80% of the cohort agreed to participate. Data collection was completed in July 1998, serum TCDD analysis of samples for analysis of endometriosis as a nested case-control study was completed in October 1998, and statistical analysis of these data should be completed in early 1999. Serum samples are now being analyzed in order to relate TCDD levels with the remaining reproductive outcomes.     

Persistent organochlorines in human breast milk collected from primiparae in Dalian and Shenyang, China

The present study determined the concentrations of organochlorines (OCs) such as polychlorinated biphenyls (PCBs), dichlorodiphenyltrichloroethane and its metabolites (DDTs), hexachlorocyclohexane isomers (HCHs), chlordane compounds (CHLs), hexachlorobenzene (HCB) and tris(4-chlorophenyl)methane (TCPMe) in human breast milk collected from primiparae in Dalian and Shenyang, northeastern China during 2002. In addition, dioxins and related compounds in pooled samples of human breast milk from Dalian and Shenyang were also analyzed. OCs were detected in all the human breast milk samples analyzed in this study. The predominant contaminants in human breast milk were HCHs, DDTs and HCB, and the levels were relatively higher than those in other countries. On the other hand, concentrations of dioxins and related compounds, PCBs, and CHLs were relatively low. Concentrations of OCs in human breast milk from Dalian, which is located along the coast of Bo Hai Strait, were significantly higher than those from Shenyang, implying that the residents in Dalian might be mainly exposed to these contaminants from seafood. When the relationship between concentrations of OCs in human breast milk and age of primiparae was examined, no significant correlation was observed. This might be caused by the limited sample numbers and narrow range of mother's age and/or recent ban of DDT and HCH production and use. Significant correlation between concentrations of TCPMe and DDTs in human breast milk suggested that technical DDT might be a source of TCPMe in the Chinese population. When daily intakes of DDTs and HCHs to infants through human breast milk were estimated, human breast milk from Dalian showed significantly higher contribution than Shenyang, implying that infants in Dalian might be at higher risk by these contaminants.     

Estimation of dioxin risk to Japanese from the past to the future

The transport processes of seventeen 2,3,7,8-chlorinated congeners of polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs) from their major sources to humans were modeled to estimate the time course, from the past to the future, of the human health risk to the Japanese population. The comparison between measured and estimated values showed that the present modeling approach represented the background levels of congeners in the environment, daily intake, and body burden reasonably well, except for in the case of 2,3,7,8-TCDF. Although PCDD/Fs in herbicides have contributed greatly to the daily intake and body burden to the Japanese population in the past, the main sources of the present intake and burden of PCDD/Fs is estimated to be incinerators. The margin of exposure (MOE) for the risk of morphological reproductive alteration in female offspring exposed prenatally was calculated based on the estimated maternal body burden. The results indicated that the MOE values were in the single digits, implying that these values may not be sufficiently large to guarantee the safety of female offspring of mothers born in the 1950s, whereas the MOE values for female offspring born in and after the latter half of the 1990s may be sufficiently large to guarantee safety.     

Arsenic contamination in the freshwater fish ponds of Pearl River Delta: bioaccumulation and health risk assessment

This study investigated the extent of arsenic (As) contamination in five common species of freshwater fish (northern snakehead [Channa argus], mandrarin fish [Siniperca chuatsi], largemouth bass [Lepomis macrochirous], bighead carp [Aristichthys nobilis] and grass carp [Ctenopharyngodon idellus]) and their associated fish pond sediments collected from 18 freshwater fish ponds around the Pearl River Delta (PRD). The total As concentrations detected in fish muscle and sediment in freshwater ponds around the PRD were 0.05–3.01 mg?kg^?1 wet weight (w. wt) and 8.41–22.76 mg?kg^?1 dry weight (d. wt), respectively. In addition, the As content was positively correlated (p?<?0.05) to total organic carbon (TOC) contents in sediments. Biota sediment accumulation factor (BSAF) showed that omnivorous fish and zooplankton accumulated higher concentrations of heavy metals from the sediment than carnivorous fish. In addition, feeding habits of fish also influence As accumulation in different fish species. In this study, two typical food chains of the aquaculture ponds were selected for investigation: (1) omnivorous food chain (zooplankton, grass carp and bighead carp) and (2) predatory food chain (zooplankton, mud carp and mandarin fish). Significant linear relationships were obtained between log As and δ ¹⁵N. The slope of the regression (?0.066 and ?0.078) of the log transformed As concentrations and δ ¹⁵N values, as biomagnifications power, indicated there was no magnification or diminution of As from lower trophic levels (zooplankton) to fish in the aquaculture ponds. Consumption of largemouth bass, northern snakehead and bighead carp might impose health risks of Hong Kong residents consuming these fish to the local population, due to the fact that its cancer risk (CR) value exceeded the upper limit of the acceptable risk levels (10^?4) stipulated by the USEPA.     

Bioaccumulation and trophic transfer of dioxins in marine copepods and fish

Despite the great concerns about dioxins in the marine environments, the biokinetics and bioaccumulation of these compounds in marine organisms remains little known. Using radioactive tracers the aqueous uptake, dietary assimilation efficiency, and elimination of dioxins were measured in marine phytoplankton, copepods and seabream. The calculated uptake rate constant of dioxins decreased with increasing trophic levels, whereas the dietary assimilation efficiency (AE) was 28.5-57.6% in the copepods and 36.6-70.2% in the fish. The dietary AE was highly dependent on the food concentrations and food type. The elimination rate constant of dioxin in the copepods varied with different exposure pathways as well as food concentration and food type. Biokinetic calculation showed that dietary accumulation was the predominant pathway for dioxin accumulation in marine copepods and fish. Aqueous uptake can be an important pathway only when the bioconcentration of dioxins in the phytoplankton was low.     

Health risk assessment for consumption of fish originating from ponds near Dabaoshan mine, South China

Mining effluents are a potential source of toxic metals in the surrounding aquatic ecosystem and pose a potential health risk to humans from fish consumption. The objective of this paper is to assess the impact of the long-term Dabaoshan mining operation on heavy metal accumulation in different fish species. Heavy metal accumulation (lead (Pb), cadmium (Cd), zinc (Zn), and copper (Cu)) in four tissues (liver, muscle, intestine, and gills) of five carp species (Hypophthalmichthys molitrix, Ctenopharyngodon idellus, Megalobrama amblycephala, Aristichthys nobilis, and Carassius auratus auratus) from two fishponds exposed to effluent waters from Dabaoshan mine, South China. The bioaccumulation factor (BAF) and target hazard quotients were calculated to assess potential health risks to local residents through fish consumption. Levels of heavy metals varied depending on the analyzed tissues. C. auratus auratus accumulated the higher Pb, Cd, Zn, and Cu in the intestine compared with other fish species. Liver of all five species contained high concentrations of Pb, Cd, Zn, and Cu. The BAF for the studied metals showed a descending order of Cd?>?Zn?>?Cu?>?Pb for fishpond 1 and Zn?>?Cd?>?Cu?>?Pb for fishpond 2. Risk assessments suggested that potential human health risk may be present due to high Pb and Cd concentration in the muscle of some fish species exceeding the national and international limits, although the target hazard quotients were less than one.     

Immunologic effects of perinatal exposure to dioxins, PCBs and organochlorine pesticides in Japanese infants

Effects of perinatal exposure to dioxins, PCBs and organochlorine pesticides on lymphocyte subsets were investigated in the peripheral blood from 101 Japanese infants with approximately 10 months of age. Perinatal exposure to these organochlorine compounds were estimated by their contamination levels in the breast milk of the mothers. Lymphocyte subsets such as CD16+, HLA-DR+, CD4+, CD4+8+, CD8+, CD3+ and CD20+ cells in peripheral venous blood were assessed in a subgroup of 92 infants. Greater exposures to HCE, chlordane and dioxins were significantly associated with the increase in the percentages of CD8+ and CD3+ T lymphocytes and CD4+/CD8+ T cell ratios, respectively. In addition, higher HCH exposure was also associated with a decrease in the percentage of HLA-DR+ T lymphocytes. Furthermore effects of dioxins, DDT and PCBs on the percentage of CD16+ T lymphocyte were more pronounced by the combined exposure of dioxins and PCBs or by the combined exposure of DDT and PCBs. Effects of HCE on the percentages of CD8+ T lymphocyte were also more pronounced by the combined exposure of HCE and chlordane. In conclusion, our study suggests that greater exposures to dioxins, PCBs and organochlorine pesticides determined in this study (except dieldrin) influence the immune system of Japanese infant, although the clinical significance of these changes is uncertain.     

Rapid-behaviour responses as a reliable indicator of estrogenic chemical toxicity in zebrafish juveniles

Whereas biochemical and molecular parameters have been well recognised as important “signposts” of individual disturbance to endocrine disrupting chemical’s (EDCs) exposure, behavioural endpoints are yet greatly overlooked as a routine tool in environmental risk assessment of EDCs. However, life histories are intimately associated with numerous inter- and intra-specific interactions, which invariably depend on the performance of effective behaviours. Within fish species, one of the most important factors influencing energy turnover earlier in the development is locomotor activity. This essential trait reflects the organism’s ability to generate and coordinate the metabolic energy required for both reproductive and non-reproductive behaviours. Inappropriate movement responses due to toxic effects of contaminants may ultimately impact important ecological variables.Therefore, in the present study, the swimming bursts of zebrafish juveniles exposed for 40 d to the synthetic estrogen ethinylestradiol (EE₂), tested at environmentally relevant concentrations (nominal concentrations of 0.5, 1 and 2 ng L⁻¹), were investigated in order to address the potential of rapid-behaviour patterns as an effective response indicator of estrogenic endocrine disrupting chemical’s exposure. This synthetic estrogen was selected due to its high prevalence in aquatic ecosystems, ability to mimic natural estrogens and proven record of causing negative effects in fish reproduction. The behavioural responses were compared with established endpoints used in the screening of EE₂ effects at adulthood. Results indicate that zebrafish juveniles’ swimming activity was significantly decreased upon EE₂ exposure. Since reduced locomotion of zebrafish may impact foraging, predator avoidance, drift and transport, and even interfere with social and reproductive behaviours, a fitness decline of wild fish populations can ultimately be hypothesized. Furthermore, behavioural endpoints were found to display higher sensitivity to EE₂ than either vitellogenin gene induction or reproductive parameters determined at adulthood.Overall, the findings of this work not only demonstrate the power of high-throughput behavioural responses, able to act as sensitive early warning signals of EDC exposure, but also highlight the potential of behavioural endpoints in providing a more comprehensive and non-invasive measure of EDC’s exposure.     

Estimation of 1999-2004 dietary daily intake of PCDDs, PCDFs and dioxin-like PCBs by a total diet study in metropolitan Tokyo, Japan

A study of the dietary intake of dioxins, consisting of polychlorinated dibenzo-p-dioxins (PCDDs), polychlorinated dibenzofurans (PCDFs) and dioxin-like polychlorinated biphenyls (dioxin-like PCBs) through foods retailed in the metropolitan Tokyo area from 1999 to 2004 was carried out by the total diet-market basket method on the basis of food classification (14 groups) and the data on food consumption in the Tokyo region obtained from the Japan Nutrition Survey. The daily intake of dioxins per kg of body weight for a 50 kg average adult body was 2.18 pg TEQ/kg/day in 1999, 1.87 pg TEQ/kg/day in 2000, 1.25 pg TEQ/kg/day in 2001, 1.60 pg TEQ/kg/day in 2002 and 2003 and 1.55 pg TEQ/kg/day in 2004, respectively. These amounts were less than the tolerable daily intake (TDI) of 4 pg TEQ/kg/day for dioxins established in Japan. The dioxins taken daily through fish and shellfish (group 10) accounted for more than 50% of sum WHO-TEQs. In addition, more than 90% of the daily intake of dioxins was taken through fish and shellfish (group 10), meat and eggs (group 11), milk and dairy products (group 12). Also, this study clearly showed that the ratio of dioxin-like PCBs in the daily intake of dioxins was increasing yearly because the reduction rate of dioxin-like PCBs was lower than that of PCDDs and PCDFs in foods.     

Contamination status of persistent organochlorines in human breast milk from Japan: recent levels and temporal trend

Contamination levels of persistent organochlorines (OCs) such as polychlorinated dibenzo-p-dioxins (PCDDs), dibenzofurans (PCDFs), biphenyls (PCBs), dichlorodiphenyltrichloroethane and its metabolites (DDTs), hexachlorocyclohexane isomers (HCHs), hexachlorobenzene (HCB), and chlordane compounds (CHLs) was examined in human breast milk collected during 2001-2004 from Fukuoka prefecture in Japan. The concentrations of OCs such as dioxins and related compounds, DDTs, CHLs and HCB in human breast milk from primiparae were comparable to or slightly higher than the data obtained during 1998, indicating that the levels of these contaminants in Japanese human breast milk have not decreased since 1998 and Japanese are continuously exposed to these chemicals, presumably via fish intake. In addition, OC levels in human breast milk from primiparae were significantly higher than those from multiparae, implying elimination of OCs via lactation. Furthermore, significant positive correlations were observed between levels of OCs in human breast milk and the age of primiparae. These results indicate that the mothers with higher age may transfer higher amounts of OCs to the first infant than to the infants born afterwards through breast-feeding, and hence the first born children might be at higher risk by OCs.