Levels Of Hexachlorocyclohexanes Research Articles

Distribution and flux of organochlorine pesticides in sediment from Prydz Bay, Antarctic: Implication of sources and trends

Surface sediments were collected from Prydz Bay, Antarctica to investigate the distribution patterns, origins, annual fluxes, and trends of organochlorine pesticides (OCPs) in the marginal sea of polar areas. The concentrations of OCPs ranged from 0.80 to 7.90 ng/g dry weight, with dichlorodiphenytrichloroethanes (DDTs) as the main components. Levels of hexachlorocyclohexanes (HCHs) and DDTs in sediment from Prydz Bay were comparable to the majority of marine sediment worldwide. The distributions of OCPs were characterized by a distinct “quasi-concentric circle” pattern, which has significantly positive relationship with total organic carbon (TOC) of sediment and controlled by the local hydrodynamic conditions and sources of organic matter. Source apportionment demonstrated that HCHs and chlordanes in Prydz Bay were mainly derived from the long range atmospheric transport (LRAT) of these compounds from off regions. However, current inputs of DDT-based compounds and lindane are suggested to exist either as a result of the LART from the neighbouring countries or re-emission from melting glacier. The annual sedimentary fluxes of OCPs were 0.007 to 7.12 pg/cm2/yr, about one to three orders of magnitude lower than some data from the Arctic areas. Based on a rough calculation of r-HCH, only 0.3–1.5% of the air-seawater net deposition would be buried in sediment, implying a long active lifetime of OCPs in Antarctica. We preliminarily indicate an increase of OCP contamination in Antarctic environment afterwards when considering the possible occurrence of “fresh” sources and low proportion of sedimentary sink.

Health risk assessment of hexachlorocyclohexane in soil, water and plants in the agricultural area of Potohar region, Punjab, Pakistan

In this study analysis of soil, water and plant residue samples is presented to evaluate the contamination levels and possible health risks. Hexachlorocyclohexane (HCH) is a persistent organic pollutant used as a pesticide in agricultural sector for pest control in order to obtain higher productivity. For analysis soil, water and crop residue samples were collected from different agricultural areas of the northern Punjab region of Pakistan. The investigation of the samples shows significant levels of HCH residues in all types of samples. Gas chromatography-mass spectrometry analysis was used to assess the higher residue levels of HCH in the samples. The concentration of HCH residues detected in samples ranged from 2.43 to 8.88µg/g in soil, nd -5.87µg/l in water and nd - 4.87µg/g in plants. The presence of HCH residues in soil, water and plant samples was beyond the recommended quality guidelines. Human health risk was evaluated for cancer and non-cancer risks through dietary and non-dietary exposure routes. The hazard index was HI > 1 in children and HI < 1 in adults, while the non-dietary incremental lifetime cancer risks (ILCR) were beyond the internationally acceptable limit of 1 × 10-5. Hence, results of the present investigation concluded the presence of high levels of HCH residues in samples and pose high health risk to the inhabitants. These findings are alarming and apprise the concerned departments for the remediation of contamination and proper implementation of environmental laws in the area.

Status, Sources, and Health Risk of Hexachlorocyclohexanes in the Air of the Rural Region of Zhangzhou, Southeast China

From October 2012 to September 2013, air samples of hexachlorocyclohexanes (HCHs) were collected by polyurethane foam passive air samplers (PUF-PAS) from Caiban Village (CbV), Baihua Village (BhV), Bumeishan Village (BmsV) and Qitang Village (QtV), located in the rural region of Zhangzhou, Southeast China. The test results showed that four HCH isomers (α-, β-, γ-, δ-HCH) were ubiquitous with ∑HCHs concentrations ranging from 4.80 to 41.9pg/m3 and a mean value of 17.7pg/m3. A seasonal variation was established in the air HCH levels. The highest ∑HCHs concentration was observed in the autumn whereas the lowest was detected in the spring. The ratio α/γ-HCH, which was used to identify the contamination source, revealed that air HCHs originated mainly from historical technical HCH residues and lindane usage. The health risk of inhalation exposure to atmospheric HCHs, assessed by the inhalation dosimetry methodology, was low and considered negligible for the local residents.

Occurrence and Human Health Risk of Dichlorodiphenyltrichloroethane (DDT) and Hexachlorocyclohexane (HCH) Pesticide Residues in Commonly Consumed Vegetables in Southwestern Nigeria.

Background.Fluted pumpkin (Telfairia occidentalis) and amaranth (Amaranthus spp.) are common leafy vegetables produced and consumed in southwestern Nigeria. These vegetables attract insect pests which are controlled by pesticides that may have adverse impacts on human health.Objectives.To determine the levels of dichlorodiphenyltrichloroethane (DDT) and hexachlorocyclohexane (HCH) pesticide residues in the two vegetables and evaluate the potential health risks associated with their consumption.Methods.The pesticide residue levels were quantitatively and qualitatively determined using a gas chromatograph coupled with electron capture detector. Health risk assessment were performed using estimated average daily intake and hazard indices for two weight categories: children (16.7 kg) and adults (60 kg).Results.The results showed that delta-HCH, DDT and methoxychlor were predominantly detected in the two vegetables from both farms and markets. In amaranth, the mean concentration of methoxychlor, DDT and delta-HCH were 4.590 ± 2.774 mg/kg (dry weight (dw)), 0.757 ± 0.457 mg/kg (dw) and 0.577 ± 0.390 mg/kg (dw), respectively, while fluted pumpkin levels were 6.223 ± 2.489 mg/kg dw (methoxychlor), 0.504 ± 0.056 mg/kg dw (delta-HCH) and 0.486 ± 0.123 mg/kg dw (DDT). The levels of HCH and DDT residues were generally above the United Kingdom/European Commission maximum residue limit. The analysis of health risk estimates for non-carcinogenic risk revealed that for both vegetables, the hazard quotient for p, p′ DDT and methoxychlor was >1 for both children and adults. The health risk estimates for carcinogenic risk revealed that hazard indices values were >1 for children for both vegetables and alpha-HCH had a hazard index >1 for adults for amaranth. This means the residue exceeds acceptable standard and present potential risk to consumers of these vegetables.Conclusions.The results obtained from the present study indicate that consumption of amaranth contaminated with alpha-HCH could pose a carcinogenic risk for adult consumers. The consumption of the two vegetables could pose both non-carcinogenic and carcinogenic health risks to children and adults. Therefore, there is need for strict enforcement of regulations on pesticide usage to minimize human health risks.Competing Interests.The authors declare no competing financial interests.

Hexachlorocyclohexane exposure alters the microbiome of colostrum in Chinese breastfeeding mothers

Breast milk, especially colostrum, is not just a source of nutrients and immune factors for the newborn, but also accumulates environmental persistent pollutants and its diverse microbes affect the early colonization of the newborn's gut. Little is known about associations between environmental pollutants and the microbial composition of human colostrum. We assessed the influence of hexachlorocyclohexane (HCH), a persistent organic pollutant (POP), in colostrums on the microbial composition of human colostrum samples. HCH concentrations in 89 colostrum samples collected from a population living on the easternmost island of China were measured via gas chromatography equipped with mass spectrometer (GC-MS), HCH exposure risks for infants via dietary intake of breast milk were assessed, and for 29 colostrum samples the microbiota were profiled using 16S rRNA gene pyrosequencing to assess the association with HCH exposure levels. Our study confirmed high colostrum exposure levels of total HCHs (12.19 ± 13.68 μg L−1) in this Chinese population. We predominantly identified Proteobacteria (67.6%) and Firmicutes (25.1%) in colostrum and microbial diversity at the genus level differed between samples with different HCH levels; e.g., Pseudomonas which contains several HCH degrading strains was found in significantly higher abundance in γ-HCH rich samples. Also, microbes that were statistically significantly associated with HCH levels were also highly correlated with each other (false discovery rate (FDR)＜0.01) and clustered in network analysis. Microbial diversity is associated with HCH levels in human colostrum and these associations might be attributable to their HCH degrading ability. These finding provide first insights into the role that environmental persistent pollutants may play in the microbial composition of human colostrum and the colonization of the infant gut.

Organochlorine pesticides air monitoring near a historical lindane production site in Spain

The landfilling and dumping of persistent organic pollutants (POPs) and other persistent hazardous chemicals, such as hexachlorocyclohexane (HCH) isomers can have significantly adverse environmental consequences and cause contamination in soil, water, and atmosphere systems. Approximately 115,000 t of HCH wastes were generated by INQUINOSA Factory located in Sabiñánigo (Aragón, Spain) from 1975 to 1992, and were mainly dumped at Bailín and Sardas landfills. Under the frame of the project plan approved by the Government of Aragón, remediation and containment measures were implemented at the derelict production facility and landfill sites. To protect and assess the local environment, the concentrations of HCH isomers, pentachlorobenzene (PeCB) and hexachlorobenzene (HCB) in air were periodically monitored in the Sardas landfills and surroundings by passive sampling devices. The influence of meteorological parameters was evaluated, showing positive correlations between temperature and HCH and HCB concentrations. The highest HCH levels were detected in Sardas landfill and INQUINOSA Factory sites. PeCB values were statistically higher in Sardas landfill than in Sabiñánigo urban core, nevertheless, HCB concentrations were similar in both sampling points. Statistically positive correlations were found among HCH isomers in all sampling points, showing a major common source. The chlorobenzenes also correlated positively with each other. The α-/γ-HCH ratios were calculated (1.46 ± 1.25; mean ± S.D.), corroborating that concentrations detected were mainly originated from the historical production, storage and waste disposal of technical HCH.

Association of in utero hexachlorocyclohexane exposure with gestational age

As endocrine disrupting chemicals, hexachlorocyclohexane (HCH) isomers were reported to impair the intrauterine growth. Although the findings of HCHs with preterm birth were well established, the associations with gestational age were limited. In the present study, we examined whether exposure to HCHs would influence gestational age. The study population included 1028 pregnant women and their offspring who were born in 2014–2015 from a birth cohort in Wuhan, China. Associations of the cord serum HCH levels with gestational age were estimated using generalized linear models. We found higher HCH levels in pregnant women, who were elder, had higher body mass index (BMI) before pregnancy, received higher education, or were exposed to smoking passively. For term birth, the 3rd tertiles of α-HCH and γ-HCH were significantly associated with shorter gestational age [crude β = −1.017, confidence interval (CI): − 2.017, − 0.018 for α-HCH, crude β = −1.068, CI: − 2.067, − 0.070 for γ-HCH], and relationships were similar after adjusted by covariates. Stratified analysis showed positive associations between α-HCH and gestational age for mothers younger than 25 years old (adjusted β = 0.610, CI: 0.061, 1.158), while showing negative relationships for mothers elder than 35 years old (adjusted β = −1.365, CI: −2.414, −0.317). In summary, our results indicated cord serum levels of HCHs were associated with gestational age at birth.

Effects of a complex contaminant mixture on thyroid hormones in breeding hooded seal mothers and their pups

There is a general lack of information on the possible effects of perfluoroalkyl substances (PFASs) on thyroid hormones (THs) in wildlife species. The effects of PFASs, which are known endocrine disruptors, on the TH homeostasis in hooded seals (Cystophora cristata) have yet to be investigated. Previously, correlations were found between plasma thyroid hormone (TH) concentrations in hooded seals, and organohalogen contaminants (OHCs) and hydroxyl (OH)-metabolites. Because animals are exposed to multiple contaminants simultaneously in nature, the effects of the complex contaminant mixtures that they accumulate should be assessed. Herein, we analyse relationships between plasma concentrations of multiple contaminants including protein-associated PFASs, hydroxylated metabolites of polychlorinated biphenyls (OH-PCBs) and lipid soluble OHCs and plasma concentrations of free and total THs, i.e. triiodothyronine (FT3, TT3) and thyroxine (FT4, TT4) in hooded seal mothers and their pups. The perfluoroalkyl carboxylates (PFCAs) were the most important predictors for FT3 concentrations and TT3:FT3 ratios in the mothers. The FT3 levels decreased with increasing PFCA levels, while the TT3:FT3 ratios increased. In the pups, hexachlorocyclohexanes (HCHs) were the most important predictors for TT3:FT3 ratios, increasing with increasing HCHs levels. Additionally, perfluoroalkyl sulfonates (PFSAs) and PFCAs were important predictors for FT4:FT3 ratios in hooded seal pups, and the ratio increased with increasing concentrations. The study suggests that PFASs contribute to thyroid disruption in hooded seals exposed to complex contaminant mixtures that include chlorinated and fluorinated organic compounds.

Depth-distribution, possible sources, and toxic risk assessment of organochlorine pesticides (OCPs) in different river sediment cores affected by urbanization and reclamation in a Chinese delta

Sediment cores were collected in urban (0–50 cm), rural (0–40 cm) and reclamation-affected river (0–40 cm) environments in the Pearl River Delta. Concentrations of 16 organochlorine pesticides (OCPs) were determined in all collected samples to identify the depth-distribution, possible sources and ecotoxicological risks of OCPs in river sediments affected by urbanization and reclamation in a Chinese delta. The results showed that the top 10 cm of rural river sediments had slightly lower concentrations of the 16 OCPs compared to urban and reclamation-affected rivers, whereas the 30–40 cm sediment layers in the rural river showed higher levels of the 16 OCPs. However, higher OCPs levels were observed in the 20–30 cm sediment layers in the urban river than in the rural and reclamation-affected rivers. The principal OCPs in most deeper sediment layers were hexachlorobezene (HCB), the combination of aldrin, endrin and dieldrin (ΣDRINs) and the combination of α-HCH, β-HCH and γ-HCH (ΣHCHs). The predominant OCPs in surface sediments were HCB, ΣDRINs and the combination of p,p’-DDD, o,p’-DDT, p,p’-DDT and p,p’-DDE (ΣDDTs). Generally, OCP concentrations decreased with depth along sediment profiles at most sampling sites in the three types of rivers. The source analyses indicated that some sampling sites were still suffering from the recent use of hexachlorocyclohexanes (HCHs), dichlorodiphenyltrichloroethanes (DDTs) and aldrin. According to the soil quality thresholds of China, the levels of HCHs and DDTs at most sampling sites were below class Ⅰ criteria. Based on the sediment quality guideline quotient (SQGQ), the combined ecotoxicological risk of OCPs (γ-HCH, dieldrin, p,p'-DDD, p,p'-DDE and p,p'-DDT) in surface sediments (0–10 cm) was higher than deeper sediments, and the rural river sediments exhibited a higher combined ecotoxicological risk than the sediments in urban and reclamation-affected rivers.

Atmospheric deposition and air‐sea gas exchange fluxes of DDT and HCH in the Yangtze River Estuary, East China Sea

AbstractThe Yangtze River Estuary (YRE) is strongly influenced by the Yangtze River and lies on the pathway of the East Asian Monsoon. This study examined atmospheric deposition and air‐sea gas exchange fluxes of dichlorodiphenyltrichloroethane (DDT) and hexachlorocyclohexane (HCH) to determine whether the YRE is a sink or source of selected pesticides at the air‐water interface under the influences of river input and atmospheric transport. The air‐sea gas exchange of DDT was characterized by net volatilization with a marked difference in its fluxes between summer (140 ng/m2/d) and the other three seasons (12 ng/m2/d), possibly due to the high surface seawater temperatures and larger riverine input in summer. However, there was no obvious seasonal variation in the atmospheric HCH deposition, and the air‐sea gas exchange reached equilibrium because of low HCH levels in the air and seawater after the long‐term banning of HCH and the degradation. The gas exchange flux of HCH was comparable to the dry and wet deposition fluxes at the air‐water interface. This suggests that the influences from the Yangtze River input and East Asian continental outflow on the fate of HCH in the YRE were limited. The gas exchange flux of DDT was about fivefold higher than the total dry and wet deposition fluxes. DDT residues in agricultural soil transported by enhanced riverine runoff were responsible for sustaining such a high net volatilization in summer. Moreover, our results indicated that there were fresh sources of DDT from the local environment to sustain net volatilization throughout the year.

Reproductive and health-related hazards of Lindane exposure in Aral sea area

Background: The Aral Sea problem arises after improper regulation of the water from cross-borders river and heavy application of the pesticides over the cotton fields in the area. Objectives: This review article was designed to highlight the reproductive and health-related hazards of Lindane exposure in Aral Sea area. Methods of Literature Research: PubMed search was done for the articles that have been published from January 2007 to December 2015 using the keywords; Lindane and related health hazards in human. Five articles were found and critically analyzed to highlight the reproductive and health-related hazards of Lindane exposure in Aral Sea area. Results: Men of reproductive age were exposed to organochlorine pesticides (including Lindane), which have estrogenic and antiandrogenic activity, and this exposure may affect the male reproductive health. The human maternal and cord blood levels of hexachlorocyclohexane (HCH) isomers, dichlorodiphenyldichloroethylene, and dichlorodiphenyltrichloroethane were higher in preterm labor than full-term labor cases. Exposure of the human farmers to Lindane may be associated with long-term abnormalities that affect sensory nerves, and short-term abnormalities that affect liver, with reduced hepatic enzymes activity and reduced hepatocyte RNA synthesis. The Lindane level of 61 ± 268 pg/g lipid detected in the newborns in Turkey. Recently; Lindane has been restricted in most countries since 2009 under the Stockholm Convention on Persistent Organic Pollutants. The WHOs International Agency for Research on Cancer reported that the large epidemiological studies in the United States and Canada showed a 60% increased risk of non-Hodgkin lymphoma in agricultural workers, and pesticide applicators exposed to Lindane. Conclusion: Organochlorine pesticides, including Lindane have estrogenic and antiandrogenic activity, which may affect the male reproductive health. The human maternal and cord blood levels of HCH were higher in preterm labor than full-term labor cases. Exposure of the human farmers to Lindane may be associated with long-term abnormalities that affect sensory nerves, and short-term abnormalities that affect liver. Further future studies needed, with screening program of blood levels of Lindane in people living in Aral Sea area to confirm the Lindane health-related hazards, and the use of Lindane should be restricted in the Aral Sea area, if such relation proved.

HCHs and DDTs in Yellow River of Henan section-a typical agricultural area in China: levels, distributions and risks.

The levels, potential sources and ecological risks of hexachlorocyclohexanes (HCHs) and dichlorodiphenyltrichloroethanes (DDTs) in Yellow River of Henan section, a typical agricultural area in China, were investigated. Surface water samples and suspended particulate matters (SPMs) were collected from 23 sites during two seasons. In wet season, the residues of ∑HCHs (α-HCH, β-HCH, γ-HCH and δ-HCH) and ∑DDTs (p,p'-DDT, o,p'-DDT, p,p'-DDE, p,p'-DDD) ranged from 41.7 to 290 and 4.42 to 269ng/L in surface water, while those varied from 0.86 to 157 and 1.79 to 96.1ng/g dw in SPM, respectively. Moreover, in surface water, the levels of HCHs and DDTs in wet season were much higher than those in dry season. The reverse was true for residues of HCHs and DDTs in SPM. Compared with the large rivers in other regions, the levels of HCHs and DDTs in the studied area ranked at high levels and the residual concentrations might cause adverse biological risk, especially for ∑HCHs during wet season. Distributions of HCHs and DDTs delineated that the input of tributaries made a significant effect on the residue of HCHs and DDTs in the mainstream. ∑HCHs in surface water were consist of 26.7% α-HCH, 30.0% β-HCH, 37.9% γ-HCH and 5.45% δ-HCH and those in SPM contained 5.16% α-HCH, 22.1% β-HCH, 60.5% γ-HCH and 12.2% δ-HCH on average. Combined with ratios of α-HCH/γ-HCH in surface water (0.70) and in SPM (0.09), the results strongly indicated that lindane was recently used or discharged in the studied area. The mean percentage of DDTs' isomers were 28.7% p,p'-DDT, 29.8% o,p'-DDT, 28.1% p,p'-DDE and 13.4% p,p'-DDD in surface water, while those were 12.5% p,p'-DDT, 31.8% o,p'-DDT, 30.5% p,p'-DDE and 25.1% p,p'-DDD in SPM. The ratios of (DDE+DDD)/∑DDTs and o,p'-DDT/p,p'-DDT revealed that the DDTs in the studied area mainly derived from long-term weathering of technical DDTs residue and the input of dicofol.

Pollution of HCHs, DDTs and PCBs in tidal flat of Hangzhou Bay 2009–2013

The concentration and distribution of three persistent organic pollutants (hexachlorocyclohexanes (HCHs), dichlorodiphenyltrichloroethanes (DDTs) and polychlorinated biphenyls (PCBs)) was assessed in tidal flat sediments collected from the south bank of Hangzhou Bay, China from 2009 to 2013. Gas chromatography coupled to triple quadrupole mass spectrometry (GC-MS/MS) was used for analysis, based on United States Environmental Protection Agency methods EPA8080A, EPA8081B, and EPA3550B. The results showed that the levels of HCHs, DDTs and PCBs decreased in the order of DDTs < HCHs < PCBs, and their mass fractions ranged from 0.29–32.91, 0.09–13.19 and 0.16–4.10 μg/kg (dry mass), respectively. The levels of HCHs, DDTs and PCBs decreased slowly from 2009 to 2013, with considerably greater concentrations in winter than in spring and summer. In this study area, the concentrations of DDTs and HCHs decreased gradually towards the mouth of Hangzhou Bay, while the concentrations of PCBs were related to changes in the local economy. In addition, the sources of HCHs and DDTs were identified as atmospheric precipitation and historical residues. Finally, we predicted that PCBs pollution primarily originated from Aroclor 1254(Lot A4), which might root in the illegal demolition and stacking of abandoned paint, transformer or electronic equipment in the south bank of Hangzhou Bay.

Assessment, Composition and Possible Source of Organochlorine Pesticides in Surface Soils from Ürümqi, China

Twenty–eight surface soil samples from 5 functional zones (park, traffic roadside, business/residential area, rural area, and industrial area) of Ürümqi, China were collected and analyzed for the concentrations of 14 organochlorine pesticides (OCPs), such as 3 isomers of hexachlorocyclohexane (HCHs) (α–HCH, β–HCH, and γ–HCH), 4 dichlorodiphenyltrichloroethanes (DDTs) (p, p′–DDT and its metabolites p, p′–DDD (1,1–dichloro–2,2–bis(p–chlorophenyl)ethane) and p, p′–DDE (1,1–dichloro–2,2–bis(4–chorophenyl)ethylene), and o, p′–DDT), and methoxychlor, aiming to survey the residue levels and compositions of these 14 OCPs, to identify possible sources of the OCPs, and to assess their potential risks to human health and the environment in surface soils of Ürümqi. The concentrations ranged from non–detected to 30.86 μg kg−1 for HCHs (sum of α–, β–, and γ–HCH), from non–detected to 40.03 μg kg−1 for DDTs (sum of p, p′–DDT, p, p′–DDD, p, p′–DDE, and o, p′–DDT), and from non–detected to 11.95 μg kg−1 for methoxychlor. The total concentrations of the OCPs ranged from 16.40 to 84.86 μg kg−1, with a mean of 41.89 ± 16.25 μg kg−1. According to the measured concentrations and occurrence rates of the 14 OCPs, DDTs, HCHs, and methoxychlor were the most dominant compounds. Among the 5 functional zones, the total concentration of OCPs was in the order of rural area > traffic roadside > park > business/residential area > industrial area. The different compositions of DDTs and HCHs indicated that the residues of these compounds in most soil samples originated from historical application, besides slight recent introduction at some sampling sites. The results of Pearson correlation analysis showed that soil total organic carbon played an important role in the residue levels of HCHs, but such relationships were not found with DDTs or other OCPs. The soil quality of Ürümqi was classified as Class I based on the guidelines of the Chinese Environmental Quality Standard for Soil (GB15618–1995), indicating that the residue levels of OCPs have little risks to the environment and human health in the study area.

Remediation HCHs POPs-contaminated soil by activated persulfate technologies: Feasibility, impact of activation methods and mechanistic implications

Hexachlorocyclohexanes (HCHs) waste stockpiles are the single largest source of POPs. Sites contaminated with high levels of HCHs pose serious threats to public health and environmental safety, but there remains a lack of proper environmentally sound solution. To provide guidance on this issue, the remediation of contaminated soil with high levels of γ-HCH (∼800mg/kg) by persulfate with three commonly applied field activation methods, namely heat activation at 40°C, high pH and Fe(III)-EDTA activation, was investigated. The effects of activation method and persulfate dosage on the degradation and dechlorination of γ-HCH were studied, and degradation pathways were proposed. The results show that heat-activated persulfate is highly effective for the remediation of γ-HCH, achieving complete degradation and dechlorination of γ-HCH in 14days. Under high pH conditions, γ-HCH rapidly dehydrochlorizes into trichlorobenzenes, which are further degraded by persulfate. On the other hand, persulfate alone at 20°C and Fe(III)-EDTA activated persulfate are not effective for the degradation of γ-HCH, due to limited generation of reactive radical species resulting from the inefficient activation of persulfate, and the competition of soil organic materials and Fe(III)-EDTA with γ-HCH for reactive radicals.

Levels and distribution of organochlorine pesticides in surface sediment after flood season from the old Yellow River Estuary, China

Organochlorine pesticides (OCPs) are characterized by ubiquity, bioaccumulation and persistence in the environment and are of worldwide concern. Sixteen surface sediment samples were analyzed for hexachlorocyclohexanes (HCHs) and dichlorodiphenyltrichloroethanes (DDTs) to provide information on the levels, distribution and sources of these compounds after flood season in the old Yellow River Estuary, China. The concentrations of ΣDDT were considerably lower than those of ΣHCH. The concentrations of ΣHCH and ΣDDT in sediments after flood season were lower than those in sediments before flood season. The distribution indicated that the levels of HCHs and DDTs from sites near the beach were higher than those in the other sites. The principal component analysis suggested the usage of HCHs could serve as input sources for OCPs. The cluster analysis suggested that there were some similar migration characteristics and similar origins among these pesticides. O'p-DDT and o'p-DDT is of the greatest concern for the ecotoxicological risk.

Seasonal and diurnal variations of atmospheric PAHs and OCPs in a suburban paddy field, South China: Impacts of meteorological parameters and sources

The atmospheric contaminations of polycyclic aromatic hydrocarbons (PAHs), hexachlorocyclohexanes (HCHs), and DDTs have been extensively monitored for decades, but contaminations in agricultural paddy fields have rarely been reported. We measured the atmospheric PAH, HCH, and DDT constituents during different rice growth stages in a suburban paddy field in South China. Diurnal variations were found in the atmospheric concentrations of PAHs and HCHs, but not for DDTs. Additional nocturnal emissions and meteorological conditions, such as low nocturnal stable atmospheric boundary layers, may be mainly responsible for the higher PAH and HCH levels at night, respectively. Atmospheric concentrations of PAH, HCH, and DDT constituents varied with rice growth stage, but no regular seasonal variation was found, suggesting that rice growth has no significant influence on the atmospheric concentrations of these chemicals. A correlation analysis suggested that meteorological parameters, such as temperature, precipitation, mixing layer height, or wind speed, may directly or indirectly affect the air concentrations of PAHs, HCHs, and DDTs. Source apportionment showed that atmospheric PAHs, HCHs, and DDTs in the paddy field originated from mixed sources, and the contribution of each source varied with time. The isomer ratio of fluoranthene/(fluoranthene + pyrene) may result in an invalid diagnosis of PAHs.

Residues and potential health risks of DDTs and HCHs in commercial seafoods from two coastal cities near Yangtze River Estuary

Five species of commercial seafoods collected from the local markets in two coastal cities near Yangtze River Estuary (Ningbo and Zhoushan) in 2010 were analyzed to study the residues, potential sources, and health risks of dichlorodiphenyltrichloroethanes (DDTs) and hexachlorocyclohexanes (HCHs) in these areas. The total levels of DDTs and HCHs in the samples ranged from 1.13–20.2 ng g–1 and 1.23–3.05 ng g–1 wet weight, respectively, and were at a middle level compared with those from other marine systems. Results from one-way analysis of variance (ANOVA) indicated species-specific distributions of DDTs and HCHs in the seafoods of the studied area, which may be related to their different lipid contents and ecological characteristics. Compositional analysis suggested that historical usage dominates in this area, and fresh inputs of lindane and dicofol may also have part contributions. With respect to DDTs, it can be metabolized into both DDD and DDE simultaneously in seafoods tested. Assessment based on maximum residue levels, acceptable or tolerable daily intakes, and hazard ratios for non-carcinogens suggested no obvious adverse health effects, while the lifetime cancer risks may be increased from dietary exposure to DDTs and HCHs.

Fingerprint of persistent organic pollutants in tissues of Antarctic notothenioid fish

In the present work, persistent organic pollutants (POPs), such as polychlorinated biphenyls (PCBs), dichlorodiphenyltrichloroethane (DDT) and metabolites, polybrominated diphenyl ethers (PBDEs), and hexachlorocyclohexane (HCH) were analyzed in three Antarctic notothenioids fish species: Trematomus newnesi (TRN), Notothenia coriiceps (NOC) and Notothenia rossii (NOR). The contribution of each POP-family to the total load was as follows: ΣPCB (40%)>ΣDDT (27%)>ΣPBDEs (23%)>ΣHCH (10%). Among the 23 PCB congeners analyzed, penta-CBs homologues were the prevalent group, followed by hexa-CBs and hepta-CBs. DDT and its metabolites presented the following trend: p,p′-DDT>p,p′-DDE~p,p′-DDD. PBDE profile was dominated by BDE-47 and BDE-99 congeners, followed by BDE-100>BDE-28>BDE-154, BDE-153. Among HCHs, the γ-HCH isomer was detected in all samples, constituting 69% total HCH load, while α-HCH and β-HCH contributions were 15% and 16%, respectively.The levels of POPs reported here suggest that NOR and NOC are more susceptible to accumulate the analyzed contaminants than TRN, a species not previously analyzed for POPs.Distribution of POPs among different tissues of the three species (muscle, liver, gonads, and gills) was also investigated. Considering lipid weight, the general pattern of POPs distribution in tissues indicated that while gonads showed higher levels of PCBs, DDTs and HCH, the most significant PBDE concentrations were recorded in gills. Also, a comparative analysis of POPs concentration in fish samples from Antarctic area was included.

Organochlorines in free-range hen and duck eggs from Shanghai: occurrence and risk assessment.

As an important part of the residents' diet in China, the consumption of hen and duck eggs has been increasing rapidly in the past decades. Being rich in protein and lipid, eggs may be one of the main exposure routes for persistent organic pollutants (POPs) to human beings. In this study, four kinds of free-range hen and duck eggs were collected from two traditional egg-producing areas in Shanghai, namely Dianshan Lake Area and Jinshan Industry Zone. Organochlorine pesticides (OCPs, 18 compounds) and polychlorinated biphenyls (PCBs, 14 compounds) were analyzed with 41 egg samples. Among all OCPs, dichlorodiphenyltrichloroethanes (DDTs) were the dominant contaminant, with the concentrations ranging from 100 to 730 ng/g, lw. Unlike the 4,4'-DDE as the predominant DDTs congener in other three kinds of eggs, the duck eggs from Jinshan Industrial Zone had an abnormally high concentration of 2,4'-DDD, which may be related to ducks' feedings in the water. The levels of hexachlorocyclohexanes (HCHs) and pentachloroanisole (PCA) in eggs from different places were similar to each other, while hexchlorobenzene (HCB) for hen eggs from Dianshan Lake was much higher than other eggs. According to the results, the DDTs residues detected in this study were mainly due to the historical usage, whereas the high ratio of γ-HCH/α-HCH suggested that there might be some recent input of lindane in these two areas. For PCBs, the congener profiles varied among species. Low molecular PCBs (Tri-PCBs and Tetra-PCBs) were main congeners for duck eggs from Dianshan Lake and all hen eggs, while high molecular PCBs accounted for more than 50 % for duck eggs from Jinshan Industrial Zone, which was consistent with the water analysis results of the synchronous study from our group. This study suggests that Dianshan Lake Area may not be a good reference area for POPs monitoring in Shanghai. The estimated daily intakes of DDTs, HCHs, HCBs, and PCBs were far below the reference limits, showing no significant health risk for human consumption by eating eggs collected in this study.