Total Organochlorine Pesticides Concentrations Research Articles

Uptake of organochlorine pesticides (OCPs) and polychlorinated biphenyls (PCBs) by river water fish: The case of River Chenab

Organochlorine pesticides (OCPs) and polychlorinated biphenyls (PCBs) were investigated in eleven edible fish species (5 herbivorous and 6 carnivorous) collected from the River Chenab, Pakistan, during 2007–2009. Total OCP and PCB concentrations (ngg−1 wet weight, ww) ranged between 13–107 (mean: 38) and 3.1–93.7 (mean: 20) for five herbivorous fish species and 21.6–365 (mean: 148) and 2.5–108 (mean: 30) for six carnivorous species, respectively. The trends of detected organochlorine pesticides (OCPs) in fish samples were: DDTs>PCBs>chlordanes>HCHs. The mean concentration(s) (ngg−1 ww) of OCPs were relatively higher in all fish species collected near industrial areas followed by urban and agricultural areas. Risk assessment of OCPs and PCBs indicated that fish intake may pose health risk to humans with a consumption rate of >8g/person/day. The hazardous ratios for the 50th and 95th percentile data of OCPs and PCBs in fish exceeded the value of 1, suggesting that the daily exposure to OCPs and PCBs yield a lifetime cancer risk greater than 1 in 10,000.

Organochlorine pesticides in nest substratum and infertile eggs of American crocodiles (Reptilia, Crocodylidae) in a Mexican Caribbean atoll

As top predators, crocodilians can bioaccumulate high concentrations of persistent organochlorine pesticides (OCPs) that may have adverse effects on their physiology and health. Recent and illegal uses of OCPs in Mexico could affect populations of the American crocodile (Crocodylus acutus), already threatened by other factors. We analyzed 16 OCP compounds using gas chromatography with electron capture detection in seven infertile eggs and in the substratum of nine nests of American crocodiles in Banco Chinchorro, an atoll off the Mexican coast of the Yucatan peninsula. Nest type, clutch size and distance from nests to nearest lagoon were also recorded, while total length of the females attending each nest was measured directly or estimated. Although Banco Chinchorro is isolated from the mainland and from known sources of contamination, OCP residues were detected in egg and nest substratum samples collected from the atoll. OCP concentrations in eggs (range: 0.002-4.000 ppb) and nest substrata (range: 0.01-1.82 ppb) are ten to thousands times lower compared to other studies. Total OCP concentration (sum of all OCPs) in nest substrata decreased with increasing distance from the shore, suggesting that eggs deposited farther from the shore were less exposed to OCP absorption from substratum. Total OCP concentrations in eggs were positively correlated with total length of females and thus with their age. We speculate that maternal transfer from laying females is likely the major source of contaminants in eggs. Future investigations are needed to identify the origin of contaminants in Banco Chinchorro.

POPs and their ecological risk in sewage sludge of waste water treatment plants in Beijing, China

The concentrations of three classes of persistent organic compounds (POPs) in the sewage sludge from 12 Beijing wastewater treatment plants (WWTPs) were investigated and their ecological risks were assessed. The concentrations of 15 polycyclic aromatic hydrocarbons (PAHs), 27 polychlorinated biphenyl congeners (PCBs) and 15 organochlorine pesticides (OCPs) in sewage sludge were measured using gas chromatography–tandem mass spectrometry (GC–MS/MS) technique. Total PAHs concentrations ranged from 445.1 to 3,586.4 ng g−1 dry weight (dw), and the sum of the phenanthrene (Phe), anthracene (Ant), naphthalene (Nap), fluoranthene and chrysene accounted for 69.3–97.0 % of the total PAHs. The most abundant compounds present were 2-ring and 3-ring Ant, Phe and Nap, indicating a possible petrogenic source. Total PCBs concentrations were ranged between 3.2 and 21.8 ng g−1 dw. Total OCPs concentrations ranged from 38.0 to 143.3 ng g−1 dw, and the sum of total DDT, HCB and HCHs accounted for 69.6–97.7 % of the total OCPs. The levels of PAHs, PCBs and OCPs in this study were comparable to or lower than those reported in relatively WWTPs from other regions. In addition, they were also shown to have various distribution patterns, possibly due to their different wastewater sources. The 12 WWTPs may be classified into 4 groups because of their different sources of waste water based on cluster analysis. The ecological risk assessment shows that the concentrations of Ant or Fla at two sites, p,p′-DDE and ∑DDT at 83 % of the 12 sites may cause adverse ecological effects.

Spatial and seasonal variations of pesticide contamination in agricultural soils and crops sample from an intensive horticulture area of Hohhot, North-West China

The spatial variability and temporal trend in concentrations of the organochlorine pesticides (OCPs), hexachlorocyclohexane (HCH) and dichlorodiphenyltrichloroethane (DDT), in soils and agricultural corps were investigated on an intensive horticulture area in Hohhot, North-West China, from 2008 to 2011. The most frequently found and abundant pesticides were the metabolites of DDT (p,p'-DDE, p,p'-DDT, o,p'-DDT and p,p'-DDD). Total DDT concentrations ranged from ND (not detectable) to 507.41 ng/g and were higher than the concentration of total HCHs measured for the range of 4.84-281.44 ng/g. There were significantly positive correlations between the ∑DDT and ∑HCH concentrations (r (2)>0.74) in soils, but no significant correlation was found between the concentrations of OCPs in soils and clay content while a relatively strong correlation was found between total OCP concentrations and total organic carbon (TOC). β-HCH was the main isomer of HCHs, and was detected in all samples; the maximum proportion of β-HCH compared to ∑HCHs (mean value 54%) was found, suggesting its persistence. The α/γ-HCH ratio was between 0.89 and 5.39, which signified the combined influence of technical HCHs and lindane. Low p,p'-DDE/p,p'-DDT in N1, N3 and N9 were found, reflecting the fresh input of DDTs, while the relatively high o,p'-DDT/p,p'-DDT ratios indicated the agricultural application of dicofol. Ratios of DDT/(DDE+DDD) in soils do not indicate recent inputs of DDT into Hohhot farmland soil environment. Seasonal variations of OCPs featured higher concentrations in autumn and lower concentrations in spring. This was likely associated with their temperature-driven re-volatilization and application of dicofol in late spring.

Distribution, sources, and ecological risks of organochlorine pesticides in surface sediments from the Yellow River Estuary, China

Thirty-four surface sediment samples were analyzed for organochlorine pesticides (OCPs), in order to provide information on levels, distribution and sources of these compounds in the Yellow River Estuary, China. The levels of the organochlorine pesticides in samples were detected by the technique of soxhlet extraction followed by analysis by gas chromatography (GC) coupled with a mass selective detector. Total concentrations of OCPs ranged widely from 0.06 to 53.4 ng g(-1), with a mean value of 44.84 ng g(-1), at the mid level of pesticide concentrations compared to those reported in other regions worldwide. HCHs were the predominant species in the study area. The ratios of α-HCH/γ-HCH indicated that the technical HCH contamination was mainly due to a recent input of lindane in upper reach of Yellow River Estuary. The ratios of (DDD + DDE)/DDTs and DDD/DDE suggested that DDTs in sediments came mainly from the degradation of historical DDT in the environment, and DDT could be much easier to degrade into DDD under anaerobic conditions. Principal component analysis (PCA) could conclude that most of the OCPs came from early input and historical degradation products in the study area. Based on the sediment quality guidelines, γ-HCH and p'p-DDE would be of more concern for the ecotoxicological risk in this study area.

Distribution and Sources of Polychlorinated Biphenyls (PCBs) and Organochlorine Pesticides (OCPs) in Surface Waters of Jinzhou Bay in China

Polychlorinated biphenyls (PCBs) and organochlorine pesticides (OCPs) in surface water collected from the Jinzhou Bay in North China were analyzed using gas chromatography to reveal their horizontal distribution tendencies and trace their sources. Total PCB concentrations ranged from 215.4 to 3161 ng/L. The level of PCB in the opening of the Bay was higher than the inner Bay. The predominated components were 5- and 6-chlorinated PCBs, indicating these residual PCBs derived from paint additives. Total OCP concentrations ranged from 4.165 to 136.8 ng/L, whose isomer concentrations’ ratios implied the usage of technical HCH and lindane.

Organochlorine pesticides (OCPs) in soils of the coastal areas along Sanduao Bay and Xinghua Bay, southeast China

Concentrations of organochlorine pesticides (OCPs) have been measured in 21 surface soil samples (0–20cm) collected along Sanduao Bay and Xinghua Bay, southeast China. The total concentrations of OCPs in soil samples of Sanduao Bay and Xinghua Bay range from 1.85 to 54.73ng/g (dry weight) and 4.66–38.07ng/g (dry weight), respectively. The mean concentrations of soil samples two bays were in following order: DDTs>HCHs>endosulfans>chlordanes. HCHs in the study areas may have received fresh lindane input. DDTs in 85.7% soil along Sanduao Bay and Xinghua Bay indicating a use of technical DDT in these areas for a long time. But, DDTs in some soil samples along Xinghua Bay were likely due to the historical application of technical DDT. There were weak correlations between TOC contents and residues of HCHs, DDTs, chlordane and endosulfan, indicating that TOC of soil is not the only factor enhance adsorption of these compounds.

Levels and Distribution of Organochlorine Pesticides and Polychlorinated Biphenyls in Water and Sediment from the International Anzali Wetland, North of Iran

Organochlorine pesticides (OCPs) and PCBs were determined in water and sediment from the Anzali Wetland, north of Iran. The total concentrations of OCPs were 71.75-315.16 ng/l, 1.8-12.68 ng/g dry wt in water and sediments respectively, and those of polychlorinated biphenyls (PCBs) in the two phases were: nd-141.09 ng/l and 0.39-2.64 ng/g dw, respectively. Also, the results indicated that β-HCH, DDE were the most common organochlorine pesticides contaminants. In this study, the ∑PCB/∑DDT reflect the relative importance of agricultural than industrial sources in this area. a significant difference was observed between the stations. Station number 3 showed the highest range of the pollutants studied.

Persistent organochlorine pesticide and PCB residues in surface sediments of Lake Qarun, a protected area of Egypt

Organochlorine pesticides (OCPs) and polychlorinated biphenyls (PCBs) were determined in sediment samples collected from 34 locations in Lake Qarun, Egypt to elucidate their concentrations, distribution, possible sources and potential ecological risk. A total of 25 OCPs and 29 PCBs were identified and quantified. OCPs and PCBs were found to be ubiquitous pollutants in the aquatic environment of Lake Qarun, particular near urban areas reflecting the local usage and input of these pollutants. Total concentrations of OCPs and PCBs in sediments ranged from 1.01 to 164.8ngg−1 and 1.48 to 137.2ngg−1, respectively. Among OCPs, γ-HCH, heptachlor, aldrin, endrin, p,p′-DDE, oxy-chlordane and endosulfan I and II were the most abundant compounds. The composition of PCB congeners was dominated by the tri-, tetra-, penta- and hexa-chlorinated biphenyls. The ratios of certain metabolites (isomers) to their parent compounds (mixtures) indicated there are still new inputs of lindane, endrin, heptachlor and technical endosulfan to Qarun Lake, while the ratios of (p,p′-DDE+p,p′-DDD)/∑p,p′-DDTs indicate earlier usage of DDT. Contamination levels of PCBs and HCHs can be categorized as moderate to high compared to other urbanized regions worldwide. According to established sediment quality guidelines, γ-HCH, endrin and chlordanes would be more concerned OCP species for the ecotoxicological risk in Lake Qarun.

Levels and distribution of organochlorine pesticides (OCPs) and polycyclic aromatic hydrocarbons (PAHs) in topsoils from SE Romania

The aim of this work was to determine the concentrations of organochlorine pesticides (OCPs) and polycyclic aromatic hydrocarbons (PAHs) in topsoils (n=17) at two sampling depths in Southeastern Romania, including industrial (Galati iron and steel plant) and agricultural sites in Galati and Braila counties, as well as nature reserves such as Lower Prut Meadow (Galati County) and Bugeac Lake (Constanta County), and to compare them with national guidelines and values reported for other regions. The total detectable OCP concentrations vary in the ranges 58–1662ngg−1 dry weight (dw) for 0–5cm depth and 6–12,644ngg−1 dw for 5–20cm depth. Of these, the concentrations of HCHs, DDTs, and heptachlor varied in the ranges 6–6818ngg−1, 27–5826ngg−1, and 108–873ngg−1 dw, respectively, the highest values being registered near a cultivated area, located in the proximity of Siret River and Galati town, probably due to extensive use of pesticides in the past. Chlordane was detected only at one industrial site in Galati (53ngg−1 dw), while the levels of aldrin, dieldrin, endrin and mirex were below the detection limits in all the locations and for both depths. The total PAH concentrations for 5–20cm depth range from 9ngg−1 (Lower Prut Meadow) to 25,352ngg−1 dw (cattle farm), being lower than those reported for the upper 5cm layer. The PAH distribution pattern in this study is in agreement with that previously obtained for surface soils from Lower Prut Meadow (prevalence of 3‐ring PAHs), industrial area and farmland (prevalence of 4‐ and 5‐ring PAHs), their sources being industrial activity, traffic and agricultural waste burning. Carcinogenic PAHs contribute 44.8–56.4% for 5–20cm and 43.7–55.8% for 0–5cm depth to total PAHs. In some locations the HCH, DDT and PAH amounts exceed the legal values.

Accumulation pattern of persistent organochlorine pesticides in liver tissues of various species of birds from India

As part of a large study on assessing the impact of environmental contaminants in Indian avifauna, the presence of organochlorine pesticides (OCPs) in liver tissues of 16 species of birds collected from Ahmedabad, India during 2005-2007 was quantified. The higher concentrations of total organochlorine pesticides were detected in livers of shikra Accipiter badius (3.43 ± 0.99 μg/g wet wt) and the lower levels in white ibis Pseudibis papillosa (0.02 ± 0.01 μg/g wet wt). Marked differences in the concentrations of total OCPs occurred among species (p < 0.05). Concentrations of DDT and its metabolites, hexachlorocyclohexane (HCH) and isomers, dieldrin, and heptachlor epoxide were lower than the concentrations reported for various species of birds in India. Accumulation pattern of organochlorine pesticides in birds was, in general, in the order HCH > DDT > heptachlor epoxide > dieldrin. Among various pesticides analyzed, p,p'-DDE and β-HCH contributed maximum towards the total OCPs and study indicates the continuous use of lindane and DDT for agriculture and public health purpose, respectively. Although no serious threat is posed by any of the organochlorine pesticides detected in the present study species, continued monitoring is recommended.

Occurrence and distribution of organochlorine residues in surface sediments of the Candarli Gulf (Eastern Aegean)

The residual levels of organochlorine pesticides (OCPs) and polychlorinated biphenyls (PCBs) were determined in surface sediments collected from Candarli Gulf. Total concentrations of OCPs and PCBs in sediments ranged from 10.2 to 57.3 and 2.8 to 205ngg−1dwt, respectively. DDTs in sediments were derived from the aged and weathered agricultural soils in 61% of the sampling stations while 39% of the sites originated from the recent DDT inputs. Their concentrations appeared to be relatively low by global standards and only sediments receiving the impact from the Bakircay River and petrochemical industry approached the sediment quality guidelines for PCBs and DDTs. Based on ERL/ERM guidelines, DDT and PCBs posed ecological risk to the bottom-dwelling consumers.

Musks and organochlorine pesticides in breast milk from Shanghai, China: Levels, temporal trends and exposure assessment

The concentrations of musks (polycyclic musks and nitro musks) and traditional organochlorine pesticides (OCPs), including dichlorodiphenyltrichloroethane and its metabolites (DDT, DDE, DDD, and total DDTs), hexachlorobenzene (HCB), and hexachlorocyclohexanes (HCHs) in breast milk collected in Shanghai, China during the period 2006–2010, were determined. The total concentrations ranged from 4.7 to 276.2 (median: 58.4) ng/glipid weight (lw) for musks and from 88.3 to 2532.9 (median: 1003.8)ng/glw for OCPs. 4,4′-DDE (median: 655.4ng/glw) was the predominant OCP, followed by β-HCH (median: 172.5ng/g lw), and HHCB (1,3,4,6,7,8-hexahydro-4,6,6,7,8,8-hexamethylcyclopenta[γ]-2-benzopyran) (median: 17.7ng/g lw) was the dominant musk. There was no statistical correlation between total musk concentrations, and HCB, HCHs, DDTs or total OCP concentrations, indicating their different exposure routes and metabolism in humans (p=0.182–0.325). Clear reductions in temporal trends in the levels of DDTs and HCB, especially HCHs (p<0.01) were observed during the sampling period, and the high DDE/DDT ratios in the samples indicated past exposure to DDTs. The relatively high median concentrations of HHCB and HHCB-lactone in 2010 suggested a probably increasing tendency. There were statistically significant influences regarding maternal age and parity on OCP accumulation (p=0.001–0.002), but no significant effect on musks was found (p=0.542–0.919). Musk exposure in neonates via breast milk was 2–3 orders of magnitude lower than suggested provisional tolerable daily intakes (PTDI). The estimated daily intakes for HCB and DDTs were below the PTDI in Canada, however, 56% of those for HCHs exceeded the Canadian PTDI. OCP contamination of breast milk requires further attention.

Temporal variations of organochlorine pesticides in precipitation in Beijing, China

Temporal variations of organochlorine pesticides (OCPs) were determined in precipitation and monthly depositional fluxes were calculated in Beijing from February 2009 to March 2011. Compounds which were detected most often included α-HCH and β-HCH, and the volume-weighted mean (VWM) concentration of hexachlorocyclohexanes (HCHs) was 33.0 ng L−1, accounting for 72.3% of the ∑OCPs in precipitation. The total concentrations of OCPs ranged from 3.73 to 152 ng L−1 (mean: 29.7 ± 3.5 ng L−1) for dissolved phase and from 1.61 to 114 ng L−1 (mean: 15.9 ± 2.0 ng L−1) for particulate phase, respectively. OCPs in dissolved phase dominated sampled concentrations in precipitation (HCHs: 71.8%, Chlordane: 77.7%, dichlorodiphenyltrichloroethanes-DDTs: 50.1%) with an exception of hexachlorobenzene–HCB (26.3%). Furthermore, the distribution coefficient, Kpd, was generally large in low temperature, especially in spring. The abundance of ∑OCPs in the precipitation fluctuated monthly, with high value in late winter and spring. The past farmland near the sampling site was under construction during sampling, which may be an important local re-emission source in this study. The elevated wet deposition flux of 11 selected OCPs was 14.9 μg m−2 yr−1 in Beijing.

Residues of Organochlorine Pesticides in Water and Suspended Particulate Matter from Xiangshan Bay, East China Sea

Residual levels, distribution and possible sources of organochlorine pesticides (OCPs) in nine water column and suspended particulate matter (SPM) samples collected from Xiangshan Bay, East China Sea were investigated. Total OCPs concentrations in water column and SPM ranges from 2.88 to 34.72 ng/L and 2.47 to 29.94 ng/L, respectively, which exceed the US Environmental Protection Agency regulatory limits. Moreover, low ratio of α-HCH/γ-HCH and high ratios β- and γ-HCH suggested the cocktail input pattern of fresh and weathered HCHs. Meanwhile, low ratio of (DDE + DDD)/DDT and high ratios p,p'- and o,p'-DDT reflected a "dicofol type DDT pollution" pattern.

Assessment of persistent organochlorine pollutants in sediments from Lake Manzala, Egypt

Organochlorine pesticides (OCPs) and polychlorinated biphenyls (PCBs) were determined in surface and core sediment samples collected from Manzala Lake, the largest of the Egyptian coastal lakes. Total concentrations of OCPs and ∑7 PCBs (ICES) in sediments ranged from 0.63 to 31.31ng/g and 0.26 to 31.27ng/g, respectively. Geographical distribution indicates that levels of contaminants were significantly higher in areas which are mainly influenced by municipal discharge, indicating significant sources of these compounds in urbanised areas. The composition of DDT and its metabolites suggest old input of DDT. The levels of contaminants in Manzala Lake were similar or lower than those observed in comparable areas worldwide. The profiles of ∑OCPs and ∑PCBs in a core from a site heavily impacted by sewage discharge have highest concentrations in the surface core section indicating recent inputs. Assessment of ecotoxicological risk indicated that sediments in two sites were likely to pose potential biological adverse impact.

Organochlorine Residues in Vegetables

Vegetables are important components of the human diet, and even low levels of pesticides in vegetables may have adverse effects for consumers. A study was carried out to assess residue levels of dichlorodiphenyltrichloroethane (DDT), hexachloro-cyclohexane (HCH), and endosulfan in vegetables. The total concentration of organochlorine pesticides (OCPs) ranged from 0.29 to 106.65 μg.kg−1 (wet weight). All vegetable samples had some levels of one or more organochlorine pesticide in them. Mean concentrations of ∑DDT, ∑HCH, and ∑endosulfan in vegetables were 4.20 ± 1.68, 3.12 ± 0.66, and 0.97 ± 0.21 μg.kg−1 (wet weight), respectively. The greatest OCP accumulation was in root vegetables, followed by fruit and flower and leaf vegetables. The ratio of α-HCH to γ-HCH isomers (α/γ HCH ratio) ranged from 0.03 to 3.77, which reflects the use of lindane as well as technical formulations of HCH. The ratio of (DDE + DDD)/∑DDT, and DDT/DDE were 0.55 and 1.30, respectively, indicating biotransformation and input of DDT to the environment. Vegetables had residue levels of OCPs much below recommended maximum residue limits set by the European Commission and Indian government, indicating minimal risk to the consumers.

Distribution of organochlorine pesticides (OCs) and polychlorinated biphenyls (PCBs) in marine sediments directly exposed to wastewater from Cortiou, Marseille

The future 'Calanque National Park' coastlines of the Bouches-du-Rhône and Var departments in France, constitute one of the ten biodiversity hot spots identified in the Mediterranean basin that receives industrial and urban wastewaters discharged from Marseille and its suburbs. Organochlorine pesticides (OCs) and polychlorinated biphenyls (PCBs) were measured in sediments collected from 12 sampling sites (C1-C12) of sewage discharge to the sea from the wastewater treatment plant of Cortiou-Marseille. This study aims to determine the extent of these compounds in the sediments and to establish the possible sources of these contaminants. Total pesticides in the sediments ranged from 1.2 to 190.6 ng g(-1) dry weight of sediment. The highest value was found at station C1, with a decreasing trend in total OC concentrations seaward. Among these compounds, the concentrations of the sum of dichlorodiphenyltrichloroethane (ΣDDT) were the highest, ranging from 0.7 to 114.3 ng g(-1). PCB concentrations, expressed as equivalent to Arochlor 1260, varied from 9.1 to 226.9 ng g(-1). Individually, the dominant coplanar PCB congeners CB-153, CB-138 and CB-101. Generally, PCB concentrations at stations C2, C3, C5 and C7 were higher than those at stations C10, C11 and C12. Through some pollution indices, we showed the long-term contamination input of these OCs (DDT, endosulfan, HCH and heptachlor cases) rather than a recent release resulting from degradation and long-term weathering (dieldrin, aldrin and methoxychlor cases). Occurrence of PCBs might be due to their resistance to degradation processes or/and chronic inputs. By comparison with available sediment quality guideline (SQG) values, the environmental significance and toxicological implications of PCBs and OCs (i) reveal the probable adverse effects for the sediments from C1, C5, C6, C9 and (ii) confirm the adverse effect for marine biota and more particularly for benthic communities at C2-C4, C7 and C8.

Pesticide exposure and serum organochlorine residuals among testicular cancer patients and healthy controls

The incidence of testicular cancer (TC) has been increasing worldwide during the last decades. The reasons of the increase remains unknown, but recent findings suggest that organochlorine pesticides (OPs) could influence the development of TC. A hospital-based case-control study of 50 cases and 48 controls was conducted to determine whether environmental exposure to OPs is associated with the risk of TC, and by measuring serum concentrations of OPs, including p,p’-dichlorodiphenyldichloroethylene (p,p’-DDE) isomer and hexachlorobenzene (HCB) in participants. A significant association was observed between TC and household insecticide use (odds ratio [OR] = 3.01, 95 % CI: 1.11-8.14; ORadjusted = 3.23, 95 % CI: 1.15-9.11). Crude and adjusted ORs for TC were also significantly associated with higher serum concentrations of total OPs (OR = 3.15, 95 % CI: 1.00-9.91; ORadjusted = 3.34, 95 % CI: 1.09-10.17) in cases compared with controls. These findings give additional support to the results of previous research that suggest that some environmental exposures to OPs may be implicated in the pathogenesis of TC.

The distribution of organochlorine pesticides (OCPs) in surface sediments of Bohai Sea Bay, China

The residues of organochlorine pesticides (OCPs) in 19 surface sediments of Bohai Sea Bay were determined in this study. Total OCP concentration in surface sediment ranged from 9.01 to 18.04 ng/g dry weight, with a mean concentration of 12.50 ng/g. These findings are in the mid-range of pesticide concentrations compared to those reported in other regions worldwide. DDTs and HCHs were the predominant species. The α-HCH/β-HCH ratios and the predominant γ-HCH indicate that the technical HCH contamination was due mainly to historical usage, although there appeared to be a fresh input of lindane. The results from (DDD + DDE)/ΣDDTs and DDD/DDE calculations suggest that the usage of DDT in agricultural activities was not terminated, and the historical/fresh inputs of DDT in these areas could be more easily degraded into DDD under an anoxic condition. PCA implies that the recent usage of DDT could serve as important fresh input sources for OCPs.