Lung subcellular fractions and surfactant lipid metabolism of rats exposed with DDT or endosulfan intratracheally

Abstract

The effect of intracheally administered DDT (5 mg/100 g body weight) or endosulfan (1 mg/100 g body weight) for three cosecutive days have been studied on lipid metabolism of rat lung subcellular fractions. Both the insecticides did not affect the lung weight and the protein contents of microsomes, lamellar bodies and surfactant but significantly increased the phospholipid contents of microsomal and surfactant system. Most of the neutral lipid components of lung subcellular fractions were also increased by DDT or endosulfan treatments, except that of surfactant triglycerides which were decreased by DDT treatment. DDT or endosulfan both increased the incorporation of radioactive [methyl‐³H]choline into microsomal phosphatidylcholine (PC) and surfactant dipalmitoylphosphatidylcholine (DPPC) without affecting the incorporation of radioactive [methyl‐¹⁴C]methionine, showing the increased synthesis of PC via CDPcholine pathway. The results presented in this communication showed that DDT and endosulfan, the two different chloroinsecticides have similar effects on microsomal lipid metabolism but produce different biochemical manifestations on the secretion of surfactant phospholipids.     

Changes in lipid profiles of liver microsomes of rats following intratracheal administration of DDT or endosulfan

The effect of intratracheal administration of DDT (5 mg/100 g body weight) or endosulfan (1 mg/100 g body weight) to rats for three consecutive days, has been studied on liver lipid metabolism. The administration of DDT but not endosulfan significantly increased the liver weight and the microsomal protein contents. Both DDT and endosulfan treatments significantly increased the contents of microsomal phosphatidylcholine (PC), total-free- and esterified cholesterol. The distribution of unsaturated fatty acids of microsomal PC and PE was increased by DDT treatment. The intratracheal administration of DDT caused fatty infiltration of liver which was probably due to increased synthesis of triglycerides (TG). This is supported by the increased incorporation of radioactive palmitate-1-14C into microsomal TG. However, the increased incorporation of palmitate-1-14C into microsomal PC and phosphatidylethanolamine (PE) after the DDT treatment, was due to the increased transacylation reaction supported by the decreased activity of microsomal phospholipase A. The intratracheal administration of endosulfan did not have pronounced effect on liver fatty infiltration, or transacylation reaction in microsomal PC and PE. However, the results have shown that the treatments of DDT or endosulfan increased the PC contents and the incorporation of radioactive [methyl-3H]choline into PC of microsomes, resulting the increased synthesis of PC via CDPcholine pathway. Thus, the intratracheally administered DDT or endosulfan to rats showed that both the insecticides cause manifestations in the biochemistry of microsomal membrane lipids, although the effects of DDT being more pronounced. Therefore, the translocation effects of these insecticides or metabolites from lung to liver is established.     

Changes in lipid profiles of liver microsomes of rats following intratracheal administration of DDT or endosulfan

Abstract

The effect of intratracheal administration of DDT (5 mg/100 g body weight) or endosulfan (1 mg/100 g body weight) to rats for three consecutive days, has been studied on liver lipid metabolism. The administration of DDT but not endosulfan significantly increased the liver weight and the microsomal protein contents. Both DDT and endosulfan treatments significantly increased the contents of microsomal phosphatidylcholine (PC), total‐free‐ and esterified cholesterol. The distribution of unsaturated fatty acids of microsomal PC and PE was increased by DDT treatment. The intratracheal administration of DDT caused fatty infiltration of liver which was probably due to increased synthesis of triglycerides (TG). This is supported by the increased incorporation of radioactive palmitate‐l‐¹⁴C into microsomal TG. However, the increased incorporation of palmitate‐l‐¹⁴C into microsomal PC and phosphatidylethanolamine (PE) after the DDT treatment, was due to the increased transacylation reaction supported by the decreased activity of microsomal phospholipase A. The intratracheal adminstration of endosulfan did not has pronounced effect on liver fatty infiltration, or transacylation reaction in microsomal PC and PE. However, the results have shown that the treatments of DDT or endosulfan increased the PC contents and the incorporation of radioactive [methyl‐³H]choline into PC of microsomes, resulting the increased synthesis of PC via CDPcholine pathway. Thus, the intratracheally administered DDT or endosulfan to rats showed that both the insecticides cause manifestations in the biochemistry of microsomal membrane lipids, although the effects of DDT being more pronounced. Therefore, the translocation effects of these insecticides or metabolites from lung to liver is established.     

Pesticide residues in Nile tilapia (Oreochromis niloticus) and Nile perch (Lates niloticus) from Southern Lake Victoria, Tanzania

Nile tilapia (Oreochromis niloticus) and Nile perch (Lates niloticus) samples were collected from fish landing stations in nine riparian districts on the Tanzanian side of Lake Victoria and screened for residues of 64 organochlorine, organophosphorus, carbamate, and pyrethroid pesticides. The residue levels in the fish fillet were up to 0.003, 0.03 and 0.2 mg/kg fresh weight (0.7, 3.8 and 42 mg/kg lipid weight) of fenitrothion, DDT and endosulfan, respectively. Mean levels within sites were up to 0.002, 0.02 and 0.1 mg/kg fresh weight (0.5, 0.5 and 16 mg/kg lipid weight), respectively. The detection of higher levels of p,p'-DDT than the degradation products (p,p'-DDD and p,p'-DDE), and higher levels of endosulfan isomers (alpha and beta) than the sulphate, in fish samples, implied recent exposure of fish to DDT and endosulfan, respectively. Generally, most of the fish samples had residue levels above the average method detection limits (MDLs), but were within the calculated ADI.     

Induction of cytochrome P-450 and phosphatidylcholine synthesis by endosulfan in liver of rats: effect of quality of dietary proteins

Administration of endosulfan significantly increased microsomal protein, cytochrome P-450 content and the activity of aminopyrine N-demethylase. Effect of endosulfan and actinomycin D either alone or together on microsomal protein, cytochrome P-450, NADPH cytochrome c reductase, aniline hydroxylase, aminopyrine N-demethylase, phosphatidylcholine content, incorporation of 3H-choline and 14C-methionine were studied in rats given amino acid deficient and supplemented diets. Administration of endosulfan significantly increased the above parameters in both the dietary groups, whereas administration of actinomycin D did not have any effect in rats fed supplemented diets, however, significant decrease in the PC and the incorporation of choline and methionine into PC of rats fed deficient diet were observed. A positive correlation in the effect of endosulfan on hepatic mixed function oxidase activity and hepatic phosphatidylcholine is observed.     

Induction of cytochrome p‐450 and phosphatidylcholine synthesis by endosulfan in liver of rats : Effect of quality of dietary proteins

Abstract

Administration of endosulfan significantly increased microsomal protein, cytochrome P‐450 content and the activity of aminopyrine N‐demethylase. Effect of endosulfan and actinomycin D either alone or together on microsomal protein, cytochrome P‐450, NADPH cytochrome c reductase, aniline hydroxylase, aminopyrine N‐demethylase, phosphatidylcholine content, incorporation of ³H‐choline and ¹⁴C‐methionine were studied in rats given amino acid deficient and supplemented diets. Administration of endosulfan significantly increased the above parameters in both the dietary groups, whereas administration of actinomycin D did not have any effect in rats fed supplemented diets, however, significant decrease in the PC and the incorporation of choline and methionine into PC of rats fed deficient diet were observed. A positive correlation in the effect of endosulfan on hepatic mixed function oxidase activity and hepatic phosphatidylcholine is observed.     

Insecticide residues in bats along a land use-gradient dominated by cotton cultivation in northern Benin,West Africa

Many regions in Africa are currently being converted from subsistence to cash crop farming such as cotton. Agricultural intensification is usually accompanied by increased use of pesticides, which can have an impact on non-target organisms. Bats are particularly sensitive to insecticide loads while providing substantial ecosystem services as predators of herbivorous insects. In this study, pesticide residues in bats in a landscape in northern Benin were investigated, which spanned a land use gradient from an agricultural zone dominated by cotton farms, through a buffer zone, and into a national park. Insecticides used in cotton cultivation, such as endosulfan, chlorpyrifos, flubendiamide, and spirotetramat, as well as persistent insecticides such as bis(4-chlorophenyl)-1,1,1-trichloroethane (DDT), lindane, and aldrine, were analysed. Insecticide residues detected in bats comprised DDT, endosulfan, and their corresponding transformation products. Maximum concentrations in the sampled bats were 11.2 mg/kg lipid of p,p′-DDE (median: 0.0136 mg/kg lipid) and 0.797 mg/kg lipid of β-endosulfan (median: below detection limit [DL]). While insecticide concentrations were below lethal concentrations our data suggest that DDT had probably been recently used in the study region, and larger scale use would pose an increased risk for bat populations due to the high biomagnification of DDT.     

Exposure to low doses of endosulfan and chlorpyrifos modifies endogenous antioxidants in tissues of rats

Two experiments were conducted in male SD rats (225-250 g) to determine changes in the activities of endogenous antioxidants superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GPX) and concentrations of glutathione (GSH) in tissues after exposure to low doses of endosulfan and chlorpyrifos using a whole body exposure technique. In both experiments, 6 rats/group were exposed 3 hr/day, 5 days/week for 30 days to: 0 (control), 5, 10, 20, 40 and 60% of LD50 of either pesticide in 50% ethanol; actual concentrations were: endosulfan = 0, 0.5, 1.0, 2.0, 4.0, 6.0 mg/250 g body weight; chlorpyrifos = 0, 1.9, 3.8, 7.6, 15.2, and 22.8 mg/250 g body weight. Endosulfan decreased erythrocyte SOD by 21% in all groups and chlorpyrifos increased SOD by 18% in groups 40 and 60. Liver SOD was 12%-20% lower after endosulfan exposure; lung SOD was altered: endosulfan decreased activity by 21% and 51% and chlorpyrifos by 58 and 75% in the 40 and 60 groups, respectively (P < or = 0.05). Both pesticides increased plasma GPX activity at lower levels and reduced it by 26% and 19% in groups 40 and 60, respectively (P < or = 0.05). Liver GPX increased in the 60 group and lung GPX declined between 20% and 38% after endosulfan exposure. GSH in the liver and lung: endosulfan reduced GSH by about 30% at lower levels and increased by 41% or 70% at higher levels; chlorpyrifos decreased GSH by 28-40% in 20 and 60 groups, respectively (P < or = 0.05). Exposure to low, increasing levels of endosulfan and chlorpyrifos can differentially modify endogenous antioxidants SOD, GPX and GSH, which may lead to the development of oxidative stress in some tissues.     

Distribution of radiotin (Sn) in partially hepatectomised rats and its binding with subcellular components of liver cells

Distribution of radiotin (Sn¹¹³) in target organs and in the hepatic subcellular fractions was studied in sham and partially hepatectomised rats 72 hrs after the administration of tin (II) tartrate (2 mg Sn⁺⁺, 10 uCi/100 gm body weight) intraperitoneally. The results indicate that in both the groups Sn¹¹³ was maximally accumulated in liver followed by kidney and spleen. Partially hepatectomised rat however accumulated less Sn¹¹³ in liver while an increase was observed in kidney. Subcellular studies showed significantly high affinity of tin for microsomes. A compartmental shift of radiotin from cytosol to microsomal fraction was observed in hepatectomised rats when compared to sham operated rats.     

Effect of microbial activity, soil water content and added copper on the temporal distribution patterns of HCB and DDT among different soil organic matter fractions

Temporal changes in the distribution of exogenous HCB and DDT among different soil organic matter fractions were studied under sterile and non-sterile conditions, different soil water contents, and different concentrations of added Cu(2+). The residence time was 311days. Soil organic matter was fractionated into fulvic acid (FA), humic acid (HA), bound-humic acid (BHA), lipid, and insoluble residue (IR) fractions by a methyl isobutyl ketone (MIBK) method. Results revealed that there is a mass transfer tendency of DDT and HCB from FA, HA and BHA to IR and lipid fractions with increasing residence time. Microbial activity accelerated the mass transfer, while the addition of Cu(2+) slowed it down. The HCB and DDT transfer rate decreased as the soil moisture increased from 1.9% to 60%, but increased when soil moisture increased further to 90%. A two-compartment first order kinetic model was used to describe the mass transfer from FA, HA and BHA.     

The effect of copper ions on the lipid composition of subcellular membranes in Hydrilla verticillata

The paper studies changes in the content and composition of lipids in the membranes of chloroplasts, mitochondria and microsomes of the aquatic plant Hydrilla verticillata exposed to copper ions (100 μM; 1, 3, 6 and 24 h). The rate of copper accumulation and the coefficient of its extraction by the plant were also determined. The presence of copper in the incubation medium and its accumulation in the plant tissues decreased the content of photosynthetic pigments, stimulated lipid peroxidation and enhanced membrane permeability. The gradual accumulation of copper in the plant tissues was accompanied by specific changes in the composition of lipids: the content of sulfolipids (SQDG) in chloroplasts declined; the content of monogalactosyl diacylglycerols (MGDG), digalactosyl diacylglycerols (DGDG) and phosphatidyl glycerols (PG) in chloroplasts and mitochondria grew after an hour of copper exposure; and the content of all the lipids except phosphatidic acids (PA) decreased after 3 h of exposure. The decline in the content of phosphatidyl cholines (PC) was first observed in the membranes of microsomes (after an hour of exposure) and later in the membranes of chloroplasts and mitochondria (after 3-6 h of exposure). The experiments with incorporation of [2-¹⁴C]sodium acetate into fatty acids of polar lipids showed that in parallel with lipid destruction, there took place an intensive and specific renewal of the lipid pool of subcellular membrane fractions.     

A combined NMR- and HPLC-MS/MS-based metabolomics to evaluate the metabolic perturbations and subacute toxic effects of endosulfan on mice

Endosulfan is the newly persistent organic pollutants (POPs) added to the Stockholm Convention as its widespread use, persistence, bioaccumulation, long-range transport, endocrine disruption, and toxicity related to various adverse effects. In the present study, male mice were administrated endosulfan at 0, 0.5, and 3.5 mg/kg by gavage for 2 weeks. ¹H-NMR-based urinary metabolomics, HPLC-MS/MS-based targeted serum metabolomics, clinical analysis, and histopathology techniques were employed to evaluate the metabolic perturbations of subacute endosulfan exposure. Endosulfan exposures resulted in weight loss, liver inflammation and necrosis, and alterations in serum amino acids and urine metabolomics. Based on altered metabolites, several significantly perturbed pathways were identified including glycine, serine, and threonine metabolism; TCA cycle; pyruvate metabolism; glycolysis or gluconeogenesis; glycerophospholipid metabolism; and glyoxylate and dicarboxylate metabolism. Such pathways were highly related to amino acid metabolism, energy metabolism, and lipid metabolism. In addition, metabolomic results also demonstrated that gut microbiota was remarkably altered after endosulfan exposure. These observations may provide novel insight into revealing the potential toxic mechanism and evaluating the health risk of endosulfan exposure at metabolomic level.     

Temporal change in the distribution patterns of hexachlorobenzene and dichlorodiphenyltrichloroethane among various soil organic matter fractions

Residence time-dependent distribution patterns of hexachlorobenzene (HCB) and dichlorodiphenyltrichloroethane (DDT) among different soil organic matter fractions of three Chinese soils were investigated. Soil organic matter (SOM) was fractionated into fulvic acid (FA), humic acid (HA), bound-humic acid (BHA), lipid, and insoluble residue (IR) fractions using methyl isobutyl ketone (MIBK) method. Results revealed that as the residence time prolonged, the amounts of HCB and DDT in the FA, HA and BHA fractions decreased, while those in the lipid and IR fractions increased. One- and two-compartment first order, and one- and two-parameter pore-diffusion kinetic models were used to describe the mobility of HCB and DDT from the FA, HA and BHA fractions. The results suggest that excellent agreements were achieved between the experimental data and fits to the two-compartment first order kinetic model (R2>0.97). The transfer rates of HCB and DDT followed the order FA>HA>BHA.     

Polybrominated diphenyl ethers and organochlorine compound levels in brown trout (Salmo trutta) from Andean Patagonia, Argentina

Polybrominated diphenyl ethers (PBDEs), polychlorinated biphenyls (PCBs), DDTs and endosulfan residues were analyzed in muscle, liver, gonads, gills and stomach content of brown trout (Salmo trutta) from the Andean Patagonia. PBDEs, PCBs and DDTs levels were positively correlated with lipid content, while less hydrophobic endosulfans showed a poor correlation. Endosulfan levels were about 99.9% of total contaminant (highest levels in liver 500 × 10³ ng g⁻¹ lipid weight), with α-/β-isomers ratio >1 in all organs. These results are in agreement to the current-use of the technical endosulfan and also suggest acute exposure to this insecticide. Conversely, DDT/DDE ratio reflects fish exposure to old DDT sources, showing a DDE predominance. Gills had the highest levels of DDTs, PCBs and PBDEs, indicating they represent the main uptake pathway for such hydrophobic compounds from water column. PCBs showed the lowest levels in all organs and the PBDEs/PCBs ratios >1 agree with worldwide trends. PBDEs levels in gonads, gills, liver and muscle exceeded 80 ng g⁻¹ (lipid weight) and were higher than other values reported in the Southern Hemisphere. BDE-47 was the predominant congener, suggesting higher bioaccumulation potential and possible brown trout metabolism of higher congeners. Since there is no point source of PBDEs in the region and residues were dominated by lower brominated congeners, atmospheric transport could be the main source of these compounds. This first report of PBDEs levels in fish from Argentina contributes to the knowledge about environmental trends of these persistent organic pollutants (POPs) in remote areas such as the Andean Patagonia.     

Complete dechlorination of endosulfan and lindane using Mg0/Pd(+4) bimetallic system

A Mg0/Pd(+4) bimetallic system was evaluated to dechlorinate endosulfan and lindane in the aqueous phase. Studies were conducted with endosulfan and lindane separately, with or without acid in a 1:1 (v/v) water:acetone phase. In the absence of any acid, higher degradation of endosulfan and lindane was observed using Mg0/Pd(+4) doses of 10/0.5 and 4/0.1 mg/mL, respectively. Acetone plays an important role in facilitating the dechlorination reaction by increasing the solubilities of pesticides. Dechlorination kinetics for endosulfan and lindane (30 and 50 mg/L [30 and 50 ppm] concentration of each pesticide) were conducted with varying Mg0/Pd(+4) doses, and the time-course profiles were well-fitted into exponential curves. The optimum observed rate constants (k(obs)) for endosulfan and lindane were obtained with Mg0/Pd(+4) doses of 5/0.5 and 4/0.1 mg/mL, respectively. Gas chromatography-mass spectrometry analyses revealed that endosulfan and lindane were dechlorinated completely into their hydrocarbon skeletons-Bicyclo [2,2,1] hepta 2-5 diene and benzene, respectively.     

DDT uptake by arbuscular mycorrhizal alfalfa and depletion in soil as influenced by soil application of a non-ionic surfactant

A greenhouse pot experiment was conducted to investigate the colonization of alfalfa roots by the arbuscular mycorrhizal (AM) fungus Glomus etunicatum and application of the non-ionic surfactant Triton X-100 on DDT uptake by alfalfa and depletion in soil. Mycorrhizal colonization led to an increase in the accumulation of DDT in roots but a decrease in shoots. The combination of AM inoculation and Triton X-100 application enhanced DDT uptake by both the roots and shoots. Application of Triton X-100 gave much lower residual concentrations of DDT in the bulk soil than in the rhizosphere soil or in the bulk soil without Triton X-100. AM colonization significantly increased bacterial and fungal counts and dehydrogenase activity in the rhizosphere soil. The combined AM inoculation of plants and soil application of surfactant may have potential as a biotechnological approach for the decontamination of soil polluted with DDT.     

α-Amylase and α-glucosidase inhibitor effects and pancreatic response to diabetes mellitus on Wistar rats of Ephedra alata areal part decoction with immunohistochemical analyses

Ephedra alata, known as a medicinal plant in China, was used in this study as aqueous extract from aerial parts, for diabetes mellitus treatment. This study was carried out on two parts, in vitro, we tested the effect of the studied extract on the inhibition of α-glucosidase and α-amylase activities, and in vivo on Wistar male rats receiving alloxan intraperitoneally at a rate of 125 mg/kg. Extract (100, 200, and 300 mg/kg of body weight) was administrated for 28 days by oral gavage. Blood glucose, amylase, lipase, and lipid profile level were determined. Oxidative stress was evaluated by enzymatic activities of superoxide dismutase (SOD), catalase (CAT) and glutathione peroxidase (GPx), and by estimation of lipid peroxidation and protein carbonyl (PC) level. Histopathological changes in pancreas were investigated under photonic microscopy using immunohistochemical procedure. Our findings showed that aqueous extract inhibited in vitro both α-glucosidase and α-amylase activities and its use in vivo at 300 mg/kg of body weight restored pancreas weight and weight gain, ameliorated significantly (p ? 0.05) biochemical parameters; it prevented the increase in lipid and protein oxidation and the decrease in enzymatic and non-enzymatic defense system. Histological study of treated animals showed a comparable healed regeneration of beta cells.

     

Metabolism of DDT in different tissues of young rats

The bioconcentration and distribution pattern of p,p'-DDT 1,1,1-1trichloro-2,2-bis(2-chlorophenyl-4-chlorophenyl)-ethane] and its main metabolites (p,p'-DDD [1,1-dichloro-2,2-bis (4-chlorophenyl) ethane] and p,p'-DDE [1,1-dichloro-2,2-bis (4-chlorophenyl) in adipose tissue, liver, brain, kidney, thymus, and testis were examined in young rats after 10 days of intraperitoneal injection of 50 and 100 mg of p,p'-DDT/kg of body weight. Analyses were performed by high-resolution gas chromatography. p,p'-DDT was found to be accumulated in a dose-dependent manner with the highest concentration in adipose tissue. However, in brain, the accumulation of pesticide was low and remained unchanged at the higher dose. This difference may relate to the protective role of the blood-brain barrier, which limits the access of the xenobiotic in the cerebral compartment, and to the differential tissue lipid composition. Although tissues concentration of p,p'-DDE and p,p'-DDD correlated positively to total p,p'-DDT levels, the active role in detoxification of pollutants may explain why p,p'-DDD is more abundant in liver than in the rest of organs. On the contrary, in brain, the concentration of p,p'-DDE is higher than that of p,p'-DDD, suggesting that the metabolism of the parent insecticide proceeds via more than one pathway.     

Age trends and reproductive transfer of organochlorine compounds in long-finned pilot whales from the Faroe Islands

Total DDT and PCB concentrations were determined in blubber of 130 long-finned pilot whales, Globicephala melas (100 females and 30 males) from the Faroe Islands (northern north-east Atlantic). In males and immature females no relation was observed between age and organochlorine concentrations or the ratio of tDDT (total DDT)/PCB; in contrast, concentrations and ratios in mature females declined with age, which is attributed to reproductive transfer to their offspring during gestation and lactation. Relative abundance of DDE respective to tDDT increased in males and young females and decreased in mature females. Organochlorine transfer to offspring during lactation was found to represent about 60-100% of the mother's body load, while that occurring during gestation was estimated to be much lower, in the range 4-10% of mother's body load. Transfer rates tended to decrease with mother's age and were, consequently, much higher in primiparous females than in those that had already given birth. Transplacental rates were found to be consistent with the ratio between mother's body weight and neonatal body weight.     

Contents and sources of polycyclic aromatic hydrocarbons and organochlorine pesticides in vegetable soils of Guangzhou, China

We investigated contents, distribution and possible sources of PAHs and organochlorine pesticides (Ops) in 43 surface and subsurface soils around the urban Guangzhou where variable kinds of vegetables are grown. The results indicate that the contents of PAHs (16 US EPA priority PAHs) range from 42 to 3077 microg/kg and the pollution extent is classified as a moderate level in comparison with other investigations and soil quality standards. The ratios of methylphenanthrenes to phenanthrene(MP/P), anthracene to anthracene plus phenanthrene (An/178), benz[a]anthracene to benz[a]anthracene plus chrysene (BaA/228), indeno[1,2,3-cd]pyrene to indeno[1,2,3-cd]pyrene plus benzo[ghi]perylene (In/In+BP) suggest that the sources of PAHs in the soil samples are mixed with a dominant contribution from petroleum and combustion of fossil fuel. The correlation analysis shows that the PAHs contents are significantly related to total organic carbon contents (TOC) (R2=0.75) and black carbon contents (BC) (R2=0.62) in the soil samples. Dichlorodiphenyltrichloroethane and metabolites (DDTs) and hexachlorocyclohexanes and metabolites (HCHs) account largely for the contaminants of OPs. The concentrations of DDTs range from 3.58 to 831 microg/kg and the ratios for DDT/(DDD+DDE) are higher than 2 in some soil samples, suggesting that DDT contamination still exists and may be caused by its persistence in soils and/or impurity in the pesticide dicofol. The concentrations of HCHs are 0.19-42.3 microg/kg.