Organochlorine Compounds Residues Research Articles

Physicochemical and Spatial Distributions of Trace Elements and Organochlorine Compounds in Lake Idku Water, Egypt

This study aimed to characterize the water quality of 4 sites in Lake Idku, the third largest wetland region in Egypt regarding the physicochemical indicators, the spatial distributions of certain trace elements and organochlorine compounds (OCs). Most of the tested water quality indicators were above the permissible limits of River Nile water except nitrate was lower than the permissible limits. The distribution and concentrations of Fe, Cu, Zn, Mn, Pb, and Cd significantly differed (p > 0.05) among the sampling sites, where mean concentrations of these trace elements in all the tested sites ranged from 0.0226–0.0392, 0.010–0.098, 0.3570–1.0160, 0.084–0.942, 0.015–0.024, and 0.011–0.023 mg/L, respectively. The west site of the lake contained the highest contents of the trace elements, followed by the east, north, and then south sites. Water collected from the south site had the highest concentrations of Fe and Cu, while those collected from the west site had the highest concentrations of Zn, Pb, and Cd, and samples from the east site had the highest concentrations of Mn. The concentrations of Cu, Zn, Pb, Cd, and Mn in all samples which exceeded the Egyptian regulations, except those collected from the south site which contained levels of Mn that met the regulations. Regarding the residues of OCs, the ∑OCs can be grouped in descending order as follows: north site > east site > west site > south site, with values of 5.632, 5.230, 4.731, and 4.650 µg/L, respectively. All the detected OCs were above the maximum acceptable levels as compared to WHO standards of 0.1 μg/L, except for p,p'-DDT, p,p'-DDD, and p,p'-DDE which were at lower levels. In conclusion, the water quality of Lake Idku may at risk to biota and humans, monitoring, management, and mitigation strategies are urgently required to prevent further pollution by restricting the discharge of industrial and agricultural wastewater into Lake Idku.

The level of selected organochlorine compounds residues in popular edible mushrooms from north-eastern Poland

Although DDT, γ-HCH and PCBs have been almost completely withdrawn from world production and use, they are still present in the environment. Mushrooms are eagerly collected and consumed local raw material in north-eastern part of Poland. The aim of the study was to determine the content of DDT, γ-HCH and PCB residues in popular species (Boletus badius, Boletus edulis, Cantharellus cibarius) and to estimate the human exposure of uptaking of these compounds with mushrooms. The content of γ-HCH, DDT and PCB was determined using gas chromatography. The presence of analyzed compounds was observed in all the species under study. The highest content of γ-HCH and ΣDDT was determined in C. cibarius − 7.19 and 180.37 µg/kg of lipids, respectively, whereas the highest amount of ΣPCB was observed in B. edulis − 20.89 µg/kg of lipids. The contents were low and did not pose a threat to human health.

Trophic and fitness correlates of mercury and organochlorine compound residues in egg-laying Antarctic petrels

Understanding the drivers and effects of exposure to contaminants such as mercury (Hg) and organochlorine compounds (OCs) in Antarctic wildlife is still limited. Yet, Hg and OCs have known physiological and fitness effects in animals, with consequences on their populations. Here we measured total Hg (a proxy of methyl-Hg) in blood cells and feathers, and 12 OCs (seven polychlorinated biphenyls, PCBs, and five organochlorine pesticides, OCPs) in plasma of 30 breeding female Antarctic petrels Thalassoica antarctica from one of the largest colonies in Antarctica (Svarthamaren, Dronning Maud Land). This colony is declining and there is poor documentation on the potential role played by contaminants on individual physiology and fitness. Carbon (δ13C) and nitrogen (δ15N) stable isotope values measured in the females' blood cells and feathers served as proxies of their feeding ecology during the pre-laying (austral spring) and moulting (winter) periods, respectively. We document feather Hg concentrations (mean ± SD, 2.41 ± 0.83 μg g−1 dry weight, dw) for the first time in this species. Blood cell Hg concentrations (1.38 ± 0.43 μg g−1 dw) were almost twice as high as those reported in a recent study, and increased with pre-laying trophic position (blood cell δ15N). Moulting trophic ecology did not predict blood Hg concentrations. PCB concentrations were very low (Σ7PCBs, 0.35 ± 0.31 ng g−1 wet weight, ww). Among OCPs, HCB (1.02 ± 0.36 ng g−1 ww) and p, p’-DDE (1.02 ± 1.49 ng g−1 ww) residues were comparable to those of ecologically-similar polar seabirds, while Mirex residues (0.72 ± 0.35 ng g−1 ww) were higher. PCB and OCP concentrations showed no clear relationship with pre-laying or moulting feeding ecology, indicating that other factors overcome dietary drivers. OC residues were inversely related to body condition, suggesting stronger release of OCs into the circulation of egg-laying females upon depletion of their lipid reserves. Egg volume, hatching success, chick body condition and survival were not related to maternal Hg or OC concentrations. Legacy contaminant exposure does not seem to represent a threat for the breeding fraction of this population over the short term. Yet, exposure to contaminants, especially Mirex, and other concurring environmental stressors should be monitored over the long-term in this declining population.

Occurrence of chiral organochlorine compounds in the environmental matrices from King George Island and Ardley Island, west Antarctica.

Chiral organochlorine compounds (OCs) were measured in various environmental matrices (air, soil and vegetation) from west Antarctica using high resolution gas chromatography coupled with high resolution mass spectrometry (HRGC/HRMS). They were generally detected at a global background level compared with the previous studies. α-HCH and PCB-183 was observed in all the matrices except PCB-183 in two soil samples, while PCB-95, -136, -149, -174, -176 and o,p’-DDT were detected in most air but only a few solid matrices. Enantiomeric fractions (EFs) indicated that nonracemic residues of chiral OCs occurred in all the matrices and a wide variation of the EF values was observed in the vegetation. There was significant discrepancy between the EF values of PCB-183 and the racemic values, indicating that stereoselective depletion of PCB-183 was probably associated with the water-air exchange. The EFs values of α-HCH were generally lower than the racemic values but no statistical difference was obtained in all the matrices except lichen, supporting the assumption that water-air exchange may make influence on long-range transport of α-HCH.

Organochlorine Compound Residues in Muscle of Wild Boar (Sus scrofa L.) and Red Deer (Cervus elaphus L.): Effects of Age and Sex

Twenty-six organochlorine pesticides and 7 polychlorinated biphenyls were measured in muscle of wild boar and red deer from the Czech Republic. The concentration of DDT and its metabolites was higher (p<0.01) in wild boar than in red deer, while PCBs and HCH were higher (p<0.01) in red deer than in wild boar. The concentrations of DDT and its metabolites, hexachlorobenzene and hexachlorocyclohexane isomers were higher (p<0.05) in juvenile wild boar than in adults. PCB 153 and p,p'-DDE were the most prominent pollutants in both red deer and wild boar.

Organochlorine compound residues in the eggs of broad-snouted caimans ( Caiman latirostris) and correlation with measures of reproductive performance

Organochlorine compounds (OCCs), like pesticides (OCPs) and polychlorinated biphenyls (PCBs), are persistent lipophilic chemicals classified as endocrine-disruptors. Caiman latirostris inhabits wetlands throughout north-eastern Argentina and may accumulate OCCs. The aims of this study were to determine OCC residues in the eggs of C. latirostris and to correlate OCC burden with clutch size, hatching success and hatchling survival as measures of reproductive performance. Fourteen caiman clutches were harvested from sites with different degrees of anthropogenic intervention on wetlands surrounding Paraná River tributaries. Two to four eggs by clutch were used to quantify OCCs. OCP residues were found in all clutches. The principal contributors to the OCPs burden were the DDT family (range BDL-153.0 ng g −1 lipid) and oxychlordane (range BDL-34.3 ng g −1 lipid). PCBs were present in 92.9% of the clutches (range BDL-136.6 ng g −1 lipid). Both higher concentrations and higher diversity of pesticides, including endosulfan sulfate, were found in the nests harvested close to croplands. A negative correlation was found between clutch size and ∑OCCs ( p = 0.02, Pearson r = −0.53, r 2 = 0.28), mainly due to the ∑OCPs ( p = 0.04, Pearson r = −0.54, r 2 = 0.30). Since egg OCCs concentrations predict maternal burden, present findings suggest that higher OCCs exposure could lead to smaller clutches. Although, other factors like mother age could influence clutch size. Additionally, as caimans are a long-lived and non-migratory species, the maternal OCCs burden reflects the environmental status throughout their home range; thus, caiman eggs could be useful as a biomonitor of local contamination.

Agrochemical and polychlorobyphenyl (PCB) residues in the Mekong River delta, Vietnam

An environmental survey on pesticide residues and polychlorobyphenyl compounds (PCBs), encompassing more than 70 polar and non-polar compounds quantifiable by the techniques used, was performed in the Mekong River delta based on analyses of water, sediment and bivalve mollusc samples. Few polar compounds, such as diazinon and fenotrothion, were detected in water but a high number of non-polar chlorinated compounds, such as DDT, HCH, endosulfan and PCBs, were detected in sediments and biota. The highest concentrations measured were of DDT with an average 6.3 ng g −1 dry weight (range 0.32–67 ng g −1) in sediments and 38.6 ng g −1 (range 5.5–123 ng g −1) in molluscs’ soft tissues. Amongst chlorinated compounds, DDT concentrations were followed in decreasing order by those of PCB, endosulfan, hexachlorocyclohexane and chlordane. Residues of organochlorine compounds originate from local usage of agrochemicals although with a likely contribution also of atmospheric deposition of residues (not measured) originated elsewhere. Concentrations of PCB and pesticide residues in the aquatic environment of the Mekong River delta are lower than values reported for other regions of Vietnam and Asia. Nevertheless, current concerns about the effects of chlorinated compounds on public health advise improved control of chemical residue discharges in order to abate environmental contamination.

Organochlorine Pollutants and Stable Isotopes in Resident and Migrant Passerine Birds from Northwest Michoacán, Mexico

Although concentrations of organochlorine compounds (OCs) in birds from most of the United States and Canada have decreased over the last 30 years, there is still concern that migrant birds might be exposed to elevated concentrations of OCs during migration in Latin America. The Lerma-Chapala Basin in west-central Mexico is an important migration corridor and wintering area for many species. The objectives of this study were to assess if resident and migrant birds wintering in western Michoacán, Mexico accumulated elevated concentrations of OCs during fall and spring and to determine if the stable isotopes delta(15)N, delta(13)C, and deltaD could be used to predict burdens and origins of DDE accumulation. Resident and migrant passerine insectivorous birds were collected during fall and spring (2001-2002) in northwest Michoacán, near Chapala Lake, Mexico. The carcasses were analyzed for OCs and tail feathers were analyzed for stable isotopes delta(15)N, delta(13)C, and deltaD. The OCs detected in more than 50% of the samples were: oxychlordane (79%), p,p'-DDE (100%), p,p'-DDT (57%), and total PCBs (100%). p,p'-DDE was the OC detected at the highest concentrations, whereas residues of other OCs were near or below detection limits. Overall, there were no significant differences in concentrations of OCs between seasons or between resident and migrant birds. Concentrations of DDE and oxychlordane were somewhat higher in migrant and resident birds during spring than in fall; however, concentrations were significantly different only for oxychlordane. Two resident birds collected in fall and spring had DDE residues >10 microg/g wet weight in carcass. There were no significant differences in delta(13)C and delta(15)N values among species, between seasons, or between migrant and resident birds. However, deltaD values were clearly different between species and helped differentiate migrant from resident birds. deltaD values also were negatively and significantly correlated with DDE concentrations in carcass. Birds with more depleted deltaD values in feathers tended to have higher DDE concentrations than those with less depleted deltaD values, suggesting a potential latitudinal accumulation of DDE. Overall, our results suggest that during fall and spring, there is not a significant buildup of persistent OCs in migrant and resident passerine insectivorous birds in northwest Michoacán, Mexico.

Estrogenic microenvironment generated by organochlorine residues in adipose mammary tissue modulates biomarker expression in ERα-positive breast carcinomas

IntroductionBreast cancer is the most frequent malignant disease in women. Exposure to estrogens throughout a woman's life is a risk factor for the development of breast cancer. Organochlorine compounds (OCCs), such as pesticides and polychlorinated biphenyls, are persistent lipophilic chemicals identified as endocrine disruptors, mainly with estrogenic effects. To test the hypothesis that the amount and quality of organochlorine residues in adipose tissue adjacent to breast carcinoma affect the biological behavior of the tumor, we studied biomarker expression in breast carcinoma and the OCC body burden in patients from an urban area adjacent to Paraná fluvial system, Argentina.MethodsThe studied patients were 55 women who had undergone excision biopsies of a breast lesion diagnosed as invasive breast carcinoma. Analysis of OCC residues in breast adipose tissue was conducted by electron-capture gas–liquid chromatography. Estrogen receptor alpha (ERα), progesterone receptor (PR) and proliferative activity (Ki-67) levels were measured in paraffin-embedded biopsies of breast tumors by immunohistochemistry.ResultsAll patients had high levels of organochlorine pesticides in their breast adipose tissue. The most frequently detected compounds were p,p'-dichlorodiphenyldichloroethylene, hexachlorobenzene and β-hexachlorocyclohexane. When the whole sample was analyzed, no correlation between ERα or PR expression and OCC levels were found. In the subgroup of ERα-positive breast carcinoma patients, however, there was a positive correlation between PR expression (an estrogen-induced protein) in the neoplastic cells and OCC levels in adipose tissue surrounding the tumor. More significantly, all the ERα-positive breast carcinomas from postmenopausal women exhibited high proliferation when organochlorine levels in the surrounding adipose tissue reached levels higher than 2600 ppb. No associations were found between the organochlorine body burden and any other marker of tumor aggressiveness, such as node involvement or tumor size.ConclusionThe present results support the hypothesis that organochlorine residues in adipose tissue adjacent to breast carcinoma generate an estrogenic microenvironment that may influence the biological behavior of the tumor through ERα activation and ERα-dependent proliferation. These findings may have therapeutic implications, since interference between organochlorine compounds and hormonal therapy could be expected to occur.

The fate of chiral organochlorine compounds and selected metabolites in intraperitoneally exposed arctic char (Salvelinus alpinus)

The fate of chiral organochlorine compounds (OCs) and selected metabolites in exposed Arctic char (Salvelinus alpinus) was investigated. The contaminants alpha-hexachlorocyclohexane (alpha-HCH), cis-chlordane, 13C4-heptachlor, o,p'-DDT, and the atropisomeric chlorinated biphenyls (CBs) 95, 132, 136, 149, and 174 were solved in peanut oil and injected into the peritoneal cavity. The exposed fish were sampled three times during a five-week period, and the OC residues and detected metabolites (heptachlorexo-epoxide) were quantified in muscle and liver tissues by chiral and achiral gas chromatography-mass spectrometry and gas chromatography-electron-capture detection. Peak concentrations were reached after one to two weeks, and thereafter, the levels declined. At the end of the experiment, liver concentrations had decreased 76 to 92% relative to peak concentrations, whereas muscle concentrations showed a moderate decline (5-38%), with the exception of alpha-HCH (91%). Hydrophobicity and steric hindrance were shown to influence the assimilation process, and a significant linear relationship between the product of the steric hindrance coefficients and the inverse of the octanol-water partition coefficients (Kow) versus peak concentration was found for the CBs (r2 = 0.86, p = 0.02). The assimilation of the contaminants into muscle and liver tissues generally resulted in racemic mixtures, whereas elimination was enantioselective for alpha-HCH, cis-chlordane, o,p'-DDT, CB-132, and CB-136. The chiral heptachlor metabolite 13C4-heptachlor-exo-epoxide was formed in the fish. The enantiomeric composition of the formed metabolite indicated racemic formation, whereas the elimination process appeared to be enantioselective.

Residues of Organochlorine Compounds in Human Breast Milk Collected from Beijing, People’s Republic of China

Residues of Organochlorine Compounds in Human Breast Milk Collected from Beijing, People’s Republic of China

Contamination by organochlorine compounds in sturgeons from Caspian Sea during 2001 and 2002

Organochlorine compounds (OCs) were determined in the five species of sturgeons collected from coastal waters of Caspian Sea in Kazakhstan, Azerbaijan, Turkmenistan and Iran during 2001 and 2002 to understand their status of contamination and accumulation features. Among OCs examined, concentrations of DDTs (DDT and its metabolites) were predominant in all the sturgeon samples with concentrations ranging from 73 to 31,000 ng/g on lipid weight basis, followed by PCBs, CHLs, HCHs, HCB, dieldrin, TCPMOH, and heptachlor epoxide in order. The concentrations of OCs in beluga ( Huso huso) were the highest among all the five species. When comparing residue levels among same species, OC residues were highest in sturgeons from Azerbaijan and Kazakhstan and lowest in Turkmenistan. However, the concentrations of HCHs, dieldrin, and heptachlor epoxide in sturgeons showed less geographical variability.

Accumulation of persistent organic pollutants in the food chain of lake baikal

Lake Baikal is the deepest and oldest freshwater lake in the world containing about 20% of the world's fresh water. The present state of its contamination with organic pollutants was studied during 1997–1998 by collecting samples of sediments, phytoplankton, Zooplankton, sponges, aquatic plants, algae, muscles of various fish species, eggs of various birds and blubber of seals. Samples were prepared and analysed using GC‐MS for semivolatile priority pollutants on the US EPA list, for the presence of organochlorine pesticides and for PCBs. The results showed that there was pronounced bioaccumulation of persistent organochlorine compounds along the trophic chain, leading to substantial residues of organochlorine compounds in seals (e.g. 0.87–25.3 ppm of p,p'‐DDT in blubber).

Levels of organochlorine pesticides residues in milk of urban mothers in Kenya.

Organochlorine compounds (OCPs) are toxic products capable of producing serious adverse health consequences. When used to control pests certain OCPs persist in the environment and accumulate in the fatty tissues of living organisms reaching higher levels in animals higher in the food chain. Many countries have therefore either restricted or banned the use of OCPs. DDT used to be widely used in Kenya to control pests but is now used only to control mosquito populations. The contamination of human milk by organochlorine and other related compounds is a major concern in many parts of the world. Findings are reported from a study conducted to assess the levels of OCPs in an urban area of Kenya and to compare OCP levels in human milk from a previous study in rural areas of the country. 216 milk samples were collected from mothers aged 18-30 years in hospital maternity wards or attending postnatal clinics in selected areas in Nairobi in 1991. All mothers involved in the study were nursing either their first or second child and had lived in Nairobi for at least 5 years before the date of sampling. Samples were collected from mothers who were up to 4 weeks postpartum and analyzed for the presence of OCP residues. 9 OCPs were detected with ppDDT and ppDDE being the most frequently encountered contaminants in all samples analyzed. ppDDE was detected in 99.5% and ppDDT in 78.2% of all samples. Other residues detected were dieldrin (27%) beta-HCH (18.5%) lindane (12%) and alpha-HCH (8.8%). Levels of sum DDT ranged from 0.004 to 6.321 mg/kg fat. Mothers living in Nairobi have low levels of OCPs in their breast milk compared to mothers in rural areas. The relatively lower urban levels could be attributed to the restricted use of OCPs. People need to be taught how to safely use pesticides.

Organochlorine compound residues in human milk in the United Kingdom 1989-1991

1. The concentrations of some organochlorine pesticides and polychlorobiphenyls have been determined in 193 samples of human milk collected between July 1989 and July 1991. 2. Comparison of the results with those from previous studies in 1979-80, and earlier, shows a continuing decline in residue levels except for polychlorobiphenyls. 3. The concentrations of organochlorine pesticides and polychlorobiphenyls in human milk samples from residents in the United Kingdom compare favourably with data obtained in other countries.

Residue levels of organochlorine pollutants in fish from Abu‐Quir Bay and Idku Lake, Alexandria, Egypt

Residues of organochlorine compounds (OCs) and polychlorinated biphenyls (PCBs) were analyzed by capillary gas chromatography in fish species from Abu‐Quir bay and Idku lake at Alexandria area. The values of Grand Total (GT), Goldberg Index (GI), as well as Extractable Organic Matter (EOM) are reported in this study. The results revealed an increase in chlorinated hydrocarbons with increase in body size and fat content. DDTs and PCBs were the most predominant contaminants occurring in the muscle tissue of fish samples. The concentrations of Aroclors in all samples were higher than that of other organochlorine compounds. Elevated PCBs concentrations were observed in muscle tissue of Sphyraena sphyraena and Sardina pilchardus from Abu‐Quir bay and two Tilapia sp. from Idku lake. Also, variations were found in the relative proportions of p,p'‐, and o,p‐ of DDT, DDD, DDE and DDMU in all fish samples. However, a and S‐HCH were detected in trace amount in compared with γ ‐HCH. Aroclor 1254 is the dominant compa...

Residue levels of chlorinated hydrocarbons compounds in fish from El‐Max Bay and Maryut Lake, Alexandria, Egypt

Residues of organochlorine compounds and polychlorinated biphenyls (PCBs) were analyzed by capillary gas chromatography in fish species from El‐Max Bay and Maryut Lake. The values of Grand Total (GT), and Extractable Organic Matter (EOM) were reported in this study. The results revealed an increase in chlorinated hydrocarbons with increase in body size and fat content. SDDTs and PCBs were the most predominant contaminants occurring in the muscle tissue of fish samples. Remarkable variations in the concentrations of PCBs components were noted among the species. The concentrations of Aroclors in all fish samples were higher than that of organochlorine compounds (OCs), this result indicating by reviewing to Goldberg Index (GI) a predominance of industrial activities over agricultural activities as the source of contamination of the marine environment. Elevated PCBs concentrations were observed in muscle tissue of Sphyraena Sphyraena and Sardina Pilchardus from El‐Max Bay and two Tilapia sp. from Maryut Lake....

Relationship of Diets and Environmental Contaminants in Wintering Bald Eagles

We investigated the relationship between diets and potential hazards in contaminants of wintering bald eagles (Haliaeetus leucocephalus) in the Klamath Basin of northern California and southern Oregon. We studied diets by identifying remains of 913 prey items found at perches, examining 341 castings collected from communal night roots, and observing foraging eagles. We determined residues of organochlorine compounds, lead (Pb), and mercury (Hg) in bald eagles and their prey by analyzing eagle blood samples and carcasses and 8 major prey species. Bald eagles fed largely on waterfowl by scavenging cholera-killed ducks and geese and on microtine rodents during mid- to late winter. Residues of organochlorine pesticides and Hg in prey were low, and polychlorinated biphenyls (PCB's) were detected in low concentrations in 9% of prey samples. Means Pb concentrations in prey ranged from 0.15 to 4.79 ppm. Mercury was detected in all eagle blood samples, and Pb was detected in 41% of the bald eagle blood samples. Mean Pb concentration in livers of dead eagles was 2.09 ppm and ranged as high as 27 ppm in an eagle that died of Pb poisoning. Prey of the eagles were relatively free of contaminants with the possible exception of embedded Pb shotmore » in waterfowl, which may present a potential for Pb poisoning of eagles.« less

Changes in pattern of organochlorine residues in blood of general Israeli population, 1975–1986

This study reviews data on the changes with time of the blood levels of some organochlorine compounds (OCCs) in the general Israeli population. All the studied OCC residues, except for p, p′-DDD, were significantly lower in 1985–1986 than in 1975. A decline in blood residues of organochlorine pesticides was observed mainly in the second half of the 1970s, whereas a fall in the polychlorinated biphenyl residue levels took place in the first half of the 1980s. During the latter period, unexplained increases in p, p′-DDD, dieldrin and heptachlor epoxide residue levels were seen. A significant decrease in the blood levels of OCCs quickly metabolized in the body ( p, p′-DDT, tetrachlorobiphenyls) indicated a considerable reduction of environmental exposures. The clear decline in OCC contamination of the environment and, in particular, of the human body during the reviewed period (1975–1986) resulted from the restriction imposed in Israel on the use of OCCs. Nevertheless this does not mean that this problem has been solved. Some health implications of low-level life-long OCC exposure are discussed, and further environmental and biological monitoring and control measures are recommended.

Confirmation of Residue Levels of Organochlorine Compounds in Human Milk by Gas Chromatography/Mass Spectrometry and Capillary Gas Chromatography

The residues of organochlorine compounds in yearly pooled human milk samples, which had been collected in the Tokyo Metropolitan area in 1979-1983, were evaluated by capillary gas chromatography using an electron capture detector (ECD/GC) and gas chromatography/mass spectrometry with packed columns.The concentrations of these compounds determined by selected ion monitoring (SIM) were identical to those determined by capillary ECD/GC.The concentrations on a whole milk basis (fat basis) by SIM were as follows: α-HCH, 0.10-0.31ppb (6-9ppb); β-HCH, 14.9-39.2ppb (837-1140ppb); γ-HCH, 0.10-0.16ppb (3-7ppb); o, p′-DDE, 0.06-0.11ppb (3ppb); p, p′-DDE, 18.2-56.4ppb (1020-1630ppb); o, p′-DDT, 0.11-0.41ppb (6-12ppb); p, p′-DDT, 2.22-7.86ppb (125-228ppb); p, p′-DDD, 0.03-0.10ppb (2-3ppb); HCB, 1.30-3.03ppb (73-93ppb), S-421 (a synergist for pyrethroid insecticides), 0.24-0.80ppb (10-23ppb); dieldrin, 0.36-1.55ppb (20-45ppb). However, no residues of δ-HCH and o, p′-DDD were detected (<0.01ppb on a whole milk basis). In addition, residues of chlordane-related compounds on a whole milk basis (fat basis) were determined to be as follows by SIM: oxychlordane, 0.36-0.60ppb (16-20ppb); heptachlor epoxide, 0.39-1.12ppb (22-33ppb); trans-nonachlor, 0.80-0.91ppb (24-45ppb); cis-nonachlor 0.13-0.16ppb (4-7ppb); trans-chlordane, 0.01-0.02ppb (1ppb); cis-chlordane, 0.02-0.03ppb (1ppb); compound 2 (dihydroheptachlor isomer), 0.03-0.04ppb (1-2ppb); compound 5 (chlordane isomer), 0.02-0.03ppb (1-2ppb); compound 6 (nonachlor isomer) 0.14-0.17ppb (5-8ppb).