Effects of transplacental exposure to environmental pollutants on birth outcomes in a multiethnic population

Inner-city, minority populations are high-risk groups for adverse birth outcomes and also are more likely to be exposed to environmental contaminants, including environmental tobacco smoke (ETS), polycyclic aromatic hydrocarbons (PAHs), and pesticides. In a sample of 263 nonsmoking African-American and Dominican women, we evaluated the effects on birth outcomes of prenatal exposure to airborne PAHs monitored during pregnancy by personal air sampling, along with ETS estimated by plasma cotinine, and an organophosphate pesticide (OP) estimated by plasma chlorpyrifos (CPF). Plasma CPF was used as a covariate because it was the most often detected in plasma and was highly correlated with other pesticides frequently detected in plasma. Among African Americans, high prenatal exposure to PAHs was associated with lower birth weight (p = 0.003) and smaller head circumference (p = 0.01) after adjusting for potential confounders. CPF was associated with decreased birth weight and birth length overall (p = 0.01 and p = 0.003, respectively) and with lower birth weight among African Americans (p = 0.04) and reduced birth length in Dominicans (p < 0.001), and was therefore included as a covariate in the model with PAH. After controlling for CPF, relationships between PAHs and birth outcomes were essentially unchanged. In this analysis, PAHs and CPF appear to be significant independent determinants of birth outcomes. Further analyses of pesticides will be carried out. Possible explanations of the failure to find a significant effect of PAHs in the Hispanic subsample are discussed. This study provides evidence that environmental pollutants at levels currently encountered in New York City adversely affect fetal development.

Association between maternal serum concentration of the DDT metabolite DDE and preterm and small-for-gestational-age babies at birth

BACKGROUND

DDT (1,1,1-trichloro-2,2-bis(p-chlorophenyl)ethane) is highly effective against most malaria-transmitting mosquitoes and is being widely used in malaria-endemic areas. The metabolite, DDE (1,1-dichloro-2,2-bis(p-chlorophenyl)ethylene), has been linked to preterm birth in small studies, but these findings are inconclusive. Our aim was to investigate the association between DDE exposure and preterm birth.

METHODS

Our study was based on the US Collaborative Perinatal Project (CPP). From this study we selected a subset of more than 44000 eligible children born between 1959 and 1966 and measured the DDE concentration in their mothers' serum samples stored during pregnancy. Complete data were available for 2380 children, of whom 361 were born preterm and 221 were small-for-gestational age.

FINDINGS

The median maternal DDE concentration was 25 mg/L (range 3-178)-several fold higher than current US concentrations. The adjusted odds ratios (OR) of preterm birth increased steadily with increasing concentrations of serum DDE (ORs=1, 1.5, 1.6, 2.5, 3.1; trend p<0.0001). Adjusted odds of small-for-gestational-age also increased, but less consistently (ORs=1, 1.9, 1.7, 1.6, 2.6; trend p=0.04). After excluding preterm births, the association of DDE with small-for-gestational-age remained.

INTERPRETATION

The findings strongly suggest that DDT use increases preterm births, which is a major contributor to infant mortality. If this association is causal, it should be included in any assessment of the costs and benefits of vector control with DDT.

Breast cancer and serum organochlorines: a prospective study among white, black, and Asian women

BACKGROUND

Five small case-control studies have examined the relationship between exposure to organochlorines and the risk of breast cancer and have found inconsistent results. In these studies, organochlorine levels in breast cancer patients were measured after (or at most 6 months before) diagnosis.

PURPOSE

We tested the hypothesis that organochlorines are a risk factor for breast cancer, using prospectively gathered data on serum levels of DDE [1,1-dichloro-2,2-bis(p-chlorophenyl)ethylene] (the main metabolite of the pesticide DDT [2,2-bis(p-chlorophenyl)-1,1,1-trichloroethane]) and polychlorinated biphenyls (PCBs).

METHODS

Study subjects belonged to a cohort of 57,040 women (46,629 white, 8123 black, and 2288 Asian) from the San Francisco Bay Area who took a multiphasic health examination, independent of concern about risk of breast cancer, in the late 1960s. At that time, a sample of blood was obtained, then frozen and stored. Follow-up was through December 31, 1990. We conducted a nested case-control study of 150 case patients and 150 matched control subjects. A random sample of 50 women per racial/ethnic group who had been diagnosed with breast cancer more than 6 months after the multiphasic examination (mean follow-up = 14.2 years) was selected, and each case patient was matched to a cancer-free control subject.

RESULTS

Matched analyses found no differences in the case patients' and control subjects' serum levels of DDE (mean difference = 0.2 parts per billion [ppb]; 95% confidence interval [CI] = -6.7, 7.2) or PCBs (mean difference = -0.4 ppb; 95% CI = -0.8, 0.1). DDE levels, however, tended to be higher among black case patients compared with black controls (mean difference = 5.7 ppb; 95% CI = -3.3, 14.8), and PCBs were lower among white case patients compared with white controls (mean difference = -0.6 ppb; 95% CI = -1.2, -0.1). Organochlorine levels were significantly higher among black and Asian women compared with white women. The mean difference for DDE was 11.0 ppb for black women (95% CI = 4.3, 17.6) and 12.6 ppb for Asian women (95% CI = 6.0, 19.2); for PCBs, the respective differences were 0.8 ppb for black women (95% CI = 0.2, 1.4) and 1.4 ppb for Asian women (95% CI = 0.8, 1.9). The results were not altered by adjusting for relevant confounders, and the lack of association between exposure to organochlorines and breast cancer was present regardless of length of follow-up, year of diagnosis, or the case patient's menopausal and estrogen-receptor status.

CONCLUSION

The data do not support the hypothesis that exposure to DDE and PCBs increases risk of breast cancer.

IMPLICATIONS

Future investigations must consider the biologic mechanisms involved and variations in exposure to chemical pollutants and of breast cancer incidence rates among diverse groups of women.

In utero pesticide exposure, maternal paraoxonase activity, and head circumference

Although the use of pesticides in inner-city homes of the United States is of considerable magnitude, little is known about the potentially adverse health effects of such exposure. Recent animal data suggest that exposure to pesticides during pregnancy and early life may impair growth and neurodevelopment in the offspring. To investigate the relationship among prenatal pesticide exposure, paraoxonase (PON1) polymorphisms and enzyme activity, and infant growth and neurodevelopment, we are conducting a prospective, multiethnic cohort study of mothers and infants delivered at Mount Sinai Hospital in New York City. In this report we evaluate the effects of pesticide exposure on birth weight, length, head circumference, and gestational age among 404 births between May 1998 and May 2002. Pesticide exposure was assessed by a prenatal questionnaire administered to the mothers during the early third trimester as well as by analysis of maternal urinary pentachlorophenol levels and maternal metabolites of chlorpyrifos and pyrethroids. Neither the questionnaire data nor the pesticide metabolite levels were associated with any of the fetal growth indices or gestational age. However, when the level of maternal PON1 activity was taken into account, maternal levels of chlorpyrifos above the limit of detection coupled with low maternal PON1 activity were associated with a significant but small reduction in head circumference. In addition, maternal PON1 levels alone, but not PON1 genetic polymorphisms, were associated with reduced head size. Because small head size has been found to be predictive of subsequent cognitive ability, these data suggest that chlorpyrifos may have a detrimental effect on fetal neurodevelopment among mothers who exhibit low PON1 activity.

Differences between organophosphorus insecticides in human self-poisoning: a prospective cohort study

BACKGROUND

Although more than 100 organophosphorus insecticides exist, organophosphorus poisoning is usually regarded as a single entity, distinguished only by the compound's lethal dose in animals. We aimed to determine whether the three most common organophosphorus insecticides used for self-poisoning in Sri Lanka differ in the clinical features and severity of poisoning they cause.

METHODS

We prospectively studied 802 patients with chlorpyrifos, dimethoate, or fenthion self-poisoning admitted to three hospitals. Blood cholinesterase activity and insecticide concentration were measured to determine the compound and the patients' response to insecticide and therapy. We recorded clinical outcomes for each patient.

FINDINGS

Compared with chlorpyrifos (35 of 439, 8.0%), the proportion dying was significantly higher with dimethoate (61 of 264, 23.1%, odds ratio [OR] 3.5, 95% CI 2.2-5.4) or fenthion (16 of 99, 16.2%, OR 2.2, 1.2-4.2), as was the proportion requiring endotracheal intubation (66 of 439 for chlorpyrifos, 15.0%; 93 of 264 for dimethoate, 35.2%, OR 3.1, 2.1-4.4; 31 of 99 for fenthion, 31.3%, 2.6, 1.6-4.2). Dimethoate-poisoned patients died sooner than those ingesting other pesticides and often from hypotensive shock. Fenthion poisoning initially caused few symptoms but many patients subsequently required intubation. Acetylcholinesterase inhibited by fenthion or dimethoate responded poorly to pralidoxime treatment compared with chlorpyrifos-inhibited acetylcholinesterase.

INTERPRETATION

Organophosphorus insecticide poisoning is not a single entity, with substantial variability in clinical course, response to oximes, and outcome. Animal toxicity does not predict human toxicity since, although chlorpyrifos is generally the most toxic in rats, it is least toxic in people. Each organophosphorus insecticide should be considered as an individual poison and, consequently, patients might benefit from management protocols developed for particular organophosphorus insecticides.

German Environmental Survey 1998 (GerES III): environmental pollutants in blood of the German population

The German Environmental Survey was conducted for the third time in 1998 (GerES III). The probability sample of about 4800 subjects was selected to be representative for the German population with regard to region (East-/West-Germany), community size, age (18 to 69 years) and gender. Blood samples were taken from each study participant and questionnaires were used to get exposure-related information. Cadmium, lead, mercury, hexachlorobenzene (HCB), hexachlorocyclohexane (alpha-HCH, beta-HCH, gamma-HCH), 1,1-dichloro-2,2-bis(p-chlorophenyl)ethylene (p, p'-DDE) and polychlorinated biphenyls (PCB-138, PCB-153, PCB-180) were analysed in whole blood to document the extent, distribution, and determinants of exposure of the general population to these substances. The geometric means of Cd, Pb, and Hg in blood amounted to 0.44, 31, and 0.58 microgram/l, respectively. Smokers showed a Cadmium level of 1.1 micrograms/l and non-smokers a level of 0.28 microgram/l. The geometric mean of lead was higher in the blood of males than of females (36 micrograms/l vs. 26 micrograms/l). The concentration of mercury in blood depends on fish consumption and the number of teeth with amalgam fillings. The mean concentrations of HCB and p, p'-DDE in blood were 0.44 microgram/l and 1.6 micrograms/l, respectively. In East-Germany (the former GDR) the DDE concentration in blood was more than twice as high as in West-Germany. Geometric means for PCB were 0.42, 0.68 and 0.44 microgram/l for PCB-138, PCB-153, and PCB-180, respectively. A marked increase of HCB, DDE and PCB levels with age could be observed. alpha-HCH and gamma-HCH could be detected in 1.7% and 5.2% of the samples only. beta-HCH was quantified in 34% of the samples with a 95th percentile of 0.5 microgram/l.

Organochlorine exposure and risk of breast cancer

BACKGROUND

Some organochlorine compounds may have weak oestrogenic effects and are, therefore, suspected of increasing the risk of breast cancer. We assessed prospectively the risk of breast cancer in relation to serum concentrations of several organochlorine compounds.

METHODS

In 1976, serum samples from 7712 women were obtained from participants in the Copenhagen City Heart Study as part of physical examinations and interviews about lifestyle factors. During 17 years of follow-up, 268 women developed invasive breast cancer. Each woman with breast cancer was matched with two breast-cancer-free women from the remaining cohort. We analysed in 1996-97 the serum samples from 240 women with breast cancer and 477 controls.

FINDINGS

Dieldrin was associated with a significantly increased dose-related risk of breast cancer (adjusted odds ratio 2.05 [95% CI 1.17-3.57], p for trend 0.01). Beta-hexachlorocyclohexane increased risk slightly but not significantly (p for trend 0.24). There was no overall association between risk of breast cancer and p,p'-dichlorodiphenyltrichloroethane or metabolites or for polychlorinated biphenyls. Exclusion of women with breast cancer diagnosed within 5 years of blood sampling strengthened the result for dieldrin, but did not affect the other results.

INTERPRETATION

These findings support the hypothesis that exposure to xeno-oestrogens may increase the risk of breast cancer.

A Physiologically based pharmacokinetic and pharmacodynamic (PBPK/PD) model for the organophosphate insecticide chlorpyrifos in rats and humans

A PBPK/PD model was developed for the organophosphate insecticide chlorpyrifos (CPF) (O,O-diethyl-O-[3,5,6-trichloro-2-pyridyl]-phosphorothioate), and the major metabolites CPF-oxon and 3,5,6-trichloro-2-pyridinol (TCP) in rats and humans. This model integrates target tissue dosimetry and dynamic response (i.e., esterase inhibition) describing uptake, metabolism, and disposition of CPF, CPF-oxon, and TCP and the associated cholinesterase (ChE) inhibition kinetics in blood and tissues following acute and chronic oral and dermal exposure. To facilitate model development, single oral-dose pharmacokinetic studies were conducted in rats (0.5-100 mg/kg) and humans (0.5-2 mg/kg), and the kinetics of CPF, CPF-oxon, and TCP were determined, as well as the extent of blood (plasma/RBC) and brain (rats only) ChE inhibition. In blood, the concentration of analytes followed the order TCP >> CPF >> CPF-oxon; in humans CPF-oxon was not quantifiable. Simulations were compared against experimental data and previously published studies in rats and humans. The model was utilized to quantitatively compare dosimetry and dynamic response between rats and humans over a range of CPF doses. The time course of CPF and TCP in both species was linear over the dose range evaluated, and the model reasonably simulated the dose-dependent inhibition of plasma ChE, RBC acetylcholinesterase (AChE), and brain (rat only) AChE. Model simulations suggest that rats exhibit greater metabolism of CPF to CPF-oxon than humans do, and that the depletion of nontarget B-esterase is associated with a nonlinear, dose-dependent increase in CPF-oxon blood and brain concentration. This CPF PBPK/PD model quantitatively estimates target tissue dosimetry and AChE inhibition and is a strong framework for further organophosphate (OP) model development and for refining a biologically based risk assessment for exposure to CPF under a variety of scenarios.

Plasma organochlorine levels and the risk of breast cancer

BACKGROUND

Exposure to "environmental estrogens" such as organochlorines in pesticides and industrial chemicals has been proposed as a cause of increasing rates of breast cancer. Several studies have reported higher blood levels of 1,1-dichloro-2,2-bis(p-chlorophenyl)ethylene (DDE) and polychlorinated biphenyls (PCBs) in patients with breast cancer than in controls.

METHODS

We measured plasma levels of DDE and PCBs prospectively among 240 women who gave a blood sample in 1989 or 1990 and who were subsequently given a diagnosis of breast cancer before June 1, 1992. We compared these levels with those measured in matched control women in whom breast cancer did not develop. Data on DDE were available for 236 pairs, and data on PCBs were available for 230 pairs.

RESULTS

The median level of DDE was lower among case patients than among controls (4.71 vs. 5.35 parts per billion, P=0.14), as was the median level of PCBs (4.49 vs. 4.68 parts per billion, P=0.72). The multivariate relative risk of breast cancer for women in the highest quintile of exposure as compared with women in the lowest quintile was 0.72 for DDE (95 percent confidence interval, 0.37 to 1.40) and 0.66 for PCBs (95 percent confidence interval, 0.32 to 1.37). Exposure to high levels of both DDE and PCBs was associated with a nonsignificantly lower risk of breast cancer (relative risk for women in the highest quintiles of both DDE and PCBs as compared with women in the lowest, 0.43; 95 percent confidence interval, 0.13 to 1.44).

CONCLUSIONS

Our data do not support the hypothesis that exposure to DDT and PCBs increases the risk of breast cancer.

In utero exposure to dichlorodiphenyltrichloroethane (DDT) and dichlorodiphenyldichloroethylene (DDE) and neurodevelopment among young Mexican American children

OBJECTIVE

We investigated the relationship between prenatal exposure to dichlorodiphenyltrichloroethane (DDT) and dichlorodiphenyldichloroethylene (DDE) and neurodevelopment of Mexican farm-workers' children in California.

METHODS

Participants from the Center for the Health Assessment of Mothers and Children of Salinas study, a birth cohort study, included 360 singletons with maternal serum measures of p,p'-DDT, o,p'-DDT, and p,p'-DDE. Psychomotor development and mental development were assessed with the Bayley Scales of Infant Development at 6, 12, and 24 months.

RESULTS

We found a approximately 2-point decrease in Psychomotor Developmental Index scores with each 10-fold increase in p,p'-DDT levels at 6 and 12 months (but not 24 months) and p,p'-DDE levels at 6 months only. We found no association with mental development at 6 months but a 2- to 3-point decrease in Mental Developmental Index scores for p,p'-DDT and o,p'-DDT at 12 and 24 months, corresponding to 7- to 10-point decreases across the exposure range. Even when mothers had substantial exposure, breastfeeding was usually associated positively with Bayley scale scores.

CONCLUSIONS

Prenatal exposure to DDT, and to a lesser extent DDE, was associated with neurodevelopmental delays during early childhood, although breastfeeding was found to be beneficial even among women with high levels of exposure. Countries considering the use of DDT should weigh its benefit in eradicating malaria against the negative associations found in this first report on DDT and human neurodevelopment.

Levels of environmental contaminants in human follicular fluid, serum, and seminal plasma of couples undergoing in vitro fertilization

Environmental chemicals are thought to adversely affect human reproductive function, however there are no studies that have explored the association between failed fertilization and exposure of both partners to environmental contaminants. Therefore, we collected blood and follicular fluid from the female partner and seminal plasma from the male partner of 21 couples attending an in vitro fertilization (IVF) program, in order to determine the extent of the existence of environmental chemicals in these fluids. Any relationship to the outcome of IVF was also considered. Sera and fluids were analysed for a variety of contaminants, including polychlorinated biphenyls, pesticides, cotinine, and the steroids progesterone and estradiol. Of the couples examined, 18 had fertilizations, three of whom became pregnant. There were no fertilizations in three other couples. The contaminants most frequently found in follicular fluid, more than 50% of the samples tested, were p,p'-DDE, mirex, hexachloroethane, 1,2,4-trichlorobenzene, PCB 49, PCB 153, and PCB 180. Cadmium was detected in eight of 21 (38.1%) samples of follicular fluid whereas cotinine was detected in 18 (85.7%). Residue levels of p,p'-DDE, endosulfan I, PCB 99, PCB 138, PCB 153, PCB 180 were quantified in more than 50% of the sera samples examined. Seminal plasma was relatively free of pollutants with mirex being the most frequently detected contaminant found in seven of 21 (33.3%) samples. Mirex could not be detected in the seminal plasma of the husbands whose partner's oocytes failed to fertilize whereas significant levels of mirex were found in the seminal plasma of all couples who had a pregnancy. Cadmium was also found in the follicular fluid of these pregnant subjects. No relationship was found between follicular fluid cotinine in pregnant and non-pregnant subjects. Where identical contaminants were found in both sera and follicular fluids, the levels were about twofold higher in serum and were positively correlated in both fluids. Fertilization was negatively correlated with serum and follicular fluid p,p'-DDE whereas pregnancy was positively correlated with follicular fluid PCB 49. These data reveal that more than 50% of the population of women attending a fertility program have had exposure to environmental chemicals sufficient to produce detectable concentrations in their serum and ovarian follicular fluid. Of the chemical contaminants detected in the serum and follicular fluid of these women, p,p'-DDE was the most frequently detected, had the highest residue levels, and was associated with failed fertilization.

Sexual precocity after immigration from developing countries to Belgium: evidence of previous exposure to organochlorine pesticides

In a retrospective auxological study of 145 patients seen in Belgium during a 9-year period for treatment of precocious puberty, 28% appeared to be foreign children (39 girls, one boy) who immigrated 4 to 5 years earlier from 22 developing countries, without any link to a particular ethnic or country background. The patients were either adopted (n = 28) or non-adopted (n = 12), the latter having normal weight and height at immigration and starting early puberty without evidence of earlier deprivation. This led to the hypothesis that the mechanism of precocious puberty might involve previous exposure to oestrogenic endocrine disrupters. A toxicological plasma screening for eight pesticides detected p,p'-DDE, which is derived from the organochlorine pesticide DDT. Median p,p'-DDE concentrations were respectively 1.20 and 1.04 ng/ml in foreign adopted (n = 15) and non-adopted (n = 11) girls with precocious puberty, while 13 out of 15 Belgian native girls with idiopathic or organic precocious puberty showed undetectable concentrations (<0.1 ng/ml). A possible relationship between transient exposure to endocrine disrupters and sexual precocity is suggested, and deserves further studies in immigrant children with non-advanced puberty.

Body weight loss increases plasma and adipose tissue concentrations of potentially toxic pollutants in obese individuals

BACKGROUND

While there appears to be a consensus among scientists and clinicians that body weight loss reduces the risk of several chronic diseases, these apparently favourable effects should be balanced against any potentially harmful side effect of weight loss. In this regard, weight loss has been shown to produce an increase in blood concentration of potentially toxic organochlorine pollutants in animals that can cause prejudice to health, but human data are lacking.

METHODS

Thirty-nine obese individuals were subjected to a hypocaloric diet during 15 weeks. Blood and subcutaneous adipose tissue samples were analysed before and after treatment for 26 organochlorine compounds. A control group consisting of 57 women of similar mean age was also formed in order to compare plasma concentrations.

RESULTS

Organochlorine pollutants were found in every subject and all 19 compounds detected had their plasma concentration increased following treatment (mean body weight loss 9.5 kg), 15 of which were statistically significant. When compared with a control group, five compounds increased significantly. These observations persisted after an 18 week low-fat diet/exercise program follow-up. Increases were correlated with body weight loss (-0.3 > or = r > or = -0.6, P<0.05) and adipose tissue analyses yielded similar results, as their concentration of organochlorine compounds increased following treatment.

CONCLUSION

Body weight loss increases plasma and subcutaneous adipose tissue concentrations of organochlorine pesticides and PCBs in obese subjects. These results raise concerns about an undesired and potentially harmful side effect of weight loss in some obese patients who seem to be at greater risk of health problems than leaner subjects since they show higher organochlorine body burden.

Determinants of serum polychlorinated biphenyls and organochlorine pesticides measured in women from the child health and development study cohort, 1963-1967

We examined predictors of organochlorine concentrations in serum specimens from women who were pregnant in the 1960s and participated in the Child Health and Development Study in the San Francisco Bay Area of California. That study enrolled pregnant women at the Kaiser-Permanente Medical Facilities, conducted interviews, and drew blood specimens; these specimens were centrifuged and the resulting serum specimens were frozen and placed in long-term storage. For the current investigation, organochlorines were measured by dual-column GC-electron capture detection in specimens collected in 1963-1967 from 399 pregnant women during the second and third trimesters. Using multiple linear regression models adjusted for serum lipids, we evaluated factors predicting concentrations of 11 polychlorinated biphenyl (PCB) congeners, their sum, and several pesticides and metabolites. Variables evaluated were age, race, place of birth, date of blood draw, body mass index, occupation, past residence on a farm, parity, and duration of pregnancy at blood draw. Concentrations of highly chlorinated PCBs and the sum of the PCBs increased with age. Concentrations of certain PCB congeners, as well as the sum, were significantly higher among nonwhites and increased with calendar date of blood draw. (italic)p,p(/italic) -DDT and (italic)p,p(/italic) -DDE concentrations were about 50% higher for nonwhites compared with whites and for those born in California or the southeastern United States versus elsewhere in the United States. Higher body mass index was associated with lower concentrations of several PCBs and (italic)p,p(/italic) -DDE but with higher heptachlor epoxide and DDT levels. The increase in use of PCBs during the 1960s is apparently detectable as increasing concentrations in maternal sera between 1963 and 1967. Marked racial and regional differences in serum pesticide levels were likely caused by geographic variation in previous agricultural and vector-control uses. The relationship to body mass index appears to be complex.

Breastfeeding, exposure to organochlorine compounds, and neurodevelopment in infants

OBJECTIVE

Exposure to organochlorine compounds (OCs) occurs both in utero and through breastfeeding. Levels of hexachlorobenzene (HCB) found in the cord serum of newborns from a population located in the vicinity of an electrochemical factory in Spain were among the highest ever reported. We studied the association between exposure to OCs and breastfeeding on neurodevelopment in the 1-year-old infants of this population.

METHODS

A birth cohort including 92 mother-infant pairs was recruited between 1997 and 1999 in 5 neighboring villages (84% of possible recruits). The mental and psychomotor development of each infant was assessed at 13 months using the Bayley and the Griffiths Scales of Infant Development. OCs were measured in cord serum.

RESULTS

Dichlorodiphenyl dichloroethylene (p,p'DDE) cord serum levels were negatively associated with both mental and psychomotor development. For each doubling of a dose of p,p'DDE, we found a resultant decrease of 3.50 points (standard error: 1.39) on the mental scale and 4.01 points (standard error: 1.37) on the psychomotor scale. Exposure to polychlorinated biphenyls was only marginally associated with psychomotor development. Prenatal exposure to HCB had no effect on child neurodevelopment. Long-term breastfeeding was associated with better performance on both the mental and motor scales. Short-term breastfed infants with higher p,p'DDE levels in cord serum were associated with the lowest scores on both the mental and the psychomotor scales.

CONCLUSIONS

Prenatal exposure to p,p'DDE was associated with a delay in mental and psychomotor development at 13 months. No association was found for exposure to HCB. Long-term breastfeeding was found to be beneficial to neurodevelopment, potentially counterbalancing the impact of exposure to these chemicals through breast milk.

In utero p,p'-DDE exposure and infant neurodevelopment: a perinatal cohort in Mexico

BACKGROUND

Evidence suggests that p,p'-dichlorodiphenyldichloroethene (DDE) affects neurodevelopment in infants, although a critical exposure window has not yet been identified.

OBJECTIVES

Our goal was to assess the prenatal DDE exposure window and its effect on the psychomotor development index (PDI) and mental development index (MDI) during the first year of life.

METHODS

We recruited 244 children whose pregnancies and deliveries were uncomplicated, and whose mothers were monitored throughout the pregnancy. Participating mothers were not occupationally exposed to DDT (dichlorodiphenyltrichloroethane) but were residents of a zone in Mexico with endemic malaria. We measured serum levels of DDE before pregnancy and during each trimester of the pregnancy. We evaluated PDI and MDI of the Bayley Scales for Infant Development (BSID-II), at 1, 3, 6, and 12 months of age. We adjusted for quality of the home environment and maternal intellectual coefficient (IQ). We used generalized mixed-effects models for statistical analysis.

RESULTS

Third-trimester DDE level (7.8 +/- 2.8 ppb) was significantly higher than the level at baseline, first, and second trimesters, but the differences never exceeded 20%. Only DDE levels during the first trimester of pregnancy were associated with a significant reduction in PDI (every doubled increase of DDE level reduced the PDI 0.5 points). DDE was not associated with MDI.

CONCLUSIONS

A critical window of exposure to DDE in utero may be the first trimester of the pregnancy, and psychomotor development is a target of this compound. Residues of DDT metabolites may present a risk of developmental delay for years after termination of DDT use.

Serum concentrations of organochlorine compounds and K-ras mutations in exocrine pancreatic cancer. PANKRAS II Study Group

BACKGROUND

Organochlorine compounds such as 1,1,1-trichloro-2,2-bis(p-chlorophenyl)-ethane (p,p'-DDT), 1,1-dichloro-2,2-bis(p-chlorophenyl) ethylene (p,p'-DDE), and some polychlorinated biphenyls (PCBs) are carcinogenic to animals and possibly also to human beings. Occupational exposure to DDT may increase the risk of pancreas cancer. The high frequency of K-ras mutations in pancreatic cancer remains unexplained. We analysed the relation between serum concentrations of selected organochlorine compounds and mutations in codon 12 of the K-ras gene in patients with exocrine pancreatic cancer.

METHODS

Cases were prospectively identified in five hospitals. Mutations in K-ras were analysed by PCR and artificial restriction fragment length polymorphism. Cases of pancreatic cancer with wild-type K-ras (n=17) were frequency matched for age and sex to cases of pancreatic cancer with a K-ras mutation (n=34, case-case study). These 51 cases were further compared with 26 hospital controls (case-control comparison). Serum organochlorine concentrations were measured by high-resolution gas chromatography with electron-capture detection and negative ion chemical ionisation mass spectrometry.

FINDINGS

Serum concentrations of p,p'-DDT were significantly higher in pancreatic cancer cases with a K-ras mutation than in cases without a mutation (odds ratio for upper tertile 8.7 [95% CI 1.6-48.5], p for trend=0.005). For p,p'-DDE the corresponding figures were 5.3 (1.1-25.2, p for trend=0.031). These estimates held after adjusting for total lipids, other covariates, and total PCBs. A specific association was observed between a glycine to valine substitution at codon 12 and both p,p'-DDT and p,p'-DDE concentrations (odds ratio 15.9, p=0.044 and odds ratio 24.1, p=0.028; respectively). A similar pattern was shown for the major di-ortho-chlorinated PCBs (congeners 138, 153, and 180), even after adjustment for p,p'-DDE, but without a specific association with spectrum. Concentrations of p,p'-DDT and p,p'-DDE were similar among wild-type cases and controls, but significantly higher for K-ras mutated cases than for controls (p<0.01).

INTERPRETATION

Organochlorine compounds such as p,p'-DDT, p,p'-DDE, and some PCBs could play a part in the pathogenesis of exocrine pancreatic cancer through modulation of K-ras activation. The results require replication, but they suggest new roles for organochlorines in the development of several cancers in human beings.

Biological monitoring of pyrethroids in blood and pyrethroid metabolites in urine: applications and limitations

The objective of this study was to perform biological monitoring of subjects who are occupationally exposed to pyrethroids. The study group consisted of 30 pest control operators exposed to cyfluthrin, cypermethrin or permethrin. After exposure, 24-h urine samples were collected and 20 ml of blood was drawn. The pyrethroid metabolites cis- and trans-3-(2,2-dichlorovinyl)-2,2-dimethylcyclopropanecarboxylic acid, 3-phenoxybenzoic acid and fluorophenoxybenzoic acid were determined in the urine samples (limit of detection: 0.5 micrograms/l) by GC MS and the pyrethroids in plasma (limit of detection: 5 micrograms) GC-ECD. The concentrations of metabolites in the urine of the pest control operators ranged between < 0.5 micrograms/l and 277 micrograms/l urine. The concentrations of cyfluthrin, cypermethrin and permethrin in the plasma were below the limits of detection (< 5 micrograms/l). To test if the metabolites are specific for pyrethroid exposure, they were determined in the urine of non-exposed subjects (n = 40). In no case could pyrethroid metabolites be detected. A cyfluthrin elimination experiment showed that cyfluthrin metabolites are eliminated following first-order kinetics (t 1/2 = 6.4 h). Storage experiments demonstrate that frozen urine samples (-21 degrees C) show no significant losses of metabolites within a year. In contrast, pyrethroids stored in plasma are susceptible to further biodegeneration.

Effect of endosulfan on male reproductive development

There is experimental evidence of adverse effects of endosulfan on the male reproductive system, but there are no human data. Therefore, we undertook a study to examine the relationship between environmental endosulfan exposure and reproductive development in male children and adolescents. The study population was composed of 117 male schoolchildren (10-19 years of age) of a village situated at the foothills of cashew plantations, where endosulfan had been aerially sprayed for more than 20 years, and 90 comparable controls with no such exposure history. The study parameters included recording of clinical history, physical examination, sexual maturity rating (SMR) according to Tanner stages, and estimation of serum levels of testosterone, luteinizing hormone (LH), follicle-stimulating hormone, and endosulfan residues (70 study and 47 control subjects). Mean +/- SE serum endosulfan levels in the study group (7.47 +/- 1.19 ppb) were significantly higher (p < 0.001) than in controls (1.37 +/- 0.40 ppb). Multiple regression analysis showed that SMR scoring for development of pubic hair, testes, penis, and serum testosterone level was positively related to age and negatively related to aerial exposure to endosulfan (AEE; p < 0.01). Serum LH levels were significantly positively related to AEE after controlling for age (p < 0.01). The prevalence of congenital abnormalities related to testicular descent (congenital hydrocele, undescended testis, and congenital inguinal hernia) among study and controls subjects was 5.1% and 1.1%, respectively, but the differences were statistically nonsignificant. Our study results suggest that endosulfan exposure in male children may delay sexual maturity and interfere with sex hormone synthesis. Our study is limited by small sample size and nonparticipation.

Distribution of PCBs and organochlorine pesticides in umbilical cord and maternal serum

Polychlorinated biphenyls (PCBs) and organochlorine pesticides, such as hexachlorobenzene (HCB) and 1,1,1-trichloro-2,2-bis(4-chlorophenyl)ethylene (p,p'-DDE) are compounds widespread in the environment, highly lipophilic, and accumulate in biological systems. The newborn are exposed to these organochlorine compounds across the placenta and through breastfeeding. This study reports the levels of selected PCB congeners, p,p'-DDE and HCB in maternal blood and cord blood samples collected at delivery between November and December 1999 from 44 women living in the urban area of Antwerp, Belgium. Results show that all newborns contained detectable levels of PCBs, p,p'-DDE and HCB. The median concentration of PCBs was 450 pg/ml and ranged between 120 and 1580 pg/ml, while the median concentrations of HCB and p,p'-DDE were 70 and 490 pg/ml, respectively. Concentrations of PCBs and p,p'-DDE in cord blood (ng/ml) were positively associated with concentrations in maternal blood (ng/ml) (coefficients=0.74 and 0.92, P<0.05). We conclude that all investigated organochlorine compounds have an efficient transplacental transfer.

Serum concentrations of organochlorines in men: a search for markers of exposure

Analysis of single marker substances in serum could provide cost-effective assessment of human exposure to complex mixtures of organochlorines. We studied the serum concentrations of 10 polychlorinated biphenyl (PCB) congeners and 11 chlorinated pesticides and some of their metabolites in samples collected from 120 Swedish men (mean age 63 years, range 40-74 years) from the general Swedish population. The median concentrations of individual PCB congeners increased in the order PCB 52 < PCB 101 < or = PCB28 < PCB 105 < PCB 167 < PCB 156 < PCB 118 < PCB 138 < PCB 180 < PCB 153. The concentrations of o,p'-DDT, o,p'-DDE, p,p'-DDD, alpha-HCH and gamma-HCH were in most cases below the quantification limit (2-4 ng/g lipid). Among the other chlorinated pesticides the median concentration increased in the order oxychlordane (12 ng/g lipid) < p,p'-DDT < trans-nonachlor < beta-HCH < HCB < p,p'-DDE (586 ng/g lipid). The observed concentrations of PCB and chlorinated pesticides were in the same range as those found in similar groups of men from Sweden and Norway, but lower than those found in male populations with recent occupational exposure or high environmental exposure. Strong relationships were found between the concentrations of single mono- and di-ortho PCB congeners and groups of PCB congeners in serum. In our group of men PCB 153 was a good marker substance for the concentration of sigma PCB and sigma di-ortho PCB concentrations in serum. Moreover, among the mono-ortho PCB congeners analyzed, PCB 156 could be used as a marker for the sigma mono-ortho PCB TEQ concentrations in serum in the studied group. No useful marker substances were found among DDT compounds and other chlorinated pesticides and metabolites, except for trans-nonachlor which predicted the concentration of the metabolite oxychlordane fairly well.

Maternal serum level of 1,1-dichloro-2,2-bis(p-chlorophenyl)ethylene and risk of cryptorchidism, hypospadias, and polythelia among male offspring

1,1-Dichloro-2,2-bis(p-chlorophenyl)ethylene (p,p'-DDE) is a metabolite of the insecticide 2,2-bis(p-chlorophenyl)-1,1,1-trichloroethane (DDT) and is a ubiquitous environmental contaminant. Nearly everyone in the United States has a detectable serum level of DDE. DDE was recently found to inhibit binding of androgen to its receptor and to block androgen action in rodents. Normal development of male genitalia in mammals depends on androgen action. The authors used stored serum samples to examine the relation between maternal DDE levels during pregnancy and adjusted odds of cryptorchidism (n = 219), hypospadias (n = 199), and polythelia (extra nipples) (n = 167) among male offspring, using a nested case-control design with one control group (n = 552). Subjects were selected from the Collaborative Perinatal Project, a US birth cohort study begun in 1959-1966, when DDE levels were much higher than they are at present. Compared with boys whose mother's recovery-adjusted serum DDE level was less than 21.4 microg/liter, boys with maternal levels greater than or equal to 85.6 microg/liter had adjusted odds ratios of 1.3 (95% confidence interval (CI): 0.7, 2.4) for crypt-orchidism, 1.2 (95% CI: 0.6, 2.4) for hypospadias, and 1.9 (95% CI: 0.9, 4.0) for polythelia. For cryptorchidism and polythelia, the results were consistent with a modest-to-moderate association, but in no instance was the estimate very precise. The results were inconclusive.

A nested case-control study of non-Hodgkin lymphoma and serum organochlorine residues

BACKGROUND

The steady worldwide increase in the incidence of non-Hodgkin lymphoma during the past few decades remains mostly unexplained. Several studies suggest that there may be an association between the agricultural use of the organochlorine 1,1,1-trichloro-2,2'bis(p-chlorophenyl)ethane (DDT) and increased risk of non-Hodgkin lymphoma. We have investigated the association between risk of non-Hodgkin lymphoma and body burden of selected organochlorines in the general population in a nested case-control study.

METHODS

We measured prediagnostic serum concentrations of DDT, its metabolites, and other organochlorines, including polychlorinated biphenyls (PCBs), in 74 cases of non-Hodgkin lymphoma and 147 matched controls identified from a prospective cohort of 25,802 adults, established in 1974 in Washington County, Maryland, USA. We report results for total lipid-corrected serum concentrations of DDT and total PCBs.

FINDINGS

There was a strong dose-response relation between quartiles of total lipid-corrected serum PCB concentrations and risk of non-Hodgkin lymphoma overall (odds ratios by quartile: 1.0; 1.3 [95% CI 0.5-3.3]; 2.8 [1.1-7.6]); and 4.5 [1.7-12.0]; p for trend = 0.0008) and separately in men and in women. There was also evidence suggesting that seropositivity for the Epstein-Barr virus early antigen potentiated the effects of serum PCBs. By contrast, total lipid-corrected serum concentrations of DDT were not associated with risk of non-Hodgkin lymphoma.

INTERPRETATION

These results should be regarded as hypothesis-generating. Before causal inferences can be made about exposure to PCBs and increased risk of non-Hodgkin lymphoma, our findings require replication and the biological plausibility of the association needs further investigation.

Serum organochlorine pesticides and PCBs and breast cancer risk: results from a prospective analysis (USA)

OBJECTIVE

To prospectively evaluate relationships of organochlorine pesticides and polychlorinated biphenyls (PCBs) with breast cancer, we conducted a case-control study nested in a cohort using the Columbia, Missouri Breast Cancer Serum Bank.

METHODS

Women donated blood in 1977-87, and during up to 9.5 years follow-up, 105 donors who met the inclusion criteria for the current study were diagnosed with breast cancer. For each case, two controls matched on age and date of blood collection were selected. Five DDT [2,2-bis(p-chlorophenyl)-1,1,1-trichloroethane] analogs, 13 other organochlorine pesticides, and 27 PCBs were measured in serum.

RESULTS

Women in the upper three quartiles of hexachlorobenzene were at twice the risk of breast cancer compared to those in the lowest quartile. However, there was no evidence for a dose-response relationship, and the association was limited to women whose blood was collected close to the time of diagnosis. Women with higher serum levels of other organochlorine pesticides and PCBs showed no increased risk of breast cancer overall, although positive associations were suggested for PCB-118 and PCB-138 when blood was collected close to the time of diagnosis.

CONCLUSIONS

Results of this study do not support a role for organochlorine pesticides and PCBs in breast cancer etiology.

Improving organochlorine biomarker models for cancer research

Multivariate methods were used to predict levels of dichlorodiphenyldichloroethene (DDE) and polychlorinated biphenyl (PCB) concentrations in plasma from characteristics that included age, diet, race, reproductive history, socioeconomic status, and reported body mass index (BMI) at several decades of life before blood collection. Measurements were available for organochlorine compound (organochlorines), cholesterol, and triglycerides in plasma from 1,008 women participants in a population-based case-control study of breast cancer undertaken in 1996 to 1997 on Long Island, NY. Organochlorine compound levels were associated with age, race, lactation history, body size characteristics, and plasma lipids. PCB predictors also included fish consumption. DDE was correlated with current BMI, BMI at every decade of age from ages 20 to 60 years, and BMI-gain (from ages 20 or 30 years to 1997). In contrast, PCBs were correlated inversely with both BMI (fifth to seventh decades of age) and BMI-gain. After adjusting for covariates, DDE and PCB were both positively associated with BMI and inversely with BMI-gain; they were lowest with low BMI, high BMI-gain, and longer lactation. This pattern is consistent with a pharmacokinetic model that predicts higher body burdens during windows of highest uptake, faster elimination of organochlorine compounds in leaner women, and lowered levels accompanying BMI-gain. As a result, lifetime intake for specific organochlorine compound may lead to different plasma levels dependent on changes in body size, absolute intensity of intake, and whether exposure is ongoing (i.e., PCB) or long discontinued (i.e., DDE).