Insecticides, polychlorinated biphenyls and metals in African lake ecosystems. I. Hartbeespoort Dam, Transvaal and Vo?lvlei Dam, Cape Province, Republic of South Africa.

Concentrations and distribution of chlorinated hydrocarbon insecticides, polychlorinated biphenyls (PCB's) and some metals were determined in two South African lakes, Hartbeespoort Dam and Vo?lvlei Dam. Water, bottom sediments, aquatic plants, aquatic insects, fish, fish-eating birds and their eggs were collected. Insecticides and PCB's were analyzed by thin layer and gas chromatography and mass-spectrometry. Analysis of metals was accomplished with atomic absorption spectrophotometry. Metals included arsenic, cadmium, copper, mangenese, lead, zinc, and mercury. The insecticide residue most commonly found in both dams were DDE, DDD, DDT, and dieldrin. Hartbeespoort had higher levesl than Vo?lvlei of insecticides and PCB's in all types of samples common to both lakes. Concentrations of PCB's in all types of samples common to both lakes. Concentrations of PCB's having six or more chlorines increased with an increase in the trophic level. Concentrations of PCB's in the brains of the African birds were greater than the average total concentration of insecticides while the opposite was true for carcasses. Biological magnification of insecticides and PCB's occurred in both lakes. Hartbeespoort Dam had higher levels than Vo?lvlei for all metals examined in bottom sediments and birds, except for copper in bird carcasses. Mercury levels in bird carcasses ranged from 2- to 5-fold greater than in fish while lead concentrations ranged from 2- to 10-fold greater.     

Insecticides,polychlorinated biphenyls and metals in African lake ecosystems. I. Hartbeespoort Dam,Transvaal and Voëlvlei Dam,Cape Province,Republic of South Africa

Concentrations and distribution of chlorinated hydrocarbon insecticides, polychlorinated biphenyls (PCB's) and some metals were determined in two South African lakes, Hartbeespoort Dam and Voëlvlei Dam. Water, bottom sediments, aquatic plants, aquatic insects, fish, fish-eating birds and their eggs were collected.Insecticides and PCB's were analyzed by thin layer and gas chromatography and mass-spectrometry. Analysis of metals was accomplished with atomic absorption spectrophotometry. Metals included arsenic, cadmium, copper, manganese, lead, zinc, and mercury.The insecticide residues most commonly found in both dams were DDE, DDD, DDT, and dieldrin. Hartbeespoort had higher levels than Voëlvlei of insecticides and PCB's in all types of samples common to both lakes. Concentrations of PCB's having six or more chlorines increased with an increase in the trophic level. Concentrations of PCB's in the brains of the African birds were greater than the average total concentration of insecticides while the opposite was true for carcasses. Biological magnification of insecticides and PCB's occurred in both lakes.Hartbeespoort Dam had higher levels than Voëlvlei for all metals examined in bottom sediments and birds, except for copper in bird carcasses. Mercury levels in bird carcasses ranged from 2- to 5-fold greater than in fish while lead concentrations ranged from 2- to 10-fold greater.     

Dioxin-like components in human breast milk collected from Hong Kong and Guangzhou

The H4IIE rat hepatoma cell line was employed as a cell model to screen 7-ethoxyresorufin O-deethylase (EROD)-TCDD equivalents (EROD-TEQ) of human breast milk samples collected from Hong Kong and Guangzhou, China. The screening methods employed a 96-well plate spectrofluorometer-EROD assay. For cell-line validation, our results demonstrated a dose-dependent increase in the Ah receptor-mediated response (i.e., CYP1A1 mRNA and EROD) of the cells upon exposure to a number of known Ah receptor agonists, including 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD), 2,3,7,8-tetrachlorodibenzothiophene, benzo[a]pyrene, and beta-naphthaflavone. TCDD induced CYP1A1 mRNA and EROD was in a close positive correlation (r=0.98). For the screening of dioxin-like compounds, breast milk samples collected during lactation weeks 3-5 were used. One hundred (from Hong Kong) and 48 (from Guangzhou) breast milk samples were assayed, of which 65% and 68% of the samples, respectively, showed detectable dioxin-like activities using the H4IIE cell EROD screening method. For sixty-five samples from Hong Kong the mean EROD-TEQ values ranged from 58.1 to 96.5 pg/g of milk fat for those aged 21-36 years while 32 samples from Guangzhou had mean values of 98.8-202.1 pg/g of milk fat. In comparisons of the EROD-TEQ values for different age groups from both cities, there were no significant differences (P<0.05). However, the mean and median EROD-TEQ values of the Guangzhou population were in general higher than those of the Hong Kong population. The results of the present study indicate that it is feasible to use the H4IIE cell-line as a model for screening dioxin-like compounds in human breast milk. In addition, the method is rapid and cost-effective, particularly for a routine and high-throughput sample screening analysis, compared to the costly and time-intensive chemical analytical techniques.     

Total phospholipid analysis in human milk without acid digestion

A colorimetric method for measuring the organic phosphorus in human milk without acid digestion was studied. Human milk samples were assayed and compared to phosphatidylcholine, phosphatidylethanolamine, and sphingomyelin standards. Spectral and calibration curves prepared from phospholipid standards were equivalent. Absorption maxima occurred between 720 and 740 nm. A reproducibility study of twenty total lipid samples had a coefficient of variation of 3.8%. Phosphorus ranged from 4.7 to 5.5 micrograms with a mean +/- SD of 5.2 +/- 0.2 micrograms P. The recovery of phosphatidylcholines added to 10 mg samples of human milk triacylglycerols ranged from 99.0 to 102.1%. The results from the new method were comparable to those obtained by a modified Fiske and Subbarow method for measuring inorganic phosphorus after sulfuric acid digestion of the milk lipids. We concluded that the new method provides a satisfactory alternative for the determination of organic phosphorus in human milk.     

Copper and zinc content in human milk in Croatia

The aim of this paper was to research whether there had been any statistically significant difference in the content of Cu and Zn in human milk depending on the social status of women (refugee and non-refugee), age, number of deliveries, days after delivery, weight gained by nursing women and smoking habits, as well as whether the infants had received sufficient quantities of these elements. The elements were determined by flame atomic absorption spectroscopy. The samples were collected in the Clinical Hospital Osijek and Refugee Centre Nabrde, near Osijek, Eastern Croatia. The Cu in human milk ranged from 0.27 mg/l to 1.35 mg/l, and Zn from 0.62 mg/l to 15.0 mg/l. The mean levels of Cu and Zn for each group, formed according to the results of the questionnaire are presented too. Calculated daily dietary intake of these elements accords with the RDA.     

Mirex in human milk in upstate New York

Human milk and colostrum samples were collected from women living in the vicinity of Albany, Oswego, and Rochester, New York. Analysis by a highly sensitive method based on glass-capillary gas chromatography with electron-capture detection showed that mirex was present only at very low concentrations (generally less than 0.1 ng/g wet weight whole milk). Gas chromatographic/mass spectrometric analysis with both a quadrupole spectrometer and a double-focusing instrument confirmed the presence of mirex in three samples which had been shown by electron-capture analysis to contain more than 1 ng of mirex/g wet weight.     

Mono-ortho- and non-ortho-substituted polychlorinated biphenyls in human milk from Mohawk and control women: Effects of maternal factors and previous lactation

Fifty-four individual human milk samples from 50 mothers (20 Mohawks and 30 controls) were analyzed for four non-ortho- and eight mono-ortho-substituted polychlorinated biphenyls (PCBs). Mean total coplanar PCBs concentrations were 49 ng/g and 55 ng/g lipid for Mohawk and control women, respectively. A statistical evaluation of all analytical data reveals no significant difference of total coplanar PCB level between Mohawk and control women. The level of these contaminants is influenced by the age of the mother, number of breastfed children, and length of nursing period. Older women, primiparae, and cigarette smokers had higher levels of coplanar PCBs. In general, women had higher levels of coplanar PCBs in the first lactation and in the earlier samples of a given lactation, while levels declined both with duration of breast-feeding and with number of children nursed.The contribution of individual non-ortho- and mono-ortho-substituted PCB congeners to the total calculated toxic equivalent values (TEQ) was assessed for the breast milk samples. The levels of polychlorinated dibenzo-p-dioxins (PCDDs) and polychlorinated dibenzofurans (PCDFs) in human milk of pooled specimens from Los Angeles, California and Binghamton, New York, widely separate cities in the United States (Schecter et al. 1989), were presented for reference purpose. The main contributions to the TEQ were PCB congeners #118 (25.8 pg/g lipid), #126 (25 pg/g lipid), #105 (10.8 pg/g lipid), and #156 (7.4 pg/g lipid). Collectively, these compounds accounted for 70% of the TEQ values. Based on the TEFs proposed by Safe (1990), the overall TEQs calculated for the monitored PCBs, were about five times those due to total PCDD/Fs.     

Polychlorinated biphenyls (PCBs) and dichlorodiphenyl dichloroethene (DDE) in human milk: effects of maternal factors and previous lactation.

The authors measured polychlorinated biphenyls (PCBs) and dichlorodiphenyl dichloroethene (DDE) in maternal serum, cord blood, placenta, and serial samples of breast milk from 868 women. Almost all samples of breast milk showed detectable levels of both chemicals. Overall, values for DDE in this study are within the range of those found previously, whereas those for PCBs are somewhat higher. Possible causes of variation in levels were investigated. For DDE, older women, Black women, cigarette smokers, and women who consumed sport fish during pregnancy had higher levels; only age and race showed large effects. For PCBs, older women, women who regularly drink alcohol, and primiparae had higher levels. In addition, both chemicals showed modest variation across occupational groupings. Casual exposure to a PCB spill did not result in chemical levels different from background. In general, women have higher levels in their first lactation and in the earlier samples of a given lactation, and levels decline both with time spent breast-feeding and with number of children nursed. These striking declines are presumably a measure of exposure to the child.     

DDT residues in human milk samples from Delhi,India

Possible contamination of human milk through the excretion of DDT and its metabolites is a concern in India, where DDT is widely used as an insecticide. To assess this risk, milk samples collected from 60 lactating women admitted to hospitals in Delhi were quantitatively analyzed. 55 of the 60 milk samples showed evidence of residues of pp'DDE (mean, 0.176 + or - 0.382 ppm), op'DDT (mean, 0.046 + or - 0.011 ppm), and pp'DDT (mean, 0.122 + or - 0.434 ppm). The mean residue level in milk fat (mg/kg fat) was 7.280 + or - 23.240, 1.428 + or - 2.697, and 1.597 + or - 5.936, respectively. A large variation in individual values was observed. The finding that pp'DDE is the DDT metabolite excreted into human milk at the highest level is consistent with previous research. Daily intake of total DDT averaged 0.062 mg/kg of body weight--a value that is 12 times higher than the acceptable level of DDT (0.005 mg/kg/day) set by the World Health Organization. Although no harmful effects of DDT have been recorded to date in breastfed infants in India, preventive measures aimed at reducing the body burden of DDT in lactating women are urged.     

Microbiological quality of human milk from a Brazilian milk bank

OBJECTIVE: The objectives of the present study were to determine the prevalence of potentially pathogenic microorganisms that indicate the hygienic and sanitary conditions of human milk samples collected at a Human Milk Bank. METHODS: Three hundred and thirty eight (338) samples of human milk collected from a milk bank in a maternity in the municipality of Goiania, in the state of Goias, Brazil were submitted to microbiological analysis. The latter were plated on McConkey agar according to the type of bacteria. Among the total number of samples collected, 194 consisted of raw milk and the remaining 144 were pasteurized milk. RESULTS: The presence of Staphylococcus spp., Streptococcus spp., yeasts and molds, and Enterobacteriaceae was verified in the raw milk samples. Staphylococcus aureus were isolated in 10 (5.2%) samples, Staphylococcus epidermidis in 28 (14.4%) samples, Streptococcus spp. in three (1.6%) samples, yeasts and molds in 43 (22.2%) and Enterobacteriaceae in 49 (25.3%) samples. In a hundred and forty four (144) samples which underwent thermal treatment Staphylococcus aureus was detected in five (3.5%) samples, Staphylococcus epidermidis in 15 (10.4%), Staphylococcus lugdenensis in two (1.4%), Streptococcus spp. in four (2.8%), yeasts and molds in 37 (25.7%), and Enterobacteriaceae in nine (6.3%). CONCLUSIONS: Analysis indicated a high degree of contamination in raw human milk, and as for the pasteurized milk, despite elimination of the great majority of potentially pathogenic microorganisms, the percentage of yeasts and molds was higher than in raw milk, demonstrating that a lower degree of initial contamination would be necessary for pasteurization to be an efficient means of microbiological control.     

Triacylglycerol composition in colostrum, transitional and mature human milk

OBJECTIVE: Milk triglycerides from colostrum, transitional and mature human milk, were analyzed and compared in order to determine the differences in triacylglycerol composition throughout lactation. SETTING: Department of Food and Nutrition, University of Barcelona, Spain, and Neonatology Department of the University Hospital of Granada, Spain. SUBJECTS: Twenty-two healthy lactating women aged 21-35. Design and interventions: The triacylglycerol profiles of 47 breast milk samples including colostrum (1-3 days), transitional milk (7-10 days) and mature milk (25-60 days) were analyzed by high-performance liquid chromatography (HPLC), with light-scattering detection (LSD). RESULTS: Significant differences regarding several triglycerides were found between three milk classes when the Kruskal-Wallis nonparametric test was applied to 47 human milk samples that had been compared using the complete chromatographic triacylglycerol profile. The ANOVAS for each equivalent carbon number (ECN) group of triglycerides revealed significant differences between colostrum, transitional milk and mature milk. By the discriminant analysis of triacylglycerol percentages, in 19 colostrum samples, 14 transitional milk samples and 14 mature milk samples, three milk types were distinguished, and three triglycerides (peak no. 4, LnOO and SOO) were found to be the most predictive variables over all the triacylglycerol profile or ECN groups. CONCLUSIONS: Each state of lactation shows a specific profile of triacylglycerol composition in human milk. However the two most abundant triacylglycerides in colostrum, POO and POL, which account for more than 49% of the total, are also dominant in transitional (34%) and mature milk (42%).     

Determination of total potentially available nucleosides in human milk from Asian women

OBJECTIVE: The objective was to measure the total potentially available nucleosides (TPAN) in breast milk from Asian women. METHODS: One hundred sixty milk samples were collected from 135 healthy, lactating women in Hong Kong, the Philippines, and Singapore at four stages of lactation: colostrum (1 to 3 days postpartum), transitional (7 to 10 days postpartum), early mature (28 to 35 days postpartum), and late mature (90 to 100 days postpartum). Samples were pooled by site and stage of lactation before analysis. RESULTS: The mean TPAN concentration was 203 microM/L (69.4 mg/L corrected for recovery). Average TPAN concentrations were 171.9 microM/L in colostrum, 208.1 microM/L in transitional milk, 221.6 microM/L in early mature milk, and 210.6 microM/L in late mature milk, with no notable differences between countries. The major sources of nucleosides were RNA (43.3% of TPAN) and free nucleotides (39.9% of TPAN). The average percentages of cytidine, uridine, guanosine, and adenosine monophosphates were 44.5%, 23.1%, 16.5%, and 16.1% of TPAN, respectively. The sources of nucleosides and percentages of nucleotide bases were similar for all stages of lactation. Over 91% of the TPAN was present in the non-cellular component except in colostrum. CONCLUSIONS: The average TPAN level in Asian women is similar to that in European and American women, and free nucleotides in human milk represent less than half of the TPAN.     

Flavin composition of human milk

The identity and quantity of greater than 95% of the flavins present in human milk were assessed by acid-phenol extractions followed by high-performance liquid chromatography. Flavin adenine dinucleotide (FAD) and riboflavin were the predominant flavins, followed by 10-(2'-hydroxyethyl)-flavin. In addition, traces of 7 alpha- and 8 alpha-hydroxyriboflavins (7-hydroxymethylriboflavin and 8-hydroxymethylriboflavin, respectively) were detected. The flavin content of human milk samples in this study was higher than contents reported in earlier studies where no correction for the internal fluorescence quenching of FAD was made. This finding may have implications for dietary recommendations concerning both lactating women and infants. In practical terms, the types and amounts of flavins in human milk are very similar to those recently reported for cow milk.     

Macronutrient composition of human milk from Korean mothers of full term infants born at 37-42 gestational weeks

BACKGROUND/OBJECTIVESBreast milk is the best available food for optimum growth and development of infants and the breastfeeding rate is increasing in Korea. The purpose of this study is to measure the concentrations of macronutrients and to evaluate their changes according to lactation period in breast milk from lactating Korean women.SUBJECTS/METHODSMilk samples were obtained from 2,632 healthy lactating women (mean age; 32.0 ± 3.3 years), where the lactating period was up to a period of 8 months, who also volunteered to participate in the Human Milk Macronutrient Analysis Research. Lactose, protein, fat and water content in the breast milk samples were analyzed with infrared spectrometry using MilkoScan FT-2.RESULTSThe mean macronutrient composition per 100 mL of mature breast milk was 7.1 g for lactose, 1.4 g for protein and 3.0 g for fat, and energy content was 61.1 kcal. The protein concentration was significantly lower in milk samples at 1-2 weeks (2.0 g/dL) to 2-3 months (1.4 g/dL) than those at 0-1 week (2.2 g/dL), but it was similar among samples from 3-4 months to 7-8 months (1.3 g/dL). Mean lipid levels varied among different lactational period groups (2.7-3.2 g/dL), but presented no significant difference. Lactose concentration in the milk samples did not differ with lactation period. Maternal body mass index was positively related to protein and lipid breast milk contents, but was negatively related to lactose content. General linear models examining the associations between maternal variables and milk macronutrient content revealed that lactation period had a major impact on protein and lipid, but not on lactose content in breast milk.CONCLUSIONSThese results warrant future studies to explore factors that may be associated with changes in macronutrient content in human milk.     

Compartmentalization and quantitation of protein in human milk

Human milk protein was determined by three colorimetric methods and by Kjeldahl analysis. The distribution of nitrogen (N) and protein was determined within various milk compartments. Total N, whey, casein, nonprotein nitrogen (NPN), cell N and N in the fat fraction were analyzed by micro-Kjeldahl analysis after a series of centrifugation and ultracentrifugation separations. Fresh milk samples (colostrum, transitional milk and mature milk) were centrifuged at 500 X g to separate milk cells and at 5000 X g to skim the milk. Decelled milk and skimmed milk were ultracentrifuged at 189,000 X g to separate fat and casein micelles from whey. NPN was analyzed after trichloroacetic acid precipitation. Whole milk, decelled milk, skimmed milk and whey were analyzed for protein with the Lowry method, modified for fat-containing samples, the Bradford dye-binding assay (Bio-Rad) and the Pierce bicinchoninic acid (BCA) assay. Cell nitrogen had a tendency to be lower in mature milk than in colostrum. Colostrum contained only 6% casein protein, whereas mature milk contained 13%. Fat from skimming was lower in N than fat from ultracentrifugation. Average NPN levels were similar for milk from all three lactation periods, and constituted 10% of colostrum N and 25% of mature milk N. Protein determined by the Bio-Rad method on whole milk samples had the lowest variability (square root MSE) when correlated to Kjeldahl values. All three assays had lower variability when analyzing whey and skimmed milk than when analyzing whole milk. The Lowry method and the Bio-Rad method had low variability for whey and skimmed milk samples, but the Lowry method yielded analytical values closest to Kjeldahl protein values. The BCA method consistently overestimated Kjeldahl protein by 30%.     

Ethinyl estradiol in human milk and plasma after oral administration

In order to estimate the concentration of ethinyl estradiol in milk, four fully lactating women were given an oral contraceptive containing 50 μg ethinyl estradiol + 4 mg megestrol acetate, starting two months after delivery, and four women who wanted to stop nursing after a lactation period of 6–18 months were given one tablet of 500 μg ethinyl estradiol. Milk and blood samples were taken simultaneously after 3, 7, 11 and 23 hours. The concentration of ethinyl estradiol in plasma and milk were estimated by radioimmunoassay. The method for the assay of ethinyl estradiol in milk is evaluated in this paper.The concentration of ethinyl estradiol in milk from the women taking the oral contraceptive was below the detection limit of the assay. In the women taking 500 μg of ethinyl estradiol, the plasma:milk ratio of ethinyl estradiol was found to be about 100:25. The relative dose of ethinyl estradiol ingested by a fully nursed baby, when its mother takes an oral contraceptive containing 50 μg of ethinyl estradiol, has been calculated to be about 10 ng per day, which is 0.02 per cent of the dose given to the mother.     

Concentrations of iron,copper and zinc in human milk and powdered infant formula

Concentrations of iron, copper and zinc were determined in 56 samples of mature human milk from Canarian women and 5 samples of powdered infant formula. According to the literature our data fall within the normal limits in each kind of milk. The mean concentration of Fe, Cu and Zn of powdered infant formula was significantly higher than those concentrations found in the human milks. Significant differences among the concentrations of the studied metals for the milks of considered mothers were observed. The Fe, Cu and Zn intakes of infants fed with human milk are lower than the requirements recommended by the Food and Nutrition Board (1989). However, the infants fed with powdered infant formula had consumed an adequate intake of Fe and Cu. A progressive decrease of the metal concentrations with the lactation stage was observed. The human milk obtained in spring presented Fe and Zn concentrations lower than in autumn, which could be due to changes in nutritional habits of the mothers. Age of mother and number of previous children seem to influence the Zn and Cu concentrations of human milk.     

Concentrations of iron, copper and zinc in human milk and powdered infant formula

Concentrations of iron, copper and zinc were determined in 56 samples of mature human milk from Canarian women and 5 samples of powdered infant formula. According to the literature our data fall within the normal limits in each kind of milk. The mean concentration of Fe, Cu and Zn of powdered infant formula was significantly higher than those concentrations found in the human milks. Significant differences among the concentrations of the studied metals for the milks of considered mothers were observed. The Fe, Cu and Zn intakes of infants fed with human milk are lower than the requirements recommended by the Food and Nutrition Board (1989). However, the infants fed with powdered infant formula had consumed an adequate intake of Fe and Cu. A progressive decrease of the metal concentrations with the lactation stage was observed. The human milk obtained in spring presented Fe and Zn concentrations lower than in autumn, which could be due to changes in nutritional habits of the mothers. Age of mother and number of previous children seem to influence the Zn and Cu concentrations of human milk.     

Evaluation of xenobiotics in human milk and ingestion by the newborn

Summary Background Many human milk benefits have been well documented; nevertheless the newborn potential risk to the xenobiotic exposition may be relevant and it requires a biological monitoring in general prevention. Concerning this problem, attention should be paid to mycotoxins and heavy metals. Aim of the study Assessing the presence of the xenobiotics aflatoxins, ochratoxin A, lead and cadmium in human milk, defining their level of contamination and evaluate the potential risk for the newborn derived from this xenobiotic ingestion. Methods A study has been carried out on lactating women randomly selected in seven hospitals in Lombardy (Northern Italy). Two hundred and forty–seven puerparae were recruited; 231 women participated in the study. Womens milk samples on the third or fourth day after delivery were tested to determine aflatoxins and ochratoxin A levels. Lead and cadmium were determined in 143 women because supplemental milk could be taken only from these women. Results Aflatoxin B1 (11.4 ng/l) and aflatoxin M1 (194 ng/l) were found only in one sample,while ochratoxin A was detected in 198 samples (85.7 %) at an average value of 6.01 ± 8.31 ng/l. A total of 75.7% of samples were positive for lead; the cadmium situation was better with 87.4% of the sample with values below detection limits (2 µg/l). A high percentage of babies (71 %) are exposed to mycotoxin levels on day 6 greater than the TDI value of 0.2 ng/kg b.w. Lead and cadmium presence in human milk presented risk respectively for 8% and 0.7% of newborns on the fourth day; 9.5% and 1.4% on the sixth day. Conclusions The study points out that mycotoxins and lead are present in maternal milk, and the data confirm the need to continue biological monitoring in general prevention.     

Levels of organochlorine insecticides in milk of mothers from urban and rural areas of botucatu,SP, Brazil

The organochlorines DDT and hexachlorocyclohexane (HCH) were determined in mothers' milk in 21 women from rural towns and 21 from urban Botucatu, Sao Paulo, Brazil, and correlated with environmental factors such as prevalence of house spraying, smoking, and agricultural work. Extraction and gas chromatography methods were those published by the U.S. EPA. Average DDT levels in urban milk samples were 34.9 ppb, and in rural milk 16.5 ppb. Higher meat intake was probably a factor in higher urban yield. In contrast, rural levels of HCH were 46.3 ppb, compared to 14.4 ppb in urban mothers. DDT levels were consistently lower in women who had nursed 3 or more children, than those with 1 or 2. House spraying was related to higher DDT levels in rural areas only. DDT levels were much higher in women who smoked. HCH content was higher in younger women than older, and in houses that had been sprayed, especially in rural zones, where spraying programs are run by the public health authorities. Dieldrin was detected in only 3 urban samples.