Effects of polychlorinated biphenyl/dioxin exposure and feeding type on infants' mental and psychomotor development.

OBJECTIVE: To evaluate the effects of in utero and lactational exposure to polychlorinated biphenyls (PCBs) and dioxins on the mental and psychomotor development of infants. DESIGN: Prenatal PCB exposure was estimated from the levels in maternal plasma during the last month of pregnancy. Postnatal PCB and dioxin exposure of breastfed infants was calculated from levels in human milk samples and the duration of breastfeeding. Infants were examined at 3, 7, and 18 months of age with the Bayley Scales of Infant Development. SETTING: General community. PARTICIPANTS: Voluntary sample of 207 mother-infant pairs. One hundred five infants were breastfed and 102 were bottle-fed. INTERVENTIONS: None. RESULTS: Higher in utero exposure to PCBs was associated with lower psychomotor scores at 3 months of age: a doubling of the PCB load resulted in a decrease of 3 points. Breastfed infants scored significantly higher on the psychomotor score at 7 months of age, compared with formula-fed infants. However, when corrected for confounders, the psychomotor score of the 66% highest-exposed breastfed infants ( > 756 pg total PCB-dioxin toxic equivalent) was negatively influenced by this postnatal exposure to PCBs and dioxins, and was comparable to the psychomotor score of the formula-fed infants. Breastfed infants also scored higher on the mental scale at 7 months of age in a dose-dependent way. There was no significant influence of the perinatal PCB and dioxin exposure on the mental outcome at 3 and 7 months of age. At 18 months of age neither the mental nor the psychomotor score was related to perinatal PCB or dioxin exposure, nor to the duration of breastfeeding. CONCLUSIONS: Prenatal PCB exposure has a small negative effect on the psychomotor score at 3 months of age. PCB and dioxin exposure through breastfeeding has an adverse effect on the psychomotor outcome at 7 months of age. The mental outcome at 7 months of age is positively influenced by breastfeeding per se; the perinatal exposure to PCBs and dioxins does not influence this outcome. At 18 months of age the development is affected neither by PCB and dioxin exposure nor by feeding type.

Neurological condition in 18-month-old children perinatally exposed to polychlorinated biphenyls and dioxins.

The neurological optimality of 418 Dutch children was evaluated at the age of 18 months, in order to determine whether prenatal and breast milk mediated exposure to polychlorinated biphenyls (PCBs) and dioxins affected neurological development. Half of the infants were breast-fed, the other half were formula-fed. PCB concentrations in cord and maternal plasma were used as a measure of prenatal exposure to PCBs. To measure postnatal exposure, PCB and dioxin congeners were determined in human milk and in formula milk. After adjusting for covariates, transplacental PCB exposure was negatively related to the neurological condition at 18 months. Although greater amounts of PCBs and dioxins are transferred via nursing than via placental passage, an effect of lactational exposure to PCBs and dioxins could not be detected. We even found a beneficial effect of breast-feeding on the fluency of movements. We conclude that transplacental PCB passage has a small negative effect on the neurological condition in 18-month-old toddlers.

Perinatal exposure to polychlorinated biphenyls and dioxins and its effect on neonatal neurological development.

Polychlorinated biphenyls (PCBs) and dioxins (polychlorinated dibenzo-p-dioxins (PCDDs), and dibenzofurans (PCDFs)) are widespread environmental contaminants which are neurotoxic in animals. Perinatal exposure to PCBs, PCDDs, and PCDFs occurs prenatally via the placenta and postnatally via breast milk. To investigate whether such an exposure affects the neonatal neurological condition, the neurological optimality of 418 Dutch newborns was evaluated with the Prechtl neurological examination. Half of the infants were breast-fed, the other half were formula-fed, representing a relatively high against a relatively low postnatally exposed group, respectively. As an index of prenatal exposure, four non-planar PCBs in cord and maternal plasma were used. These PCB levels were not related to neurological function. As measures of combined pre- and early neonatal exposure, 17 dioxin congeners, three planar, and 23 non-planar PCB congeners were determined in human milk in the second week after delivery. Higher levels of PCBs, PCDDs, and PCDFs in breast milk were related to reduced neonatal neurological optimality. Higher levels of planar PCBs in breast milk were associated with a higher incidence of hypotonia. This study confirms previous reports about the neurotoxic effects of these compounds on the developing brain of newborn infants.

Effects of polychlorinated biphenyls (PCBs) and dioxins on growth and development.

Polychlorinated biphenyls (PCBs) and dioxins are potentially toxic compounds which occur widely in the environment. Their effects on the growth and development of infants at the levels currently found in highly industrialised western countries is not well known. This Dutch multicenter study, combining animal and human studies, tries to answer this question. Animal studies showed that PCB 169, given once during pregnancy at a dose of 1.8 g kg-1 bodyweight, has an effect on developmental parameters, dopamine regulation and fertility. Effects on thyroid hormones were also found in animals, probably due to both a competitive binding of PCB metabolites to the thyroxine binding protein and increased glucuronidation. Perhaps to compensate for this, an increased diodase activity in the brain was found. Human studies involved 400 mother-infant pairs, half of them being breast-fed, the other half were fed a formula devoid of PCBs and dioxins. PCB levels were measured in serum and dioxin and PCB levels in breastmilk. Levels were found to be as high as previously found in highly industrialised countries. Growth and development were carefully documented, but no data are as yet available. In pregnant women, a significant negative correlation was found between some dioxin and PCB congeners in milk and plasma thyroid hormones, while newborn infants showed higher thyroid stimulating hormone (TSH) at higher levels of dioxin exposure. In summary, data from this combined multicenter study involving animals and humans increases our insight into the potentially negative effects of PCBs and dioxins on growth and development.

The Dutch PCB/Dioxin Study. Development of a method for the determination of dioxins, planar and other PCBs in human milk.

A method for the determination of dioxins, planar PCBs and other PCBs in human milk is described. The work is part of a big Dutch project, (seven institutes participates) in which 400 human milk samples from two areas (Rotterdam and Groningen) taken at two different times (10 and 42 days) after delivery had to be analysed for planar PCBs, dioxins and other PCBs (1st sampling) and only other PCBs (2nd sampling). Planar compounds are determined with GC/HRMS, other PCBs with GC/ECD. As type of analytes for 1st and 2nd sampling are different the method was focussed on these analytes. After fat extraction, clean up was carried out on GPC and alumina columns. Only in case of analysis of planar compounds and other PCBs, chromatography on porous graphitised carbon was carried out after which GC-HRMS (planar compounds) and GC/ECD (other PCBs) was performed; otherwise GC/ECD after alumina clean up was performed. The method is validated through recovery experiments with standards (other PCBs, labelled planar compounds), comparison of results for other PCBs obtained with the two different clean-up procedures, reproducibility of "quality control samples" for planar compounds blanc chemicals.

Dioxin and PCB levels in blood and human milk in relation to living areas in The Netherlands.

Dioxins and polychlorinated biphenyls (PCBs) are ubiquitous toxic compounds in the environment. Negative influences of these compounds on the health status of human beings have been described. Especially susceptible might be the fetus, which is exposed in utero, and the newborn breast-fed infant, since both are exposed to relatively high levels of dioxins and PCBs during a critical period of organ growth and development. We investigated PCB levels in 406 maternal plasma samples as well as PCB and dioxin levels in 172 human milk samples with relation to living area of women living for at least five years in the western industrialized part of the Netherlands or the northern more rural part. The western part was further subdivided into one urban and two highly industrialized areas. After correction for covariates, we found significantly higher levels of PCB 118 in maternal plasma as well as significantly higher levels of the dioxin-TEQ and of ten individual dioxin and PCB congener levels in human milk in the western more industrialized areas of the Netherlands compared to the northern more rural part. We did not find significant differences in planar, mono-ortho or di-ortho PCB-TEQ levels in human milk between all different areas. We conclude that significantly higher levels of a number of dioxin and PCB congeners are found in women living in industrialized areas compared to women living in rural areas in the Netherlands.

Effects of dioxins and polychlorinated biphenyls on thyroid hormone status of pregnant women and their infants.

Dioxins [polychlorinated dibenzo-p-dioxins (PCDD), dibenzofurans (PCDF)] and polychlorinated biphenyls (PCB) are potentially hazardous compounds. Animal studies have demonstrated that PCDD, PCDF, and PCB can alter thyroid hormone homeostasis. We investigated thyroid hormone levels in 105 mother-infant pairs. To estimate maternal and infant exposure, four nonplanar PCB congeners were measured in maternal plasma during the last month of pregnancy and in umbilical cord plasma. Seventeen PCDD and PCDF congeners, three planar PCB congeners, and 23 nonplanar PCB congeners were measured in human milk. Higher PCDD, PCDF, and PCB levels in human milk, expressed as toxic equivalents, correlated significantly with lower plasma levels of maternal total triiodothyronine and total thyroxine, and with higher plasma-levels of TSH in the infants in the 2nd wk and 3rd mo after birth. Infants exposed to higher toxic equivalents levels had also lower plasma free thyroxine and total thyroxine levels in the 2nd wk after birth. We conclude that elevated levels of dioxins and PCB can alter the human thyroid hormone status.

The development of five animal feed reference materials, certified for their aflatoxin B1 content.

The development of three peanut meal and two compound feed reference materials and the certification of their aflatoxin B1 content is described. The materials were prepared and certified within the Measurements and Testing Programme of the Commission of the European Communities as part of a broad activity to improve accuracy and agreement of results of measurements on food and agriculture. RM 262 (peanut meal) was prepared from uncontaminated peanut products. RM 263 and RM 264 (peanut meals) were prepared from naturally contaminated peanuts which were blended with uncontaminated ones, to achieve the desired aflatoxin B1 mass fractions. RM 375 and RM 376 (compound feeds) were made by blending decontaminated dairy feed together with commercial feed ration and contaminated dairy feed with several feed compounds, respectively. Details are given of the preparation and the investigations to verify homogeneity and stability of the materials. The certification exercise was carried out by 17 laboratories using a variety of extraction and clean-up procedures. Most laboratories used liquid chromatography as the determinative step, although operating under a variety of chromatographic conditions. A few laboratories applied thin layer chromatography with densitometric quantification. Peanut meal RM 262 was certified as containing aflatoxin B1 at a mass fraction of < 3 micrograms/kg, RM 263 at 43.3 +/- 2.1 micrograms/kg and RM 264 at 204 +/- 10 micrograms/kg. Compound feed RM 375 was certified as containing aflatoxin B1 at a mass fraction of < 1 micrograms/kg and RM 376 at 9.2 +/- 0.5 micrograms/kg. The materials can be employed either to establish or confirm a calibration curve, or to check the performance of a method.

Liquid chromatographic determination of aflatoxin M1 in milk powder using immunoaffinity columns for cleanup: interlaboratory study.

A liquid chromatographic method for determining low aflatoxin M1 concentrations in milk was evaluated in an International Dairy Federation (IDF) interlaboratory study. The study involved 16 participants from 11 countries. The method, chosen after a comparison of several methods by a preparatory group, uses an immunoaffinity column for cleanup. As the sample passes through the column, antibodies selectively bind with aflatoxin M1 (antigen) present and form an antibody-antigen complex. All other components of the sample matrix are washed off the column with water. Then, aflatoxin M1 is eluted from the column with acetonitrile, which is collected. Final determination is carried out by reversed-phase liquid chromatography with fluorescence detection. Over the tested range (80-600 ng aflatoxin M1/kg milk powder), an RSDR ranging from 11 to 23% was obtained by analyzing 24 samples (blind duplicates), 2 samples of which were blanks.

Simultaneous determination of planar chlorobiphenyls and polychlorinated dibenzo-p-dioxins and -furans in Dutch milk using isotope dilution and gas chromatography-high-resolution mass spectrometry.

A method is described for the simultaneous determination of planar chlorobiphenyls and dioxins in milk using isotope dilution and gas chromatography-high-resolution mass spectrometry (GC-MS). The method is based on gel permeation chromatography, alumina clean-up and carbon chromatography and is highly automated, making a high sample throughput possible. Data on recovery, accuracy and reproducibility of results obtained with quality control samples are presented. Data for both dioxins and planar chlorobiphenyls from the analysis of samples of Dutch milk from several areas in the Netherlands are also presented. Possible interference of the chlorobiphenyls in the determination of the dioxins in the GC-MS method is discussed.

Multimycotoxin detection and clean-up method for aflatoxins, ochratoxin and zearalenone in animal feed ingredients using high-performance liquid chromatography and gel permeation chromatography.

A sensitive and reliable method is described for the determination of aflatoxins B1, B2, G1 and G2, ochratoxin A and zearalenone in animal feed ingredients. A multi-toxin extraction and clean-up procedure is used, with dichloromethane-1 M hydrochloric acid (10:1) being used for the extraction and gel permeation chromatography being used for the clean-up. The liquid chromatographic method developed for the separation of the six mycotoxins involves gradient elution with a reversed-phase C18 column and fluorescence detection. Recoveries, repeatability and reproducibility have been determined on maize, palm and wheat. The detection limits varied depending on the type of feed.

Nutrients and contaminants in human milk from mothers on macrobiotic and omnivorous diets.

The effect of alternative dietary habits and prolonged lactation on the nutrient and contaminant concentrations in human milk was studied. The study sample consisted of mothers on macrobiotic diets, containing little or no diary products and meat, at 2-3 months postpartum (n = 9) and 9-13 months postpartum (n = 12), and mothers on omnivorous diets at 2-3 months postpartum (n = 10). Protein and zinc concentrations in breast-milk from macrobiotic mothers decreased with stage of lactation. After adjustment for stage of lactation, milk from macrobiotic mothers contained less calcium, magnesium and saturated fatty acids C15:0-C20:0, and more polyunsaturated fatty acids. Observed tendencies for lower protein and fat and higher lactose concentrations in the macrobiotic group were not statistically significant. Concentrations of vitamin B12, HCB and polychlorinated biphenyls (PCB 118, PCB 138, PCB 153 and PCB 180) were lower in the macrobiotic group. After adjustment for confounding variables, meat and fish consumption, but not dairy products, contributed to vitamin B12 concentrations. Meat and diary products strongly contributed to breast-milk concentrations of dieldrin and PCBs, fish to PCB 118, and smoking to DDT and dieldrin. Our findings suggest that breast-milk contamination could be reduced by abstinence from smoking and a moderate intake of animal products. However, risk of nutritional deficiencies rules out complete avoidance of meat, fish or diary products. Quantitative research on the effects of a reduced consumption of animal products, as well as smoking, on breast-milk contamination is warranted.

Automated clean-up procedure for the gas chromatographic-high-resolution mass spectrometric determination of polychlorinated dibenzo-p-dioxins and dibenzofurans in milk.

A highly automated extraction and clean-up method for polychlorinated dibenzodioxins and polychlorinated dibenzofurans is described. The method includes the use of gel permeation chromatography, alumina clean-up and porous graphitized carbon chromatography, followed by analysis by gas chromatography-high-resolution mass spectrometry. The procedure allows for the analysis of six milk samples per day in addition to two quality control samples and a blank. Detection limits on a fat basis for the individual congeners in milk samples are in the sub-ppt range. Long-term performance was investigated and data are given for reproducibility, precision and accuracy.

[Polychlorobiphenyls in human milk, adipose tissue, plasma and umbilical cord blood; levels and correlates]. / Polychloorbifenylen (PCB's) in moedermelk, vetweefsel, plasma en navelstrengbloed; gehalten en correlaties.

In a longitudinal study involving 17 women, PCB concentrations (PCBs 138, 153 and 180) were determined in cord blood (17 newborns), breast milk (10 women), maternal adipose tissue (8 women), maternal plasma collected during the last trimester of pregnancy (17 women) and maternal plasma collected 10 days post partum (7 women). Significant correlations were found (p less than 0.05) between PCB levels in cord blood, breast milk and adipose tissue and maternal plasma collected before birth, and between breast milk and maternal plasma collected post partum. In 2 vegetarian women the PCB levels in maternal plasma and cord blood were significantly lower than in the other women (p less than 0.05). If in future studies the PCB levels observed prove to be detrimental to child development, these correlations may offer the possibility of identifying a group of newborns at risk for occurrence of developmental defects due to PCB exposure before birth.

Automated liquid chromatographic determination of aflatoxin M1 in milk using on-line dialysis for sample preparation.

A procedure has been developed for the automated isolation of aflatoxin M1 from decreamed milk. The method uses on-line stopped flow dialysis and subsequent trace enrichment on a reverse-phase column. After a back-flush to the analytical liquid chromatography column, aflatoxin M1 is determined with fluorescence detection. Fully automated analysis is possible with reproducible dialysis recoveries above 50% (CV = 7.5%, n = 25 at the 50 ng/kg level) and determination levels of 20 ng/kg within 20 min.

Tandem capillary gas chromatography in pesticide residue analysis.

Maximum residue levels of pesticides in food and feed are often below the 0.1 ppm level. On capillary columns, the maximum injection volumes are 5-10 microliters in the splitless mode, although of course some (acceptable) overloading of the GC column occurs. Injection of larger volumes (up to 100 microliters) is possible only when the solvent can be removed whilst at the same time the compounds of interest are concentrated in a small zone. The advantage of such a procedure is obvious: the limit of detection is improved by a factor of 10-20, so a concentration step can be omitted. A Chrompack MUSIC (MUltiple Switching Intelligent Controller) kit was connected with a Tracor 550 gas chromatograph with an electron-capture detector for chlorinated compounds. Data are presented that show that gel permeation chromatography on Bio-Beads SX-3 as a clean-up medium in combination with MUSIC allows the detection of sub-ppm levels of organochlorine pesticides in grains, fats and vegetables by splitless injection of a 100-microliters sample on to the chromatographic column.

Capillary gas chromatographic determination of some chlorobiphenyls in eel fat: interlaboratory study.

A method for determination of 6 individual chlorobiphenyls in eel fat, based on saponification of the sample and determination with capillary gas chromatography, was studied collaboratively. Eleven laboratories submitted analytical results in duplicate for 6 individual chlorobiphenyls on 2 naturally contaminated eel fat samples. The reproducibility coefficient of variation was about 14% at the 1 mg/kg level for each chlorobiphenyl compound and about 23% at the 0.1 mg/kg level. For each compound, the mean recovery was about 90% with a standard deviation varying from 7 to 9%.

Rapid determination of aflatoxin B1 in Dutch feeding stuffs by high-performance liquid chromatography and post-column derivatization.

Concentrated feeding-stuff samples are extracted with chloroform. Clean-up of the extract is carried out by applying six samples in the middle of a thin-layer plate and developing it first with diethylether. After drying and cutting off a part of the plate, development is carried out in the opposite direction with a mixture of chloroform, acetone and water. The aflatoxin-containing part of the chromatogram is removed and extracted with a mixture of dichloromethane and acetone. In subsequent high-performance liquid chromatography (HPLC), the use of post-column derivatization with iodine in water results in a 50-fold increase in sensitivity, permitting determinations at the microgram/kg level. Recovery is better than 80%, and the detection limit is better than 1 microgram/kg. In the HPLC system described extracts from citrus pulp are eluted after aflatoxin B1.