Environmental exposure to metals and children's growth to age 5 years: a prospective cohort study.

In this prospective cohort study, based on 1,505 mother-infant pairs in rural Bangladesh, we evaluated the associations between early-life exposure to arsenic, cadmium, and lead, assessed via concentrations in maternal and child urine, and children's weights and heights up to age 5 years, during the period 2001-2009. Concurrent and prenatal exposures were evaluated using linear regression analysis, while longitudinal exposure was assessed using mixed-effects linear regression. An inverse association was found between children's weight and height, age-adjusted z scores, and growth velocity at age 5 years and concurrent exposure to cadmium and arsenic. In the longitudinal analysis, multivariable-adjusted attributable differences in children's weight at age 5 years were -0.33 kg (95% confidence interval (CI): -0.60, -0.06) for high (≥95th percentile) arsenic exposure and -0.57 kg (95% CI: -0.88, -0.26) for high cadmium exposure, in comparison with children with the lowest exposure (≤5th percentile). Multivariable-adjusted attributable differences in height were -0.50 cm (95% CI: -1.20, 0.21) for high arsenic exposure and -1.6 cm (95% CI: -2.4, -0.77) for high cadmium exposure. The associations were apparent primarily among girls. The negative effects on children's growth at age 5 years attributable to arsenic and cadmium were of similar magnitude to the difference between girls and boys in terms of weight (-0.67 kg, 95% CI: -0.82, -0.53) and height (-1.3 cm, 95% CI: -1.7, -0.89).

Metals and trace element concentrations in breast milk of first time healthy mothers: a biological monitoring study.

BACKGROUND: Breast milk is the best source of nutrition for the newborn infant. However, since all infants cannot be breast-fed, there is a need for background data for setting adequate daily intakes. Previously, concentration data on major essential elements and some toxic elements in breast milk, based on different analytical techniques, have been published. There is no recent study on a large number of metals and trace elements in breast milk, using a sensitive analytical method for determination of low element concentrations. METHODS: Breast milk concentrations of 32 metals and elements in early lactation (days 14-21) were determined in a random sample of first time Swedish mothers (n = 60) using inductively coupled plasma mass spectrometry (ICPMS). RESULTS: There were small inter-individual concentration variations in the macroelements Ca, K, Mg, P and S, and striking similarities across studies and over time, supporting a tight regulation of these elements in breast milk. Large inter-individual and over time differences were detected for Na concentrations, which may reflect an increase in salt consumption in Swedish women. Large inter-individual differences were also detected for the microelements Co, Cr, Mn and Mo, and the toxic metals As, Cd, Pb, Sb and V. Arsenic and B were positively correlated with fish consumption, indicating influence of maternal intake on breast milk concentrations. Observed differences in breast milk element concentrations across studies and over time could be attributed to the timing of sampling and a general decline over time of lactation (Cu, Fe, Mo, Zn), a possible lack of regulation of certain elements in breast milk (As, B, Co, Mn, Se) and time trends in environmental exposure (Pb), or in some cases to differences in analytical performance (Cr, Fe). CONCLUSIONS: This study provides reliable updated information on a number of metals and elements in breast milk, of which some have not previously been reported.

Persistent exposure to arsenic via drinking water in rural Bangladesh despite major mitigation efforts.

OBJECTIVES: Elevated arsenic levels in tube-well water in Bangladesh have prompted extensive mitigation projects. We evaluated the effectiveness of long-term mitigation efforts by longitudinally measuring arsenic exposure in pregnant women and their children, the most susceptible population groups. METHODS: The study was nested in a population-based nutrition intervention in Matlab, Bangladesh. Mother-child pairs (n = 1951) were followed from 2001 to 2003, beginning in early gestation and continuing to 5 years postpartum. We measured arsenic concentrations in urine (U-As) of the 5-year-old children by using high-performance liquid chromatography online with hydride generation and inductively coupled plasma mass spectrometry and compared them with earlier childhood U-As and maternal U-As during pregnancy. RESULTS: Children had elevated U-As at 5 years old (median = 51 µg/L, 5th-95th percentiles = 16-355 µg/L), and U-As distribution was similar to that observed in the mothers during gestation. Children's U-As at 5 years old significantly correlated with their U-As at 1.5 years old and to maternal U-As during early and late gestation. CONCLUSIONS: Despite major mitigation efforts, arsenic exposure remains highly elevated in rural Bangladesh. Further mitigation strategies are required and must be rigorously evaluated for long-term efficacy.

The association between active/passive smoking and toxic metals among pregnant women in Greece.

Exposure to toxic metals during pregnancy may have detrimental effects on foetal development. We assessed the role of sociodemographic characteristics and active and passive smoking on blood concentrations of metals (As, Cd, Pb, Hg, Sb, U, Mn and Mo). Venous blood drawn from 50 pregnant women, randomly selected from the mother-child birth cohort 'Rhea'. Extensive questionnaire data on active and passive smoking were collected. Urinary cotinine was measured to validate self-reported exposure and non-smoking status. Smokers had higher concentrations of Cd (1.0 µg/L) as compared with non-smokers (0.29 µg/L, P < 0.001) and a tendency for higher As and Hg. Among non-smokers, blood As and Hg concentrations were also associated with exposure to passive smoking in public venues and the family home and to overall greater secondhand smoke (SHS) exposure (As: 0.97µg/L among heavy-exposed compared with 0.20 µg/L among the low-exposed, P < 0.05; Hg: 2.1 µg/L vs. 0.9 µg/L respectively, P < 0.05). Controlling for fish and seafood intake altered the statistical significance but not the direction of the above associations. Smoking was associated with higher Cd concentrations in pregnant women, although the association between passive smoking and elevated As and Hg concentrations was indicative, however inconclusive.

High concentrations of essential and toxic elements in infant formula and infant foods - A matter of concern.

This study assessed concentrations in and intake of toxic and essential elements from formulas and foods intended for infants during their first 6months of life. Concentrations of the essential elements Ca, Fe, Zn, Mn and Mo were significantly higher in most formulas than in breast milk. Daily intake of Mn from formula varies from ten up to several hundred times the intake of the breast fed infant, levels that may be associated with adverse health effects. One portion of infant food provided significantly more Fe, Mn, Mo, As, Cd, Pb and U than one feeding of breast milk, but less Ca, Cu and Se. Rice-based products in particular contained elevated As concentrations. Drinking water used to mix powdered formula may add significantly to the concentrations in the ready-made products. Evaluation of potentially adverse effects of the elevated element concentrations in infant formulas and foods are warranted.

High-level exposure to lithium, boron, cesium, and arsenic via drinking water in the Andes of northern Argentina.

Elevated concentrations of arsenic in drinking water are common worldwide, however, little is known about the presence of other potentially toxic elements. We analyzed 31 different elements in drinking water collected in San Antonio de los Cobres and five surrounding Andean villages in Argentina, and in urine of the inhabitants, using ICP-MS. Besides confirmation of elevated arsenic concentrations in the drinking water (up to 210 microg/L), we found remarkably high concentrations of lithium (highest 1000 microg/L), cesium (320 microg/L), rubidium (47 microg/L), and boron (5950 microg/L). Similarly elevated concentrations of arsenic, lithium, cesium, and boron were found in urine of the studied women (N=198): village median values ranged from 26 to 266 microg/L of arsenic, 340 to 4550 microg/L of lithium, 34 to 531 microg/L of cesium, and 2980 to 16,560 microg/L of boron. There is an apparent risk of toxic effects of long-term exposure to several of the elements, and studies on associations with adverse human health effects are warranted, particularly considering the combined, life-long exposure. Because of the observed wide range of concentrations, all water sources used for drinking water should be screened for a large number of elements; obviously, this applies to all drinking water sources globally.

Impaired arsenic metabolism in children during weaning.

BACKGROUND: Methylation of inorganic arsenic (iAs) via one-carbon metabolism is a susceptibility factor for a range of arsenic-related health effects, but there is no data on the importance of arsenic metabolism for effects on child development. AIM: To elucidate the development of arsenic metabolism in early childhood. METHODS: We measured iAs, methylarsonic acid (MA) and dimethylarsinic acid (DMA), the metabolites of iAs, in spot urine samples of 2400 children at 18 months of age. The children were born to women participating in a population-based longitudinal study of arsenic effects on pregnancy outcomes and child development, carried out in Matlab, a rural area in Bangladesh with a wide range of arsenic concentrations in drinking water. Arsenic metabolism was evaluated in relation to age, sex, anthropometry, socio-economic status and arsenic exposure. RESULTS: Arsenic concentrations in child urine (median 34 microg/L, range 2.4-940 microg/L), adjusted to average specific gravity of 1.009 g/mL, were considerably higher than that measured at 3 months of age, but lower than that in maternal urine. Child urine contained on average 12% iAs, 9.4% MA and 78% DMA, which implies a marked change in metabolite pattern since infancy. In particular, there was a marked increase in urinary %MA, which has been associated with increased risk of health effects. CONCLUSION: The arsenic metabolite pattern in urine of children at 18 months of age in rural Bangladesh indicates a marked decrease in arsenic methylation efficiency during weaning.

Breast-feeding protects against arsenic exposure in Bangladeshi infants.

BACKGROUND: Chronic arsenic exposure causes a wide range of health effects, but little is known about critical windows of exposure. Arsenic readily crosses the placenta, but the few available data on postnatal exposure to arsenic via breast milk are not conclusive. AIM: Our goal was to assess the arsenic exposure through breast milk in Bangladeshi infants, living in an area with high prevalence of arsenic-rich tube-well water. METHODS: We analyzed metabolites of inorganic arsenic in breast milk and infant urine at 3 months of age and compared them with detailed information on breast-feeding practices and maternal arsenic exposure, as measured by concentrations in blood, urine, and saliva. RESULTS: Arsenic concentrations in breast-milk samples were low (median, 1 microg/kg; range, 0.25-19 microg/kg), despite high arsenic exposures via drinking water (10-1,100 microg/L in urine and 2-40 microg/L in red blood cells). Accordingly, the arsenic concentrations in urine of infants whose mothers reported exclusive breast-feeding were low (median, 1.1 microg/L; range, 0.3-29 microg/L), whereas concentrations for those whose mothers reported partial breast-feeding ranged from 0.4 to 1,520 microg/L (median 1.9 microg/L). The major part of arsenic in milk was inorganic. Still, the infants had a high fraction (median, 87%) of the dimethylated arsenic metabolite in urine. Arsenic in breast milk was associated with arsenic in maternal blood, urine, and saliva. CONCLUSION: Very little arsenic is excreted in breast milk, even in women with high exposure from drinking water. Thus, exclusive breast-feeding protects the infant from exposure to arsenic.

Mercury in human brain, blood, muscle and toenails in relation to exposure: an autopsy study.

BACKGROUND: The main forms of mercury (Hg) exposure in the general population are methylmercury (MeHg) from seafood, inorganic mercury (I-Hg) from food, and mercury vapor (Hg0) from dental amalgam restorations. While the distribution of MeHg in the body is described by a one compartment model, the distribution of I-Hg after exposure to elemental mercury is more complex, and there is no biomarker for I-Hg in the brain. The aim of this study was to elucidate the relationships between on the one hand MeHg and I-Hg in human brain and other tissues, including blood, and on the other Hg exposure via dental amalgam in a fish-eating population. In addition, the use of blood and toenails as biological indicator media for inorganic and organic mercury (MeHg) in the tissues was evaluated. METHODS: Samples of blood, brain (occipital lobe cortex), pituitary, thyroid, abdominal muscle and toenails were collected at autopsy of 30 deceased individuals, age from 47 to 91 years of age. Concentrations of total-Hg and I-Hg in blood and brain cortex were determined by cold vapor atomic fluorescence spectrometry and total-Hg in other tissues by sector field inductively coupled plasma-mass spectrometry (ICP-SFMS). RESULTS: The median concentrations of MeHg (total-Hg minus I-Hg) and I-Hg in blood were 2.2 and 1.0 microg/L, and in occipital lobe cortex 4 and 5 microg/kg, respectively. There was a significant correlation between MeHg in blood and occipital cortex. Also, total-Hg in toenails correlated with MeHg in both blood and occipital lobe. I-Hg in both blood and occipital cortex, as well as total-Hg in pituitary and thyroid were strongly associated with the number of dental amalgam surfaces at the time of death. CONCLUSION: In a fish-eating population, intake of MeHg via the diet has a marked impact on the MeHg concentration in the brain, while exposure to dental amalgam restorations increases the I-Hg concentrations in the brain. Discrimination between mercury species is necessary to evaluate the impact on Hg in the brain of various sources of exposure, in particular, dental amalgam exposure.

Inter-individual variations of human mercury exposure biomarkers: a cross-sectional assessment.

BACKGROUND: Biomarkers for mercury (Hg) exposure have frequently been used to assess exposure and risk in various groups of the general population. We have evaluated the most frequently used biomarkers and the physiology on which they are based, to explore the inter-individual variations and their suitability for exposure assessment. METHODS: Concentrations of total Hg (THg), inorganic Hg (IHg) and organic Hg (OHg, assumed to be methylmercury; MeHg) were determined in whole blood, red blood cells, plasma, hair and urine from Swedish men and women. An automated multiple injection cold vapour atomic fluorescence spectrophotometry analytical system for Hg analysis was developed, which provided high sensitivity, accuracy, and precision. The distribution of the various mercury forms in the different biological media was explored. RESULTS: About 90% of the mercury found in the red blood cells was in the form of MeHg with small inter-individual variations, and part of the IHg found in the red blood cells could be attributed to demethylated MeHg. THg in plasma was associated with both IHg and MeHg, with large inter-individual variations in the distribution between red blood cells and plasma. THg in hair reflects MeHg exposure at all exposure levels, and not IHg exposure. The small fraction of IHg in hair is most probably emanating from demethylated MeHg. The inter-individual variation in the blood to hair ratio was very large. The variability seemed to decrease with increasing OHg in blood, most probably due to more frequent fish consumption and thereby blood concentrations approaching steady state. THg in urine reflected IHg exposure, also at very low IHg exposure levels. CONCLUSION: The use of THg concentration in whole blood as a proxy for MeHg exposure will give rise to an overestimation of the MeHg exposure depending on the degree of IHg exposure, why speciation of mercury forms is needed. THg in RBC and hair are suitable proxies for MeHg exposure. Using THg concentration in plasma as a measure of IHg exposure can lead to significant exposure misclassification. THg in urine is a suitable proxy for IHg exposure.

Exposure to Lithium and Cesium Through Drinking Water and Thyroid Function During Pregnancy: A Prospective Cohort Study.

BACKGROUND: Impaired thyroid function is a common side effect of lithium medication. Recent data indicate that lithium exposure through drinking water, although providing much lower doses than the medication, may also affect thyroid hormone levels. However, the effects in susceptible groups like pregnant women are not known. METHODS: In a population-based mother-child cohort in the Argentinean Andes (n = 194), an area with varying concentrations of lithium in the drinking water, we assessed lithium exposure repeatedly during pregnancy by measuring the concentrations in blood using inductively coupled plasma mass spectrometry. The markers of thyroid function included thyrotropin (TSH), free/total thyroxine (fT4/T4), free/total triiodothyronine (fT3/T3), thyroglobulin, and transthyretin in serum, sampled at the same time. Multiple potential confounders, including exposure to arsenic, cesium, and boron (elevated in water) as well as selenium and iodine (essential for thyroid function) were considered. RESULTS: The lithium concentrations in blood [median 25 µg/L (0.0036 mmol/L); range 1.9-145 µg/L (0.000027-0.021 mmol/L)] correlated significantly with those in urine and drinking water (rs = 0.84, p < 0.001, and rs = 0.40, p < 0.001, respectively). Using linear quantile regression models, we found a positive association between blood lithium (log2 transformed) and TSH concentrations, particularly in the lowest percentiles of TSH (B = 0.20 mIU/L, [95% confidence interval 0.048-0.35] at the fifth percentile). We also found inverse associations of blood lithium with transthyretin, particularly at the highest percentiles, as well as with fT3 and T3, with less obvious variation across percentiles. Unexpectedly, blood cesium concentrations (median 111 µg/L, range 2.5-711 µg/L) were also inversely associated with fT3 and T3, particularly at the highest T3 percentiles, but not with TSH or transthyretin. Arsenic and boron exposure (also through drinking water) did not show any associations with the thyroid parameters. CONCLUSIONS: The study supports previous findings that lithium exposure through drinking water may impair thyroid function. The results regarding cesium exposure through drinking water are new. During pregnancy, impaired thyroid function may be detrimental for fetal development. The findings reinforce the need for better control of drinking water, including bottled water, as well as a health-based guideline value.

Manganese exposure through drinking water during pregnancy and size at birth: A prospective cohort study.

The essential element manganese (Mn) might be toxic at excess exposure. We assessed the impact of elevated Mn exposure through drinking water during pregnancy on birth size in a population-based cohort(n = 1695) in rural Bangladesh. Concentrations of water Mn (median = 236 µg/L, range = 7.1-6336; n = 1177) and erythrocyte Mn (median = 30 µg/kg, range = 6.3-114; n = 758) were measured using ICP-MS. In regression analyses, newborns of women in the highest tertile of water Mn (median = 1495 µg/L) were 0.49 cm (0.20 SD) shorter (B = -0.42; 95% CI: -0.77, -0.08) than those in the lowest tertile (56µg/L). The inverse association was significant in girls and also in boys of mothers with lowest hemoglobin values, likely due to higher absorption of Mn. Manganese concentrations in water and erythrocytes did not correlate, and the associations of the latter with birth size were less obvious. This study suggests that consumption of water with highly elevated Mn levels during pregnancy may impair fetal growth.

Environmental exposure to lithium during pregnancy and fetal size: a longitudinal study in the Argentinean Andes.

BACKGROUND: Lithium, used for treating bipolar disease, crosses freely the placenta and is classified as teratogenic. It is unclear to what extent environmental lithium exposure may affect fetal growth and development. OBJECTIVES: To elucidate potential effects of lithium exposure through drinking water during pregnancy on fetal size. METHODS: We developed a prospective population-based mother-child cohort (N=194) in an area with highly varying drinking water lithium concentrations (5-1600 µg/L) in northern Argentinean Andes. Blood and urinary lithium concentrations (sampled repeatedly during pregnancy) were measured using inductively coupled plasma mass spectrometry. We measured fetal size by ultrasound in second and third trimesters, and weight, length and head circumference at birth. Multivariable models were used to examine associations between lithium exposure (continuous and in tertiles) and fetal size measures. RESULTS: Lithium in maternal blood (median 25; range 1.9-145 µg/L) and urine (1645; 105-4600 µg/L) was inversely associated (apparently linearly) with all fetal measures (body, head and femur) in the second trimester, and with birth length (ß -0.53 cm per 25 µg/L increase in blood lithium, 95%CI -1.0; -0.052). An increase of 100 µg/L in blood was associated with 2 cm shorter newborns (about one standard deviation). CONCLUSIONS: Lithium exposure through drinking water was associated with impaired fetal size and this seemed to be initiated in early gestation. Further studies are warranted to confirm causality and to understand the mechanisms. If confirmed, these findings have public health relevance and emphasize the need for more data on lithium concentrations in drinking water, including bottled water.

Alkali dilution of blood samples for high throughput ICP-MS analysis-comparison with acid digestion.

OBJECTIVES: The direct dilution of blood with alkali has been introduced as an alternative to acid digestion for improvement of the analytical productivity when measuring trace elements using inductively coupled plasma mass spectrometry (ICP-MS). This study compared these two sample preparation methods for the ICP-MS determination of multiple elements in human blood and serum. METHODS: Aliquots (0.2 or 0.5 mL) of human whole blood and serum samples, including reference samples (whole blood and serum), were subjected to alkali dilution (ammonia solution) or acid digestion (nitric acid). The samples were then analysed for their concentrations of Li, B, Mg, P, S, K, Ca, Cr, Mn, Fe, Co, Ni, Cu, Zn, As, Se, Rb, Sr, Mo, Cd, Sb, Cs, Ba, Pb and U with a quadrupole ICP-MS instrument equipped with a collision/reaction cell. RESULTS: Analysis of the reference materials showed that the alkali dilution and acid digestion methods provided equally good agreement with the reference values for Mg, Mn, Co, Ni, Cu, Zn, As, Se, Rb, Mo, Cd, Sb and Pb. The alkali dilution method generally gave better agreement with the reference values for Li, B, P, S, K, Cr and U, whereas acid digestion gave better agreement for Ca, Fe, Sr and Cs. Strong associations (R(2)>0.90) between the two methods were obtained for the concentrations of Li, B, Mn, Co, Cu, As, Se, Rb, Sr, Mo, Cd, Cs and Pb in the collected human whole blood and for Li, B, Mg, P, S, K, Fe, Co, Cu, Zn, As, Se, Rb, Sr, Sb and Cs in the collected serum. CONCLUSIONS: The results suggest that the alkali dilution method is suitable for the determination of Li, B, Mn, Co, Cu, Zn, As, Se, Rb and Sr in whole blood and serum; Mo, Cd and Pb in whole blood; and Sb in serum by ICP-MS. Acid digestion is preferred for Fe and for low concentrations of Cs.

Formal recycling of e-waste leads to increased exposure to toxic metals: an occupational exposure study from Sweden.

Electrical and electronic waste (e-waste) contains multiple toxic metals. However, there is currently a lack of exposure data for metals on workers in formal recycling plants. The objective of this study was to evaluate workers' exposure to metals, using biomarkers of exposure in combination with monitoring of personal air exposure. We assessed exposure to 20 potentially toxic metals among 55 recycling workers and 10 office workers at three formal e-waste recycling plants in Sweden. Workers at two of the plants were followed-up after 6 months. We collected the inhalable fraction and OFC (37-mm) fraction of particles, using personal samplers, as well as spot samples of blood and urine. We measured metal concentrations in whole blood, plasma, urine, and air filters using inductively coupled plasma-mass spectrometry following acid digestion. The air sampling indicated greater airborne exposure, 10 to 30 times higher, to most metals among the recycling workers handling e-waste than among the office workers. The exposure biomarkers showed significantly higher concentrations of chromium, cobalt, indium, lead, and mercury in blood, urine, and/or plasma of the recycling workers, compared with the office workers. Concentrations of antimony, indium, lead, mercury, and vanadium showed close to linear associations between the inhalable particle fraction and blood, plasma, or urine. In conclusion, our study of formal e-waste recycling shows that workers performing recycling tasks are exposed to multiple toxic metals.

Exposure determinants of phthalates, parabens, bisphenol A and triclosan in Swedish mothers and their children.

Chemicals such as phthalates, parabens, bisphenol A (BPA) and triclosan (TCS), used in a wide variety of consumer products, are suspected endocrine disrupters although their level of toxicity is thought to be low. Combined exposure may occur through ingestion, inhalation and dermal exposure, and their toxic as well as combined effects are poorly understood. The objective of the study was to estimate the exposure to these chemicals in Swedish mothers and their children (6-11 years old) and investigate potential predictors of the exposure. Urine samples from 98 mother-child couples living in either a rural or an urban area were analyzed for the concentrations of four metabolites of di-(2-ethylhexyl) phthalate (DEHP), three metabolites of di-iso-nonyl phthalate (DiNP), mono-ethyl phthalate (MEP), mono-benzyl phthalate (MBzP) and mono-n-butyl phthalate (MnBP), methylparaben (MetP), ethylparaben (EthP), propylparaben (ProP), butylparaben, benzylparaben, BPA, and TCS. Information on sociodemographics, food consumption habits and use of personal care products, obtained via a questionnaire, was used to investigate the associations between the urinary levels of chemicals and potential exposure factors. There were fairly good correlations of biomarker levels between the mothers and their children. The children had generally higher levels of phthalates (geometric mean ΣDEHP 65.5 µg/L; ΣDiNP 37.8 µg/L; MBzP 19.9 µg/L; MnBP 76.9 µg/L) than the mothers (ΣDEHP 38.4 µg/L; ΣDiNP 33.8 µg/L; MBzP 12.8 µg/L; MnBP 63.0 µg/L). Conversely, the mother's levels of parabens (MetP 37.8 µg/L; ProP 13.9 µg/L) and MEP (43.4 µg/L) were higher than the children's levels of parabens (MetP 6.8 µg/L; ProP 2.1 µg/L) and MEP (28.8 µg/L). The urinary levels of low molecular weight phthalates were higher among mothers and children in the rural area (MBzP p=<0.001; MnBP p=0.001-0.002), which is probably due to higher presence of PVC in floorings and wall coverings in this area, whereas the levels of parabens were higher among the children in the urban area (MetP p=0.003; ProP p=0.004) than in the rural area. The levels of high molecular weight phthalates were associated with consumption of certain foods (i.e. chocolate and ice cream) whereas the levels of parabens were associated with use of cosmetics and personal care products.

Early-life exposure to lithium and boron from drinking water.

The transfer of lithium and boron from exposed mothers to fetuses and breast-fed infants was investigated in areas in northern Argentina and Chile with up to 700 µg lithium/L and 5-10 mg boron/L in drinking water. Maternal and cord blood concentrations were strongly correlated and similar in size for both lithium (47 and 70 µg/L, respectively) and boron (220 and 145 µg/L, respectively). The first infant urine produced after birth contained the highest concentrations (up to 1700 µg lithium/L and 14,000 µg boron/L). Breast-milk contained 40 and 60% of maternal blood concentrations of lithium and boron, respectively (i.e. about 30 and 250 µg/L, respectively, in high exposure areas), and infant urine concentrations decreased immediately after birth (120 µg lithium/L and 920 µg boron/L). We conclude that lithium and boron easily passed the placenta to the fetus, and that exclusively breast-fed infants seemed to have lower exposure than formula-fed infants.