The objective of this study was to investigate Cd, Pb, and Hg levels in the breast milk of 158 lactating healthy women who were not occupationally exposed and living in eight environmentally different polluted locations of the Slovak Republic. Levels of these metals were examined in relation to selected parameters, such as: location, mother's age, parity, number of mother's teeth fillings, newborn's gender and birth weight, and smoking habits in the family. Cd and Pb levels in human milk and reconstituted infant formula were determined by GFAAS. Hg levels were measured by amalgamation technique AAS. The average concentrations of Cd, Pb and Hg in breast milk samples, taken on the 4th postpartum day, were 0.43, 4.7 and 0.94 microg/kg, respectively, and those in infant formula (n = 10) were 0.40, 5.0 and 0.25 microg/kg, respectively. Dietary weekly intakes of Cd, Pb, and Hg from breast milk and infant formula in newborn babies were also estimated. Whereas the calculated average dietary intakes of Cd, Pb, and Hg in newborn babies from breast milk and infant formula were all far lower than the appropriate PTWI values recommended by WHO/FAO, two individual breast milk samples for Pb and one breast milk sample for Hg exceeded the PTWI values. Regarding the studied parameters, only the active/passive smoking of the mother at home significantly increased Pb levels in breast milk and amalgam teeth fillings increased Hg levels in breast milk.

Dental amalgam is a mercury-based filling containing approximately 50% of metallic mercury (Hg 0 ). Human placenta does not represent a real barrier to the transport of Hg 0 ; hence, fetal exposure occurs as a result of maternal exposure to Hg, with possible subsequent neurodevelopmental disabilities in infants. This study represents a substudy of the international NIH-funded project ''Early Childhood Development and polychlorinated biphenyls Exposure in Slovakia''. The main aim of this analysis was to assess the relationship between maternal dental amalgam fillings and exposure of the developing fetus to Hg. The study subjects were mother-child pairs (N ¼ 99). Questionnaires were administered after delivery, and chemical analyses of Hg were performed in the samples of maternal and cord blood using atomic absorption spectrometry with amalgamation technique. The median values of Hg concentrations were 0.63 mg/l (range 0.14-2.9 mg/l) and 0.80 mg/l (range 0.15-2.54 mg/l) for maternal and cord blood, respectively. None of the cord blood Hg concentrations reached the level considered to be hazardous for neurodevelopmental effects in children exposed to Hg in utero (EPA reference dose for Hg of 5.8 mg/l in cord blood). A strong positive correlation between maternal and cord blood Hg levels was found (r ¼ 0.79; Po0.001). Levels of Hg in the cord blood were significantly associated with the number of maternal amalgam fillings (r ¼ 0.46, Po0.001) and with the number of years since the last filling (r ¼ À0.37, Po0.001); these associations remained significant after adjustment for maternal age and education. Dental amalgam fillings in girls and women of reproductive age should be used with caution, to avoid increased prenatal Hg exposure.

Attention-deficit hyperactivity disorder (ADHD) is associated with alterations in the metabolism of some trace elements which may participate in the pathogenesis of this disorder. The aims of the present study were to investigate the trace element status (copper (Cu), zinc (Zn), copper to zinc ratio (Cu/Zn ratio), selenium (Se), and lead (Pb)) of ADHD children and compare them with the control group. Associations between examined elements and ratings of ADHD symptoms were also assessed. Fifty-eight ADHD children and 50 healthy children (aged 6-14 years) were included in the study. The concentrations of Cu, Zn, and Se in the plasma and Pb in the whole blood were measured by atomic absorption spectrometry. We found lower Zn level (p = 0.0005) and higher Cu/Zn ratio (p = 0.015) in ADHD children when compared with the control group. Copper levels in ADHD children were higher than those in the control group, but not significantly (p > 0.05). No significant differences in levels of Se and Pb between both groups were found. Zinc levels correlated with parent-rated score for inattention (r = -0.231, p = 0.029) as well as with teacher-rated score for inattention (r = -0.328, p = 0.014). Cu/Zn ratio correlated with teacher-rated score for inattention (r = 0.298, p = 0.015). Significant associations of Se and Pb with parent- and teacher-rated symptoms were not observed. The results of this study indicate that there are alterations in plasma levels of Cu and Zn as well as significant relationships to symptoms of ADHD.

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