Mercury and selenium in fish from the eastern part of the Adriatic Sea: A risk-benefit assessment in vulnerable population groups.

The study examines the levels of total mercury (Hg) and selenium (Se) in the muscle tissue of 12 commercially important fish species (n = 717) from 48 locations in the eastern Adriatic Sea, as a function of fish species, size and habitat. Risks and benefits of fish consumption regarding Hg and Se in children (7 years) and women of reproductive age (30 years) were also evaluated. All samples but one were compliant with the European regulatory limit for Hg in fish muscle. Concentrations (µg g-1 ww) of Hg (range: 0.014-1.37) and Se (range: 0.184-1.12) and Se:Hg molar ratios in fish were associated with habitat type. Demersal species had the highest Hg and the lowest Se concentrations, while pelagic species had the lowest Hg concentrations, highest Se concentrations and Se:Hg molar ratios. All species had Se:Hg molar ratios above 1 (range: 1.4-66.9) and a selenium health benefit value (HBVSe) above zero (range: 3.3-9.3), indicating Se excess after Hg sequestration. The intake of two meals per week of small pelagic-neritic and bento-pelagic fish is estimated to be a valuable source of essential Se, and does not pose a risk from toxic Hg exposure in children and women during the vulnerable reproductive period. Due to the low Hg and favorable Se:Hg molar ratio and HBVSe index, small pelagic species offer a good risk to benefit ratio of fish consumption and could be considered an optimal choice in these sensitive subpopulations.

Mercury Exposure Assessment in Mother-Infant Pairs from Continental and Coastal Croatia.

The main source of mercury (Hg) exposure in the general population is fish. Another possible source is dental amalgam. Here, we compare the levels of Hg and selenium (Se) in samples of maternal and fetal origin collected shortly after childbirth of healthy postpartum women in the coastal (n = 96) and continental (n = 185) areas of Croatia related to maternal seafood/fish consumption. We also evaluated Hg concentrations and maternal serum metallothionein (MT2) concentrations in relation to the number of dental amalgam fillings, and MT2A-5A/G (rs28366003) polymorphism. The levels of Hg and Se in maternal hair and blood/serum, placenta and cord blood/serum increased in relation to increasing fish consumption with the highest values in subjects from the coast. The concentrations of each element and between elements correlated across the matrices. Increasing amalgam number correlated linearly with increased Hg levels in maternal and cord serum and was not associated with serum MT2. No association of MT2A-5A/G polymorphism and Hg or Se levels were found. The results confirmed higher fish consumption in coastal vs. continental Croatia and increases of both Hg and Se related to fish consumption in all analyzed samples. Increased blood Hg reflected the predominant MeHg share from seafood, while increased serum Hg matched exposure from dental amalgams.

Use of human milk in the assessment of toxic metal exposure and essential element status in breastfeeding women and their infants in coastal Croatia.

Pregnant and lactating women and infants are vulnerable population groups for adverse effects of toxic metals due to their high nutritional needs and the resultant increased gastrointestinal absorption of both, essential and toxic elements. Although breastfeeding is recommended for infants worldwide, as human milk is the best source of nutrients and other required bioactive factors, it is also a pathway of maternal excretion of toxic substances including toxic metals and thus a source of infant exposure. The aim of this research was to assess health risks in breastfeeding women in the coastal area of the Republic of Croatia and their infants (N=107) due to maternal exposure to Cd and Pb via cigarette smoking, and Hg via seafood and dental amalgam fillings, and their interaction with essential elements. Biological markers of exposure were the concentrations of main toxic metals Pb, Cd and Hg in maternal blood and three types of breast milk throughout lactation stages. Biological markers of effects were the levels of essential elements Ca, Fe, Cu, Zn and Se in maternal serum and breast milk. With regard to cigarette smoking as a source of exposure to Cd and Pb, there were effects of smoking on Cd concentration in blood and correlations between the smoking index and Cd concentrations in maternal blood (ρ=0.593; P<0.001) and mature milk (ρ=0.271; P=0.011) and Pb concentration in transitional milk (ρ=0.280; P=0.042). Regarding fish, we found correlations between weekly consumption frequency and total Hg concentrations in maternal blood (ρ=0.292; P=0.003) and mature milk (ρ=0.303; P=0.003). The number of dental amalgam fillings correlated with total Hg concentrations in colostrum (ρ=0.489; P=0.005) and transitional milk (ρ=0.309; P=0.018). As for the essential element status, only Se levels in maternal serum decreased by 10% in persons who continued smoking during pregnancy compared to non-smokers. In conclusion, the levels of main toxic metals Cd, Pb and Hg and essential elements Ca, Fe, Cu, Zn and Se in maternal blood and three types of breast milk samples in the studied area of coastal Croatia showed no risk of disrupted essential element levels with regard of toxic metal exposure in both breastfeeding women and their infants.

Oral cadmium exposure during rat pregnancy: assessment of transplacental micronutrient transport and steroidogenesis at term.

Diet is the main source of cadmium (Cd) exposure. Gastrointestinal absorption increases during pregnancy. Cadmium accumulated in the placenta may interfere with nutrient transport to the foetus. Data on the potential of Cd to act as a steroid disruptor of pregnancy are limited. We evaluated the effects of oral Cd exposure during pregnancy on placental function in micronutrient transfer to the foetus and steroidogenesis in Wistar rats (regular 4-day cyclers) that mated with unexposed males. Pregnant rats were randomly assigned to a Cd group exposed orally to 50 mg Cd l(-1) (CdCl(2)xH2O dissolved in demineralized water), ≈ 7.5 mg Cd kg(-1) a day, during 20 days of gestation and control (supplied with demineralized water). Non-pregnant rats were treated under the same experimental conditions. On day 20, all of the rats were killed and samples were taken for element analyses (by electrothermal atomic absorption spectrometry). Progesterone and testosterone were measured in serum and placenta-derived samples (by immunoenzymometric assay and/or enzyme-linked immunosorbent assay). In the exposed rats, Cd increased in blood and organs, more in pregnant rats, and in placenta and foetus whereas zinc increased in liver. Iron decreased in maternal organs and in foetus, whereas zinc decreased in maternal kidney and placenta. Liver copper was lower and kidney copper higher in all pregnant vs. non-pregnant rats. Steroids in serum and placenta did not change. In conclusion, oral Cd exposure during rat pregnancy does not affect progesterone and testosterone at term. Transplacental iron and zinc handover are disrupted, which may put at risk the maintenance of foetal nutrition and viability.

Cadmium in placenta- a valuable biomarker of exposure during pregnancy in biomedical research.

Rats were exposed to cadmium (Cd) during pregnancy orally (50 ppm Cd in drinking water from gestation day [GD] 1-20) or parenterally (5 mg/kg sc during GD 1-19 or on GD 16). Cadmium levels were measured in blood, placenta, and fetus at the end of exposure. Human studies comprised of two cohorts of healthy Croatian postpartum women in the continental versus coastal area; in these women, Cd levels were measured in maternal blood, placenta, and cord blood. Cadmium in rat placenta was 10-fold higher following parenteral versus oral exposure, with highest value after exposure in mid pregnancy. The values were 10-fold higher in placenta than blood, and the fetus had ≤10% of blood metal levels. Cadmium levels in human placenta noted increased values in smokers that were 10- to 20-fold higher than in maternal blood and in cord blood were very low (<0.1 ppb). In nonsmokers, different Cd levels in placenta and blood in coastal versus continental area were found due to dietary intake. Data showed that Cd in placenta is a reliable biomarker of exposure following oral and parenteral treatment during pregnancy in rats and in human biomonitoring that includes prenatal assessment. In addition, tobacco smoking is a prominent source of metal exposure. Cd levels in placenta are also a valuable biomarker of metal dietary exposure related to specific dietary habits and soil characteristics.