Oxidative Stress Levels Induced by Mercury Exposure in Amazon Juvenile Populations in Brazil.

Oxidative stress can be induced by mercury (Hg) exposure, including through fish consumption (diet), leading to health risks. The objective of this study was to evaluate the association between oxidative stress biomarkers and dietary Hg exposure levels in riverine children and adoluiaescents at Madeira River (RO/Brazil). Population from three riverine local communities presenting different fish consumption frequencies was sampled. Hg was determined in blood (ICP-MS) and glutathione (GSH); glutathione S-transferases (GST) and malondialdehyde (MDA) were determined in serum (spectrophotometry). Statistical analyses were performed using parametric and non-parametric tests. Multiple linear regression models and generalized additives models were also used to estimate the relationships between oxidative stress biomarkers and blood Hg. The juvenile riverine population from Cuniã RESEX presented the highest levels of oxidative stress and Hg levels in blood (GST = 27.2 (4.93) U/L, MDA = 1.69 (0.27) µmol/L, Hg = 20.6 (18.0) µg/L). This population also presented the highest frequency of fish consumption. The positive relation between Hg and GST and MDA, adjusted for individual characteristics, suggests an oxidative effect. This study shows the importance of oxidative stress biomarkers in the evaluation of dietary Hg exposure since initial and reversible metabolic changes were observed, enriching health risk assessments.

The role of chemical interactions between thorium, cerium, and lanthanum in lymphocyte toxicity.

Thorium, cerium, and lanthanum are metals present in several types of minerals, the most common of which is monazite. Cerium and lanthanum are elements in the lanthanides series. Thorium, an actinide metal, is a hazardous element due to its radioactive characteristics. There is a lack of information describing the possible chemical interactions among these elements and the effects they may have on humans. Toxicological analyses were performed using cell viability, cell death, and DNA damage assays. Chemical interactions were evaluated based on the Loewe additivity model. The results indicate that thorium and cerium individually have no toxic effects on lymphocytes. However, thorium associated with lanthanum increases the toxicity of this element, thereby reducing the viability of lymphocytes at low concentrations of metals in the mixture.

Dietary and reproductive determinants of plasma organochlorine levels in pregnant women in Rio de Janeiro.

Organochlorine (OC) plasma levels and their dietary and reproductive determinants were investigated in 64 pregnant women from Rio de Janeiro, Brazil. Prenatal exposure of newborns was evaluated in a subset of these women in which umbilical cord blood was analyzed. To assess the influence of dietary factors on OC levels, a semiquantitative food frequency questionnaire was completed by participants. Nondietary determinants were investigated through a general questionnaire that addressed reproductive history, lifestyle, and social-demographic characteristics. Both women and their newborns had detectable but low levels of OCs. The most frequently detected compound was p,p'-DDE, the main metabolite of p,p'-DDT. This compound was found in 97% of the women who participated in the study and in 67% of the umbilical cord blood samples, with levels ranging from 0.161 to 8.03ppb and from 0.320 to 1.06ppb, respectively. Among the OCs detected, only p,p'-DDE showed any correlation with dietary and nondietary factors. There was a positive correlation between maternal p,p'-DDE and the consumption of fish (Pearson r=0.38,P=0.002) and chicken (Pearson r=0.26, P=0.042). The correlation between pork consumption and p,p'-DDE exhibited an inverse relationship (Pearson r=-0.25,P=0.052). Parity was the only nondietary factor that showed a significant correlation (Pearson r=-0.36,P=0.004). The main determinants of p,p'-DDE levels in this group of women were fish consumption and parity, together explaining 28% of the variance (P<001), in a multivariate model.