Mercury Exposure in Women of Reproductive Age in Rondônia State, Amazon Region, Brazil.

Environmental contamination by mercury (Hg) is a problem of global scale that affects human health. This study's aim was to evaluate Hg exposure among women of reproductive age residing in the Madeira River basin, in the State of Rondônia, Brazilian Amazon. This longitudinal cohort study used linear regression models to assess the effects on Hg levels of breastfeeding duration at 6 months, and of breastfeeding duration and number of new children at 2-year and 5-year. Breastfeeding duration was significantly associated with maternal Hg levels in all regression models (6 months, 2 years and 5 years) and no significant association was observed between the number of children and the change in maternal Hg levels in the 2-year and 5-year models. This longitudinal cohort study evaluated Hg levels and contributing factors among pregnant women from different communities (riverine, rural, mining and urban) in Rondônia, Amazon Region, for 5 years. A well-coordinated and designed national biomonitoring program is urgently needed to better understand the current situation of Hg levels in Brazil and the Amazon.

Intestinal Parasites, Anemia and Nutritional Status in Young Children from Transitioning Western Amazon.

Young children are particularly vulnerable to the chronic sequelae of anemia, including poor nutritional status. The aim of this study was to assess intestinal parasitic-infections and nutritional status (anemia and linear growth) in preschool children living in contemporary Amazonian communities. A cross-sectional study measured children's intestinal parasites and hair-Hg (HHg)-biomarkers of fish consumption, hemoglobin levels, and growth (anthropometric Z-scores). Children came from traditional-living families (Itapuã), and tin-mining settlements (Bom Futuro) representing current transitioning populations. It covered 937 pre-school children (from 1 to 59 months of age) from traditional (247) and immigrant tin-mining families (688). There was a high prevalence of intestinal polyparasitic-infection in children from both communities, but mild anemia (hemoglobin concentrations) and moderate (chronic) malnutrition were more frequent in children from traditional families than in children from tin-mining settlers. Children from traditional families ate significantly more fish (HHg mean of 4.3 µg/g) than children from tin-mining families (HHg mean of 2.3 µg/g). Among traditional villagers, children showed a significant correlation (r = 0.2318; p = 0.0005) between hemoglobin concentrations and HHg concentrations. High rates of parasitic infection underlie the poverty and attendant health issues of young children in the Brazilian Amazon. The intestinal parasite burden affecting poor Amazonian children resulting from unsafe water, lack of sanitation and poor hygiene is the most urgent environmental health issue.

Data relating to maternal fish consumption, methylmercury exposure, and early child neurodevelopment in the traditional living of Western Amazonians.

This data paper includes information of a cohort organized to study the health, nutrition, and development of Amazonian children [1]. Child development were evaluated by trained nurses and psychologists with the Bayley Scales of Infant Development (at 24 months), the Stanford-Binet Intelligence Scale (at 60 months) and also with questionnaires administered by trained interviewers to the mothers. Maternal food questionnaires were used to estimate fish consumption and the associations between levels of prenatal and postnatal hair mercury (from mothers and children) and scores of neurodevelopment.

Influence of Maternal Fish Intake on the Anthropometric Indices of Children in the Western Amazon.

We studied trends in fish intake among pregnant women living in the Madeira River Basin in Rondônia State, Brazil, to investigate the influence of maternal fish intake on anthropometric indices of children followed up to 5 years. Maternal fish intake was assessed using hair mercury concentrations of mothers and children at delivery and 6, 24, and 59 months. Data analysis was performed using a linear mixed-effect model. Mothers were predominantly young, had low incomes and limited schooling, and breastfed for >6 months. Only 1.9% of children had low birth weight. Anthropometric indices in approximately 80% of the study population showed Z-score values ranging from ≥-2 to ≤1. The influence of maternal fish intake on anthropometric indices, including height-to-age (H/A), weight-to-age (W/A), and weight-to-height (W/H) were not statistically significant after model adjustments. However, higher income and larger birth weight had a positive influence on H/A and W/A, whereas W/H gain was favored by higher maternal educational status and breastfeeding duration. Other variables (hemoglobin concentration and maternal age) had a positive significant influence on anthropometric indices. Maternal fish intake (or its attendant MeHg exposure) did not affect children growth. Nevertheless, it is advisable to avoid mercury-contaminated fish during pregnancy and childhood.

Respiratory Condition of Family Farmers Exposed to Pesticides in the State of Rio de Janeiro, Brazil.

Pesticide exposure is a growing public health concern. Although Brazil is the world’s largest consumer of pesticides, only a few studies have addressed the health effects among farmers. This study aimed to evaluate whether pesticide exposure is associated with respiratory outcomes among rural workers and relatives in Brazil during the crop and off-seasons. Family farmers (82) were interviewed about occupational history and respiratory symptoms, and cholinesterase tests were conducted in the crop-season. Spirometry was performed during the crop and off-season. Respiratory outcomes were compared between seasons and multiple regressions analysis were conducted to search for associations with exposure indicators. Participants were occupationally and environmentally exposed to multiple pesticides from an early age. During the crop and off-season, respectively, they presented a prevalence of 40% and 30.7% for cough, 30.7% and 24% for nasal allergies, and 24% and 17.3% for chest tightness. Significant associations between spirometry impairments and exposure indicators were found both during the crop and off-season. These findings provide complementary evidence about the association of pesticide exposure with adverse respiratory effects among family farmers in Brazil. This situation requires special attention as it may increase the risk of pulmonary dysfunctions, and the morbidity and mortality burden associated with these diseases.

Child Nutritional Status in the Changing Socioeconomic Region of the Northern Amazon, Brazil.

The living conditions (i.e., socioeconomic, healthcare-related, nutritional, and environmental) to which children are exposed may influence their ability to reach their optimal growth potential. This review focuses on the relationship between the nutritional status of children under five years of age and social and environmental factors in Northern Brazil. Children living in this region have limited access to healthcare and face precarious socioeconomic and environmental conditions. This analysis was based on data from national health surveys, the consolidated food, nutrition surveillance system (SISVAN), and indicators of the DPSEEA (driving force, pressure, state, exposures, health effects, and actions) framework. The northern region has the worst living conditions in the country, and children under five years of age have significant height-for-age, weight-for-age, and weight-for-height deficits. Concomitantly, the prevalence of children who are overweight has increased significantly, although it remains lower than that in more developed Brazilian regions. Insufficient and/or inadequate dietary practices and early exposure to unfavorable living conditions are risk factors for nutritional deviations. Further advances in public health policies that consider regional characteristics, particularly in the north, where progress has been slower, are needed.

Impact of organic mercury exposure and home delivery on neurodevelopment of Amazonian children.

In the transitioning Amazon, we addressed birth environment (home vs hospital) and associated perinatal organic-Hg exposures: methylmercury (MeHg) from maternal fish consumption and ethylmercury (EtHg) from pediatric Thimerosal-containing vaccines (TCVs) taken systematically during hospital delivery. We studied 365 children in relation to linear growth at 60 months and neurodevelopment (milestone achievements, Bayley Scale of Infant Development/BSID at 24 months, and Stanford-Binet intelligence tests at 60 months). Mothers delivered in hospitals vs those gave birth at home had significantly (p<0.0001) lower hair-Hg (HHg) concentrations (12.2 vs 23.9µg/g respectively) and shorter length of breastfeeding (8.5 vs 9.7 months respectively). Home-born children had significantly (p<0.0001) higher HHg (7.1µg/g) than hospital-born children (4.6µg/g). Hospital-born children also had significantly earlier (p<0.0001) hepatitis B vaccine than home-born children (1.5 vs 24.1days respectively) and higher (p<0.0001) exposures to total TCV-EtHg (75.8 vs 49.3µg respectively). Neither anthropometric indices nor neurodevelopment (except for fluid reasoning) were directly affected by birth environment. The percentage of hospital-born children with BSID (MDI or PDI) scores <80 was not significantly different from those born at home. In spite of the differences in HHg and EtHg levels between hospital-born and home-born children, no impact on neurodevelopment was observed.

Traditional living in the Amazon: Extended breastfeeding, fish consumption, mercury exposure and neurodevelopment.

BACKGROUND: Features of traditional living in the Amazon Basin (high fish consumption and long breastfeeding) are likely to expose children to Mercury (Hg). AIM: To study neurodevelopment in 690 children in relation to prolonged breastfeeding and mercury exposure. SUBJECTS AND METHODS: Three groups of breastfeeding children were formed: Group 1 (breastfed for 6 months), Group 2 (7-12 months) and Group 3 (extending up to 24 months). Neurodevelopment was assessed as age of walking, age of talking and the Bayley Scales of Infant Development-BSID. Mercury exposure was assessed from Thimerosal-containing vaccines and fish consumption from hair Hg (HHg). RESULTS AND CONCLUSIONS: HHg increased in children and decreased in mothers at 24 months. Frequency of fish consumption was significantly correlated with maternal HHg at birth (Spearman's r = 0.8583; p = 0.0001); likewise, there was a significant correlation between duration of breastfeeding and children's HHg (Spearman's r = 0.15; p = 0.0018). Extended breastfeeding did not influence the Mental Development Index-MDI or Psychomotor Development Index-PDI, but maternal education and HHg (marker of fish consumption) interacted positively and significantly with both. Frequency of maternal fish consumption and education had a positive association with BSID scores; it is speculated that maternal education and nutrients in fish have an opposing effect on Hg exposure.

Mercury levels and human health in the Amazon Basin.

CONTEXT: Environmental mercury in the Amazon mostly originates from geochemical sources with some from artisanal gold mining (AGM). Geochemical-originated methylmercury (MeHg) reaches the aquatic food chain, ending up in fish. Inorganic Hg used in AGM is responsible for localised environmental contamination and occupational exposure of adults. In addition to this, iatrogenic ethylmercury (EtHg) derived from Thimerosal-containing vaccines (TCVs) exposes immunised infants. OBJECTIVE: To understand Hg exposure in the Amazon in relation to environmental fish-MeHg exposure, occupational AGM activities and low-doses of TCV-EtHg. METHODS: Medline and Thomson-Reuter Web of Science were searched to retrieve and select papers addressing Hg exposure and human health. RESULTS AND CONCLUSION: Environmental-Hg studies addressed health effects associated with birth weight, infant linear growth and neurodevelopment, while, in adults, environmental and occupational studies addressed immune and neurological issues. No widespread clinical toxicity was reported due to fish-MeHg. However, mixed results associated with Hg exposure can be found. Reducing children's exposure to EtHg is possible using Thimerosal-free vaccines, but it is difficult to interfere with fish consumption without consequences to riverine subsistence populations. Policies to diminish Hg exposure should focus on controlling and/or curbing widespread use of Hg (in gold amalgamation) and promotion of Thimerosal-free vaccines for pregnant women and young children.

Neurodevelopment of Amazonian children exposed to ethylmercury (from Thimerosal in vaccines) and methylmercury (from fish).

Few studies have addressed co-occurring methylmercury (MeHg) from maternal origin and ethylmercury (EtHg) from Thimerosal-containing vaccines (TCVs) during infant's neurodevelopment. We studied children (n=1139) from the Western Amazon based on combined (low, intermediate, and high) exposure to chronic MeHg from fish consumption and acute TCV- EtHg. Neurodevelopment outcomes were age of walking and age of talking, and the Bayley Scale of Infant Development (BSID). The Mental Developmental Index (MDI) and Psychomotor Developmental Index (PDI) were measured at six and 24 months of age. Median hair-Hg (HHg) at birth was 6.4µgg(-1) in mothers, and 1.94µgg(-1) in newborns; total (pregnancy and infancy) EtHg exposure ranged from 0 to 187.5µg. The combined (MeHg+EtHg) exposure showed significant differences for MDI but not for PDI; however, there was a significant decrease in both MDI and PDI scores at 24 months. The increase in BSID delays (scores <80) between six and 24 months was not discernible with regards to EtHg or MeHg exposure. We found a statistically significant increase in neurodevelopmental (BSID) delays related to the combined exposure to Hg (MeHg>EtHg). Neurodevelopment delays due to low-doses of organic mercury (albeit undiscernible) are not predictable but can be avoided by choosing low-Hg fish and providing Thimerosal-free vaccines.

Neurodevelopment outcomes in children exposed to organic mercury from multiple sources in a tin-ore mine environment in Brazil.

Methylmercury (from fresh-water fish) and ethylmercury [from thimerosal-containing vaccines (TCVs)] are the most prevalent source of neurotoxic exposure during early life in families consuming fish and using these vaccines. But children living in Amazonian mining environments are exposed to additional toxic metals in waste materials. We studied mercury (Hg) exposure and neurodevelopment in 294 children (105 boys and 189 girls) from Bom Futuro (Rondonia, Brazil), the epicenter of a tin-ore open-pit mine. Hair-Hg (HHg) concentrations and total ethylmercury (from TCVs) were taken from infants and respective mothers during pregnancy. We used bivariate analysis to determine the effect of sex and linear mixed models to assess the association of prenatal and postnatal organic Hg exposures with children's Bayley Scales of Infant Development (BSID) as psychomotor developmental index and mental developmental index (MDI) at 6 and 24 months of age as well as milestones achievements (age of walking and age of talking). Significant differences between boys and girls were observed for both MDI score (p = 0.0073) and MDI score (p = 0.0288) at 6 months but not at 24 months. Regression analysis showed that only in boys was there a significant interaction between MDI score with family income (ß = 0.288, p = 0.018) and with birth weight (ß = -0.216, p = 0.036) at 6 months; at 24 months, however, only boys showed a significant association of both MDI score (ß = -0.222, p = 0.045) and MDI score (ß = -0.222, p = 0.045) with neonatal HHg. In boys, age of walking was associated with HHg (ß = 0.188, p = 0.019) and breastfeeding (ß = -0.282, p = 0.000), whereas for girls, age of walking was only associated with breastfeeding (ß = -0.275, p = 0.001). In this mining environment, with only a weak association for prenatal Hg exposure, there was a significant sex difference in neurodevelopment, with boys showing more sensitivity related to BSID delays.

Perinatal multiple exposure to neurotoxic (lead, methylmercury, ethylmercury, and aluminum) substances and neurodevelopment at six and 24 months of age.

We studied neurodevelopment in infants from two communities. Children living in the vicinity of tin-ore kilns and smelters - TOKS; n = 51) were compared to children from a fishing village (Itapuã; n = 45). Mean hair-Hg (HHg) concentrations were significantly higher in Itapuã children which received significantly (p = 0.0000001) less mean ethylmercury (88.6 µg) from Thimerosal-containing vaccines (TCV) than the TOKS children (120 µg). Breast-milk Pb concentrations were significantly higher in the TOKS mothers (p = 0.000017; 10.04 vs. 3.9 µg L(-1)). Bayley mental development index (MDI) and psychomotor development index (PDI) were statistically significant (respectively p < 0.0000001, p = 0.000007) lower for the TOKS children only at 24 months of age. Multivariate regression analysis showed that MDI was negatively affected by breast-milk Pb and by HHg. PDI was positively affected by breastfeeding and negatively affected by ethylmercury. Milestone achievements were negatively affected by breast-milk Pb (age of walking) and by HHg (age of talking).

Milestone achievement and neurodevelopment of rural Amazonian toddlers (12 to 24 months) with different methylmercury and ethylmercury exposure.

Neurological outcomes (Gesell development schedules [GDS]), age of walking, and age of talking were studied in 299 toddlers (12 to 24 mo) in relation to environmental (fish consumption and tin mining) exposure. Exposure to fish methylmercury (MeHg) consumption and iatrogenic ethylmercury (EtHg) in Thimerosal-containing vaccines (TCV) was quantified in toddlers from two rural villages (n = 91, Itapuã; n = 218, Bom Futuro) respectively populated by fishers and cassiterite miners. Median total hair Hg (HHg) concentrations of infants from Itapuã (3.5 µg/g) were significantly higher than those of infants from Bom Futuro (2.2 µg/g). Median EtHg exposure from TCV was also significantly higher in toddlers from Itapuã (137.5 µg) than in those from Bom Futuro (112.5 µg). There were no significant differences between groups for any of the Gesell schedules; however, there were proportionally more compromised toddlers (GDS < 70) in Itapuã than Bom Futuro. Median age of talking was not statistically different but median age of walking was significantly higher in Bom Futuro. In toddlers from both villages, of fishers and miners, HHg concentrations were significantly correlated with family fish consumption. A logistic regression model was applied to all infants after classification into two groups: above or below the median Gesell schedules. Overall, there was no distinctive pattern of neurodevelopment associated with either HHg or EtHg exposure; however, nutritional status was significantly associated with GDS. In conclusion, milestone achievement was delayed in toddlers from tin-ore mining communities. Despite significantly higher exposure to both forms of organic Hg (MeHg from maternal fish consumption, and EtHg from TCV) in toddlers from the fishing village, significant differences were seen only among the proportions of most severely affected toddlers (GDS < 70).

Distribution of aluminum in hair of Brazilian infants and correlation to aluminum-adjuvanted vaccine exposure.

BACKGROUND: Nursing children are exposed to dietary aluminum (in breast milk and/or infant formulas) and through aluminum-adjuvanted vaccines (AAVs). We studied total hair-Al concentrations of nursing children that had been immunized with hepatitis B, DTP, and meningococcal vaccines. METHODS: We studied the hair of 37 young children (aged 26 to 824 days) who were exposed to cumulative doses of Al ranging from 0.63 to 6.88 mg from AAVs. Graphite furnace atomic absorption spectrometry was used to reliably measure total Al concentrations in hair samples. RESULTS: The analytical method proved sensitive enough to quantify Al in the hair of nursing children. At current levels of exposure it is possible to determine total Al in hair sample of 1.65 mg. Cumulative doses of AAV in children ranged from 0.63 to 6.88 mg Al. Median hair-Al was 47.7 µg g⁻¹ (ranging from 12.2 to 221.9 µg g⁻¹). There was no statistically significant correlation between hair-Al concentration and age of child (r=-0.049; p=0.774), total exposure from vaccine (r=-0.078; p=0.643), or the time elapsed after the last AAVs (r=0.015; p=0.931). CONCLUSION: Aluminum in children's hair can be reliably measured but we are still uncertain how representative it can be of the Al body burden.

Breast milk lead concentrations of mothers living near tin smelters.

We compared Pb concentration in human milk from 37 mothers living in a neighborhood of tin-ore smelters to that from 45 mothers living in a fishing community. The median breast-milk-Pb (BM-Pb) concentration was significantly (p = 0.0000001) higher (11.3 µg L(-1); ≤0.96-29.4 µg L(-1)) in mothers living in the vicinity of smelters than that of rural mothers (1.9 µg L(-1); ≤0.96-20.0 µg L(-1)). These mothers also showed a statistically significant correlation between length of residence and BM-Pb concentration (Spearman r = 0.6864; p < 0.0001). The estimated median exposure (for infants <6 months) was 3.0 µg kg(-1) b.w. for rural infants compared to 7.5 µg kg(-1) b.w. for infants in the vicinity of metal smelters. Overall, most BM-Pb concentrations (79 %) in the metal smelter area were above the critical limit of 5.0 µg L(-1) set by the WHO.

Mercury transfer during pregnancy and breastfeeding: hair mercury concentrations as biomarker.

UNLABELLED: Hair mercury (HHg) concentration is a biomarker of exposure that is widely used to assess environmental contamination by fish methylmercury and neurodevelopment in children. In the Rio Madeira basin (Brazilian Amazon), total HHg concentrations in 649 mother-infant pairs were measured at birth (prenatal exposure) and after 6 months of exclusive breastfeeding; these mother-infant pairs were from high fish-eating communities (urban, n = 232; rural, n = 35; and Riverine, n = 262) and low fish-eating tin-miner settlers (n = 120). Differences in kinetics were seen between Hg exposure from fish consumption and environmental exposure to a tin-ore mining environment. Overall maternal HHg concentrations (at childbirth and after 6 months of lactation) were higher than those of infant HHg. However, the relative change in HHg after 6 months of lactation showed that mothers decreased HHg while infants increased HHg. The relative change showed a consistently higher increase for girls than boys with a statistical significance only in high fish-eating mothers. The correlation coefficients between maternal and newborn hair were high and statistically significant for mothers living in urban (r = 0.66, p < 0.001), rural (r = 0.89, p < 0.001), and Riverine (r = 0.89, p < 0.001) communities not for tin miner settlers (r = 0.07, p = 0.427). After 6 months of exclusive breastfeeding, correlation coefficients showed high correlation coefficients and statistical significance for all groups (urban, r = 0.73, p < 0.001; rural, r = 0.88, p < 0.001; Riverine, r = 0.91, p < 0.001) except for Tin miners (r = -0.07, p = 0.428). A linear model analysis was used to assess the longitudinal associations of maternal total HHg and total HHg at birth (0 days) and 6 months of age in exclusively breastfed infants. Regression analysis significantly predicted HHg in newborn from maternal HHg for high fish-eating maternal-infant pairs. CONCLUSION: The concentration of mercury accumulated in newborn tissues (in utero and during breastfeeding) relevant to both, maternal sources and infant exposure, can be reliably assessed from maternal hair.

Fish consumption during pregnancy, mercury transfer, and birth weight along the Madeira River Basin in Amazonia.

UNLABELLED: Birth weight can be a predictor of maternal health issues related to nutrition and environmental contaminants. Total hair mercury (HHg) concentration was studied as an indicator of both fish consumption and methylmercury exposure in mothers (and newborns) living in selected low income areas of the Madeira River basin, Amazonia, Brazil. This cohort study (n = 1,433) consisted of traditional riverines (n = 396), riverines who had moved to urban (n = 676) and rural (n = 67) settings, and tin miner settlers (n = 294). Median maternal HHg was significantly different (p = 0.00001) between riverine (12.1 µg·g-1), rural (7.82 µg·g-1), urban (5.4 µg·g-1), and tin miner (4.5 µg·g-1) groups studied. The same trend (of medians) was observed for newborns' HHg which also showed significant differences between riverine (3.0 µg·g-1), rural (2.0 µg·g-1), urban (1.5 µg·g-1), and tin miner (0.8 µg·g-1) groups. The correlation between maternal and newborn HHg was statistically significant in the riverine (r = 0.8952; p = 0.0001), urban (r = 0.6744; p = 0.0001), and rural (r = 0.8416; p = 0.0001) groups but not in the mother-infant pairs in the tin miner group (r = 0.0638; p = 0.2752). Birth weight was significantly different among groups but did not show a pattern consistent with that of fish consumption (and HHg). A multiple regression analysis showed that only family income and gestational age had a significant impact on birth weight. CONCLUSIONS: Maternal HHg is an important biomarker of maternal fish consumption and of methylmercury exposure during pregnancy. However, in these Amazonian groups, only maternal education and gestational age seemed to affect birth weight positively.

Vaccine adverse events reported during the first ten years (1998-2008) after introduction in the state of Rondonia, Brazil.

Despite good safety records, vaccines given to young children can cause adverse events. We investigated the reported adverse events following immunization (AEFI) of vaccines given to children of less than seven years of age during the first ten years (1998 to 2008) in the state of Rondonia, Brazil. We worked with the events related to BCG (Bacillus Calmett-Guérin), HB (hepatitis B), DTwP/Hib (diphtheria-tetanus-pertussis+Hemophillus influenza b), DTP (diphtheria-tetanus-pertussis), MMR (mumps, measles, rubella), and YF (yellow fever) vaccines because they were part of the recommended scheme. The number of doses of vaccines given was 3,231,567 with an average of AEFI of 57.2/year during the studied period. DTwP/Hib was responsible for 298 (57.8%), DTP 114 (22.9%), HB 31 (6%), MMR 28 (5.4%), BCG 24 (4.7%), and YF 20 (3.9%) of the reported AEFI. The combination of the AEFI for DTwP/Hib vaccines showed the highest number of systemic (61.4%) and local events (33.8%). Young children (≤1-year old) were more susceptible to AEFI occurring in the 6 hours (54.2%) following vaccine uptake. This study suggests significant differences in reactogenicity of vaccines and that despite limitations of the AEFI Brazilian registry system we cannot ignore underreporting and should use the system to expand our understanding of adverse events and effects.

Neurodevelopment of Amazonian infants: antenatal and postnatal exposure to methyl- and ethylmercury.

Neurodevelopment as Gesell development scores (GDSs) in relation to mercury exposure in infants (<6 months of age) of one urban center and two rural villages, respectively, of fisherman and cassiterite miners. Mean total hair-Hg (HHg) concentrations of infants from Itapuã (3.95 ± 1.8 ppm) were statistically (P = 0.0001) different from those of infants from Porto Velho (3.84 ± 5.5 ppm) and Bom Futuro (1.85 ± 0.9 ppm). Differences in vaccine coverage among these populations resulted in significantly higher (P = 0.0001) mean ethylmercury (EtHg) exposure in urban infants (150 µg) than in infants from either village (41.67 µg, Itapuã; 42.39 µg, Bom Futuro). There was an inverse significant (Spearman r = -0.2300; P = 0.0376) correlation between HHg and GDS for infants from Porto Velho, but not for the rural infants from Bom Futuro (Spearman r = 0.1336; P = 0.0862) and Itapuã (Spearman r = 0.1666; P = 0.5182). Logistic regression applied to variables above or below the median GDS showed that EtHg exposure (estimated probability = -0.0157; P = 0.0070) and breastfeeding score (estimated probability = -0.0066; P = 0.0536) score were significantly associated with GDS. Conclusion. In nurslings whose mothers are exposed to different levels of fish-MeHg (HHg), a higher score of neurological development at six months was negatively associated with exposure to additional TCV-EtHg. Results should be interpreted with caution because of unaccounted variables.

Amazon forest fires between 2001 and 2006 and birth weight in Porto Velho.

Birth weight data (22,012 live-births) from a public hospital in Porto Velho (Amazon) was used in multiple statistical models to assess the effects of forest-fire smoke on human reproductive outcome. Mean birth weights for girls (3,139 g) and boys (3,393 g) were considered statistically different (p-value < 2.2e-16). Among all models analyzed, the means were considered statistically different only when treated as a function of month and year (p-value = 0.0989, girls and 0.0079, boys) . The R (2) statistics indicate that the regression models considered are able to explain 65 % (girls) and 54 % (boys) of the variation of the mean birth weight.