BackgroundChronic 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.AimOur 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.MethodsWe 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.ResultsArsenic concentrations in breast-milk samples were low (median, 1 μg/kg; range, 0.25–19 μg/kg), despite high arsenic exposures via drinking water (10–1,100 μg/L in urine and 2–40 μg/L in red blood cells). Accordingly, the arsenic concentrations in urine of infants whose mothers reported exclusive breast-feeding were low (median, 1.1 μg/L; range, 0.3–29 μg/L), whereas concentrations for those whose mothers reported partial breast-feeding ranged from 0.4 to 1,520 μg/L (median 1.9 μg/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.ConclusionVery 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.

11 12Environmental context. Marine mammals as top predators ingest a lot of arsenic from their food. In this 13 study liver samples and body fluids of marine mammals from the North and Baltic Seas were investigated 14 for arsenic speciation in order to get some information about their feeding habits. Only organic arsenic 15 compounds with low toxicity were detected in all investigated samples. Although a high quantitative 16 variability was observed, the same compounds were determined in all fluids examined. 18Abstract. The total arsenic concentrations in whole blood of harbor seals (Phoca vitulina) and in liver 19 tissues of harbor porpoises (Phocoena phocoena) were determined using TXRF (total-reflection X-ray 20 fluorescence spectrometry). The total arsenic concentration found in whole blood was lower for fish-fed ). In porpoise liver the arsenic concentrations were higher from carcases found in the North Sea (217- ). 25Furthermore the total arsenic content and arsenic species in urine, plasma, and gastric juice of seals and 26 the urine of porpoises, which were collected from animals at different areas in the North and Baltic Seas, 27were determined using ICPMS (inductively coupled plasma mass spectrometry . The arsenic is almost entirely present in inorganic forms.[1] 49Marine organisms are known to accumulate and convert inorganic arsenic to organic arsenic compounds. 50Mammals such as porpoises and seals living in the marine environment and feeding exclusively on marine 51 organisms are in an exceptional position. As top predators they could accumulate arsenic due to their 52 position in the food web. Goessler et al., reported in 1997 the arsenic concentrations and speciation in a 53 three organism marine food chain starting with a seaweed followed by two gastropods. They showed that 54 arsenic was accumulated and metabolized within this food chain.[2] These results were in contrast to those 55of Kubota et al., who found lower arsenic concentrations in marine mammals (seals and porpoises) 56 compared to those of lower tropic level marine organisms from other studies.[3] Furthermore Kubota et al. 57investigated a possible correlation between arsenic accumulation and gender, age (or body length), or 58 feeding habits in liver tissues of 16 different marine mammal species. The determined arsenic 59concentrations varied widely among species and individuals ranging from 100 to 7680 µg kg -1 dry mass. 60Marine mammals feeding on fish contained lower arsenic concentrations compared to animals feeding on 61cephalopods and crustaceans but no trend with gender or age could be seen.[3] 62Seals feed with regional and seasonal variations on fish, crustaceans, and cephalopods, [4] in contrast to 63 harbor porpoises, which feed mainly on fish and less frequently on molluscs and squids.[5] 64Arsenic contents in tissues of field-collected marine mammals, fish, and invertebrates have been reported 65 in quantities ranges from less than 1000 up to 30000 µg As kg -1 dry mass. [6][7] Total arsenic content in 66 whole blood of...