Effect of ascorbic acid on biotransformation and modification of the toxicity of mercurials in goldfish (Carassius auratus)

Epidemiologic confirmation that fruit consumption influences mercury exposure in riparian communities in the Brazilian Amazon

Since deforestation has recently been associated with increased mercury load in the Amazon, the problem of mercury exposure is now much more widespread than initially thought. A previous exploratory study suggested that fruit consumption may reduce mercury exposure. The objectives of the study were to determine the effects of fruit consumption on the relation between fish consumption and bioindicators of mercury (Hg) exposure in Amazonian fish-eating communities. A cross-sectional dietary survey based on a 7-day recall of fish and fruit consumption frequency was conducted within 13 riparian communities from the Tapajós River, Brazilian Amazon. Hair samples were collected from 449 persons, and blood samples were collected from a subset of 225, for total and inorganic mercury determination by atomic absorption spectrometry. On average, participants consumed 6.6 fish meals/week and ate 11 fruits/week. The average blood Hg (BHg) was 57.1 +/- 36.3 microg/L (median: 55.1 microg/L), and the average hair-Hg (HHg) was 16.8 +/- 10.3 microg/g (median: 15.7 microg/g). There was a positive relation between fish consumption and BHg (r = 0.48; P<0.0001), as well as HHg (r =0.34; P<0.0001). Both fish and fruit consumption entered significantly in multivariate models explaining BHg (fish: beta = 5.6, P<0.0001; fruit: beta = -0.5, P = 0.0011; adjusted model R2 = 36.0%) and HHg levels (fish: beta = 1.2, P<0.0001; fruit: beta = -0.2, P = 0.0002; adjusted model R2 = 21.0%). ANCOVA models showed that for the same number of fish meals, persons consuming fruits more frequently had significantly lower blood and HHg concentrations. For low fruit consumers, each fish meal contributed 9.8 microg/L Hg increase in blood compared to only 3.3 microg/L Hg increase for the high fruit consumers. In conclusion, fruit consumption may provide a protective effect for Hg exposure in Amazonian riparians. Prevention strategies that seek to maintain fish consumption while reducing Hg exposure in fish-eating communities should be pursued.

The influence of nutrition on methyl mercury intoxication

This article reviews progress in the research of methyl mercury (MeHg) and nutrient interactions during the past two decades. Special emphasis is placed on the following three major areas: a) effects on kinetics, b) effects on toxicity, and c) possible mechanisms. Dietary information is not usually collected in most epidemiologic studies examining of the effects of MeHg exposure. However, inconsistency of the MeHg toxicity observed in different populations is commonly attributed to possible effects of dietary modulation. Even though the mechanisms of interaction have not been totally elucidated, research in nutritional toxicology has provided insights into the understanding of the effects of nutrients on MeHg toxicity. Some of this information can be readily incorporated into the risk assessment of MeHg in the diets of fish-eating populations. It is also clear that there is a need for more studies designed specifically to address the role of nutrition in the metabolism and detoxification of MeHg. It is also important to collect more detailed dietary information in future epidemiologic studies of MeHg exposure.

Biochemical basis of the toxicity of mercury

Evidence is presented to support the hypothesis that the toxicity of mercury is at least partly due to its combination with coenzyme A and resultant interference in CoASH functions.

[Transformation reactions of special metals in organisms and in the environment. 3. In vivo reactions between mercury II chloride and monomethyltin trichloride in rats]

Following the comments on the metabolism and the toxicity of methylmercury compounds as well as on the interaction with food components and a few environmental chemicals from literature study, the results of the in vivo experiments for examining the reaction between HgCl2 and CH3SnCl3 in the gastrointestinal tract and the subsequent distribution of the formed methylmercury are reported. The reaction between both of the substances proceeding in aqueous solution with immediate formation of methylmercury also leads in the intestinal tract very rapidly to the formation of methylmercury and its distribution into various organs. An increase in the relative weight of liver and kidneys was evident.