The effect of various dietary fibres on tissue concentration and chemical form of mercury after methylmercury exposure in mice

Rowland, Ian; Mallett, A.K.; Flynn, J.; Hargreaves, Richard

doi:10.1007/bf00286730

Cited by 75 publications

(42 citation statements)

References 24 publications

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“…Accordingly, earlier studies have demonstrated identical halftimes of methylmercury in mice exposed intraperitoneally and in mice fed a diet with CH 3 HgCI added (Clarkson, 1972). However, the available information on intestinal uptake of orally administered methylmercury in experimental animals is limited, and divergent figures for the wholebody retention of mercury at similar periods after dosage to mice have appeared (Clarkson, 1972;Landry et al, 1979;Mehra and Kanwar, 1980;Rowland et al, 1986). Furthermore, differences between retention of orally and intraperitoneally administered methylmercury have been reported (Mehra and Kanwar, 1980).…”

Section: Toxicokinetics Of Methylmercury In Experimental Animalsmentioning

confidence: 88%

Toxicokinetics of mercuric chloride and methylmercuric chloride in mice

Nielsen

1992

Journal of Toxicology and Environmental Health

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Future human exposure to inorganic mercury will probably lead to a few individuals occupationally exposed to high levels and much larger populations exposed to low or very low levels from dental fillings or from food items containing inorganic mercury; human exposure to methylmercury will be relatively low and depending on intake of marine food. Ideally, risk assessment is based on detailed knowledge of relations between external and internal dose, organ levels, and their relation to toxic symptoms. However, human data on these toxicokinetic parameters originate mainly from individuals or smaller populations accidentally exposed for shorter periods to relatively high mercury levels, but with unknown total body burden. Thus, assessment of risk associated with exposure to low levels of mercury will largely depend on data from animal experiments. Previous investigations of the toxicokinetics of mercuric compounds almost exclusively employed parenteral administration of relatively high doses of soluble mercuric salts. However, human exposure is primarily pulmonary or oral and at low doses. The present study validates an experimental model for investigating the toxicokinetics of orally administered mercuric chloride and methylmercuric chloride in mice. Major findings using this model are discussed in relation to previous knowledge. The toxicokinetics of inorganic mercury in mice depend on dose size, administration route, and sex, whereas the mouse strain used is less important. The "true absorption" of a single oral dose of HgCl2 was calculated to be about 20% at two different dose levels. Earlier studies that did not take into account the possible excretion of absorbed mercury and intestinal reabsorption during the experimental period report 7-10% intestinal uptake. The higher excretion rates observed after oral than after intraperitoneal administration of HgCl2 are most likely due to differences in disposition of systemically delivered and retained mercury. After methylmercury administration, mercury excretion followed first-order kinetics for 2 wk, independently of administration route, strain, or sex. However, during longer experimental periods, the increasing relative carcass retention (slower rate of excretion) caused the elimination to deviate from first-order kinetics. Extensive differences in the toxicokinetics of methylmercury with respect to excretion rates, organ deposition, and blood levels were observed between males and females.(ABSTRACT TRUNCATED AT 400 WORDS)

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Section: Toxicokinetics Of Methylmercury In Experimental Animalsmentioning

confidence: 88%

Toxicokinetics of mercuric chloride and methylmercuric chloride in mice

Nielsen

1992

Journal of Toxicology and Environmental Health

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“…Diets are important modulators of MeHg absorption (Chapman and Chan, 2000). Mice fed a high fiber diet (as 30% wheat bran) accumulated less THg in the small intestine, brain and blood compared to mice fed fiber-free and low-fiber diets, and the authors attributed this to differences in the metabolic activity of gut microbiota (Rowland et al, 1986). Among Brazilian fishers, the strength of the relationship between average hair Hg levels and fish consumption was weaker for those consuming at least one piece of fruit per day, and the authors suggested this may be due to the soluble dietary fiber content or other prebiotic nutrients of fruits, which modified the absorption of MeHg from the gut (Passos et al, 2003, 2007).…”

Section: Comprehensive Inventory Of Rice Grain Thg and Mehg Concenmentioning

confidence: 99%

Rice methylmercury exposure and mitigation: A comprehensive review

Rothenberg

Windham‐Myers

Creswell

2014

Environmental Research

170

151

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Rice cultivation practices from field preparation to post-harvest transform rice paddies into hot spots for microbial mercury methylation, converting less-toxic inorganic mercury to more-toxic methylmercury, which is likely translocated to rice grain. This review includes 51 studies reporting rice total mercury and/or methylmercury concentrations, based on rice cultivated or purchased in 15 countries. Not surprisingly, both rice total mercury and methylmercury levels were significantly higher in polluted sites compared to non-polluted sites (Wilcoxon rank sum, p<0.001). However, rice percent methylmercury (of total mercury) did not differ statistically between polluted and non-polluted sites (Wilcoxon rank sum, p=0.35), suggesting comparable mercury methylation rates in paddy soil across these sites and/or similar accumulation of mercury species for these rice cultivars. Studies characterizing the effect of rice cultivation under more aerobic conditions were reviewed to determine the mitigation potential of this practice. Rice management practices utilizing alternating wetting and drying (instead of continuous flooding) caused soil methylmercury levels to spike, resulting in a strong methylmercury pulse after fields were dried and reflooded; however, it is uncertain whether this led to increased translocation of methylmercury from paddy soil to rice grain. Due to the potential health risks, it is advisable to investigate this issue further, and to develop separate water management strategies for mercury polluted and non-polluted sites, which minimize methylmercury exposure through rice ingestion.

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“…The ability of pectin to reduce absorption and the bioaccumulation of toxic metals is attributed to pectin binding the metals in the digestive tract and preventing their absorption while facilitating their elimination in the feces. This may also include metals that have been absorbed previously and have been excreted into the bile or undergone enterohepatic circulation (Niculescu et al, 1969;Rowland et al, 1986).…”

Section: Introductionmentioning

confidence: 98%

The effect of modified citrus pectin on urinary excretion of toxic elements

Eliaz¹,

Hotchkiss

Fishman

et al. 2006

Phytotherapy Research

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This study was undertaken to evaluate the effect of modified citrus pectin (MCP) on the urinary excretion of toxic elements in healthy individuals. MCP is a reduced molecular weight pectin (weight-average molar mass = 15,400) that is mostly linear homogalacturonan with a 3.8% degree of esterification and approximately 10% rhamnogalacturonan II based on the presence of 2-keto-3-deoxy-octonic acid. Subjects ingested 15 g of MCP (PectaSol, EcoNugenics Inc., Santa Rosa, California 95407) each day for 5 days and 20 g on day 6. Twenty-four hour urine samples were collected on day 1 and day 6 for comparison with baseline. The urine samples were analysed for toxic and essential elements. In the first 24 h of MCP administration the urinary excretion of arsenic increased significantly (130%, p < 0.05). On day 6, urinary excretion was increased significantly for cadmium (150%, p < 0.05). In addition, lead showed a dramatic increase in excretion (560%, p < 0.08). This pilot trial provides the first evidence that oral administration of MCP increases significantly the urinary excretion of toxic metals in subjects with a 'normal' body load of metals. It is suggested that systemic chelation of toxic metals by MCP may in part be attributable to the presence of rhamnogalacturonan II, which has been shown previously to chelate metals.

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The effect of various dietary fibres on tissue concentration and chemical form of mercury after methylmercury exposure in mice

Cited by 75 publications

References 24 publications

Toxicokinetics of mercuric chloride and methylmercuric chloride in mice

Toxicokinetics of mercuric chloride and methylmercuric chloride in mice

Rice methylmercury exposure and mitigation: A comprehensive review

The effect of modified citrus pectin on urinary excretion of toxic elements

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