Sexual differences in the distribution and retention of organic and inorganic mercury in methyl mercury-treated rats

Thomas, David J.; Fisher, Henry L.; Sumler, Martha R.; Marcus, Allan H.; Mushak, Paul; Hall, Larry L.

doi:10.1016/s0013-9351(86)80184-0

Cited by 56 publications

(30 citation statements)

References 18 publications

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“…Our studies also indicated a wide range ofhalf-time values from tless than 20 to more than 70 days (26). In fact, animal experiments indicated that sex, age, and genetics are important in determining individual differences in half-times (37)(38)(39)(40).…”

Section: Disposition Of Methylmercurysupporting

confidence: 57%

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Mercury: major issues in environmental health.

Clarkson

1993

Environ Health Perspect

456

185

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In the past, methylmercury compounds were manufactured as fungicides or appeared as unwanted byproducts of the chemical industry, but today the methylation of inorganic mercury in aquatic sediments and soils is the predominant if not the sole source of methylmercury. This form of mercury is bioaccumulated to a high degree in aquatic food chains to attain its highest concentrations in edible tissues in long-lived predatory fish living in both fresh and ocean waters. It is well absorbed from the diet and distributes within a few days to all tissues in the body. It crosses without hindrance the blood-brain and placental barriers to reach its principal target tissue, the brain. It is eliminated chiefly in the feces after conversion to inorganic mercury. The biological half-time of methylmercury in human tissues is about 50 days, but there is wide individual variation. Adult poisoning is characterized by focal damage to discrete anatomical areas of the brain such as the visual cortex and granule layer of the cerebellum. A latent period of weeks or months may ensue before the appearance of signs and symptoms of poisoning. The latter manifest themselves as paresthesia, ataxia, constriction of the visual fields, and hearing loss. The prenatal period is the most sensitive stage of the life cycle to methylmercury. Prenatally poisoned infants exhibit a range of effects from severe cerebral palsy to subtle developmental delays. Methylmercury is believed to inhibit those processes in the brain specially involved in development and growth such as neuronal cell division and migration.

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Section: Disposition Of Methylmercurysupporting

confidence: 57%

“…animals (37,38,41 (44) and microflora (45) influence methylmercury excretion in adult animals. The ligation of the common bile duet in rats caused a redistribution of methylmercury in the body (27).…”

Section: Disposition Of Methylmercurymentioning

confidence: 99%

Mercury: major issues in environmental health.

Clarkson

1993

Environ Health Perspect

456

185

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“…For example, the consumption of fibre, which may decrease MeHg absorption (28) , seemed to be higher among women, possibly explaining why some associations were observed only among men. Additionally, differences in the MeHg excretion and organ distribution between the sexes have been observed in the mouse, rat and man (44)(45)(46) . Specifically, males seem to be more effective in eliminating Hg compared with females, which may in part explain the differences in the observed associations between men and women.…”

Section: Discussionmentioning

confidence: 99%

Blood concentration of methylmercury in relation to food consumption

Airaksinen

Turunen

Rantakokko

et al. 2010

Public Health Nutr.

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Objective: Dietary fish is the main source of methylmercury (MeHg) for man, and fish consumption has been used as a measure of MeHg exposure. However, other dietary sources of exposure exist and MeHg metabolism may also be modified by nutritional factors. The aim of the present study was to examine the association between blood MeHg concentration and consumption of different foods in a Finnish population with high fish consumption. Design: Blood samples, a detailed FFQ and additional frequency data on fish consumption were collected. MeHg was analysed from whole blood by the isotope dilution method with high-resolution MS. The consumption of different foods was calculated by MeHg quartiles and tested for linear trend. Setting: Finnish southern and south-western coast of the Baltic Sea. Subjects: Two hundred and ninety-nine professional fishermen, their spouses and other family members. Results: Mean (range) blood MeHg concentration was 4?6 (0?21-22) mg/l among men and 2?8 (,0?15-20) mg/l among women. Fish had the strongest positive association with MeHg (P for linear trend ,0?001 among both men and women). Among men, positive associations were also observed for fruit vegetables, wheat and wine. Among women, positive associations were observed for root vegetables, legumes, potato and game, but adjustment for fish consumption attenuated these trends. Conclusions: The study shows that, besides fish, MeHg may have other dietary sources that should be taken into account in risk assessment studies. Due to the observed high blood MeHg concentration, a thorough exposure assessment among the general Finnish population is recommended.

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“…Sexual differences in whole-body clearance and tissue distribution of intestinally absorbed methylmercury have been demonstrated in rats, mice, and humans (Magos et al, 1981;Miettinen, 1973;Thomas et al, 1986;Yasutake and Hirayama, 1988). Furthermore, differences in wholebody retention between male and female mice depend on the mouse strain.…”

Section: !mentioning

confidence: 99%

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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Sexual differences in the distribution and retention of organic and inorganic mercury in methyl mercury-treated rats

Cited by 56 publications

References 18 publications

Mercury: major issues in environmental health.

Mercury: major issues in environmental health.

Blood concentration of methylmercury in relation to food consumption

Toxicokinetics of mercuric chloride and methylmercuric chloride in mice

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