Mercury: Major issues in environmental health
- Univ. of Rochester School of Medicine, NY (United States)
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 higher 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, staxia, constriction of the visual fields, and hearing loss. The presented 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 development delays. Methylmercury is believed to inhibit those processes in the brain specially involved in development and growth such as neuronal cell division and migration. 78 refs., 8 figs.
- OSTI ID:
- 6755236
- Journal Information:
- Environmental Health Perspectives; (United States), Vol. 100; ISSN 0091-6765
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
59 BASIC BIOLOGICAL SCIENCES
BRAIN
DAMAGE
METHYLMERCURY
BIOLOGICAL ACCUMULATION
BIOLOGICAL PATHWAYS
ONTOGENESIS
CELL DIVISION
BLOOD-BRAIN BARRIER
DIET
ENVIRONMENTAL EXPOSURE PATHWAY
FOOD CHAINS
PRENATAL EXPOSURE
SEDIMENTS
TISSUE DISTRIBUTION
BODY
CENTRAL NERVOUS SYSTEM
DISTRIBUTION
NERVOUS SYSTEM
ORGANIC COMPOUNDS
ORGANIC MERCURY COMPOUNDS
ORGANS
560300* - Chemicals Metabolism & Toxicology
550200 - Biochemistry