Mercury chronic exposure

Thain, J.E. 1984. Effects of mercury on the prosobranch mollusc Crepidula fornicata acute lethal toxicity and effects on growth and reproduction of chronic exposure. Mar. Environ. Res. 12 285-309. 

Ingestion Toxicity Data are available for the acute (single-dose) ingestion/oral toxicity of many toxic materials (National Institute for Occupational Safety and Health, Registry of Toxic Effects of Chemical Substances, 1983 Lewis, Sax s Dangerous Properties of Industrial Materials, 9th ed., 1996). However, very few data are available for prolonged ingestion or periodic doses of toxic materials. It is likely that metabolic processes would operate to increase the total burden required for toxic effects for such chronic exposures, except for some materials (such as mercury and lead) which apparently can accumulate in the body. 

Immunosuppressive effects have been obtained in vitro with mercuric chloride. A marked inhibition of the mixed lymphocyte reaction in mice as well as PFC (plaque forming cell) response to SRBC (sheep red blood cells) by mercuric chloride [166] has been reported. Chronic exposure to mercury of rabbits gave immunosuppression, measured as low antibody titres to viral agents [167], A suppression of antibody production in chickens exposed to mercuric chloride has also been reported [168]. Furthermore, an inhibition of mitogenic response to PHA in lymphocytes by mercuric chloride has been obtained [169],... 

Toxicology. Acute exposure to high concentrations of mercury vapor causes severe respiratory damage, whereas chronic exposure to lower levels is primarily associated with central nervous system damage and renal effects. 

Renal damage has been reported after both acute and chronic exposure. Mercury is known to accumulate in the kidneys, and case studies have described increased creatinine excretion, proteinuria, hematuria, and degeneration of the convoluted tubules in exposed individuals. Increased levels of the urinary enzyme NAG (AT-acetyl-P-glycosaminidase), compared with controls, have been observed in chronically exposed workers. ... 

Methyl and ethyl mercury compounds have similar toxicological properties, and there is no sharp demarcation between acute and chronic poisoning. Once a toxic dose has been absorbed and retained for a period of time, functional disturbances and damage occur. The latency period for a single toxic dose may vary from one to several weeks longer latency periods on the order of years have been reported for chronic exposures. ... 

Mercury was used to cure the felt used in hats, and workers developed the characteristic signs of mercury vapor toxicity. Acute exposure to high concentrations of mercury vapor causes respiratory distress, which can be fatal. The symptoms of chronic exposure to mercury vapor include personality changes such as excitability, depression, memory loss, fine motor tremor that can become progressively worse, gingivitis, and hallucination. There is some mercury inhalation exposure from dental amalgam, but for most people there are no health-related effects. Metallic mercury is very poorly absorbed from the intestine, thus it is much better to swallow the mercury from a thermometer than inhale it (see chapter on mercury). 

Elemental Mercury Vapor. Although there may be toxic effects to the respiratory system from the inhalation of mercury vapor, the major toxic effect is to the CNS. This is especially true after chronic exposure. There are a variety of symptoms such as muscle tremors, personality changes, delirium, hallucination, and gingivitis. 

Chronic exposure its mercury vapor produces an insidious form ot toxicity that is manifested hy neurological effects and is referred to as the asthenic vegetative syndrome. 

Boisson, F., M.G.J. Hard, S.W. Fowler, and C. Amiard-Triquet. 1998. Influence of chronic exposure to silver and mercury in the field on the bioaccumulation potential of the bivalve Macoma balthica. Mar. Environ. Res. 45 325-340. 

The kidney is the primary target organ for Hg2+. Chronic exposure to inorganic mercury ) compounds causes proteinuria. In cases of mercury poisoning of any type, the kidney is the organ with the highest bioaccumulation of mercury. 

Heavy metals, like lead and mercury, have been recognized as toxic poisons for centuries. Further, toxic concentrations of mercury, for example, can trigger several effects like autoimmune diseases, infections, unexplained chronic fatigue, depression, nerve impairment, memory problems, decreased mental clarity, and bowel disorders. For several decades, mercury vapor exposure has caused severe health problems among chloralkali workers. This is only an example. It may be repeated that education can effectively minimize exposure to hazardous metals. Basic information and training for proper handling of toxic chemicals will reduce potential adverse health effects. 

R. Kishi, R. Doi, Y. Fukuchi, H. Satoh, T. Satoh, A. Ono, et al., Subjective symptoms and neurobehavioral performances of ex-mercury miners at an average of 18 years after the cessation of chronic exposure to mercury vapor. Environ. Res. 62 289, 1993. 

Thimerosal is also used as a preservative in some contact lens solutions. Sensitivity to thimerosal, and concerns about chronic exposure to mercury, have encouraged the development of thimerosal-free antiseptics and contact-lens solutions. 

Chronic toxicity studies provide information on the long-term health effects of chemical substances. Adverse health effects in exposed animals and subsequent severe damage are known to occur after repeated exposure to low doses over a period of time. The slow accumulation of mercury or lead in the body or after a long latency period from exposure to chemical carcinogens is an example. Chronic or prolonged periods of exposure to chemical substances may also cause adverse effects on the reproduction and behavior of animals and humans. The symptoms caused after chronic exposure usually differ from those observed in acute poisoning from the same chemical. In fact, when exposed to low concentrations of chemical substances, as is the case with chronic toxicity studies, the industrial worker and common public are unaware of the exposure. 

Chronic exposure to methyl mercury results in increased urinary excretion of uro- and coproporphyrins in rats, mediated via inhibition of ferrochelatase. Acute... 

Friberg L, Hammarstr6mS,Nystrdm A. Kidney injury after chronic exposure to inorganic mercury. Arch Ind HygOccupMed 1953 8 149-53. 

Observe normal precautions appropriate to the circumstances and quantity of material handled. Phenylmercuric acetate may be irritant to the skin, eyes, and mucous membranes. Eye protection, gloves, and a respirator are recommended. Chronic exposure via any route can lead to central nervous system damage. In the UK, the occupational exposure limit for mercury-containing compounds, calculated as mercury, is 0.01 mg/m long-term (8-hour TWA) and 0.03 mg/m shortterm. ... 

Similarly, in most studies, the simultaneous administration of mercury and selenium in equimolar doses to animals has resulted in decreased toxicity of both elements in acute and chronic exposure studies. 

Additional chronic-duration oral exposure information in animals concerning renal effects following inorganic mercury exposure is needed to evaluate the threshold of this effect in humans following chronic exposure. The data would be useful if populations living near hazardous waste sites were to be exposed chronically to inorganic mercury that leached into near-by wells or water supplies. 

Rowland, AS Chronic disease risks associated with mercury vapor exposure. NIEHS... 

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