Mercury, alkyl compounds

Synonyms

Synonyms vary depending upon the specific (organo) alkyl mercury compound. [NIOSH]

Category

Metals, Organic Compounds

Description

Appearance and odor vary depending upon the specific (organo) alkyl mercury compound. [NIOSH]

Sources/Uses

Used as preservatives (wood, paper & pulp, textiles, and leather) and fungicides (seed dressings and plant sprays); [ACGIH] Microorganisms in soil and water convert inorganic mercury into organic mercury. This occurred in Minimata Bay, Japan in 1953 when 111 people died or were severely injured after eating fish from the bay that had been polluted with mercury. Another disaster involving methyl mercury was in Iraq in 1971 after people ate treated grain. [Sullivan, p. 869] Gold refining by the amalgam process contaminates water, sediment, and plankton with mercury and can cause accumulation of methylmercury in fish. [Nordberg, p. 834]

Comments

Symptoms of organic mercury poisoning include paresthesias (numbness and tingling), ataxia, tremor, spasticity, vision and hearing loss, behavioral changes, and intellectual deterioration. [LaDou, p. 477] Alky mercury compounds are toxic to the kidneys and central and peripheral nervous systems. Methyl, ethyl, n-propyl, and n-butyl mercury compounds are potent neurotoxins that can easily pass through the skin, blood-brain barrier, and placenta. [ACGIH] Short-chained alkyl compounds include ethylmercury and methylmercury, and dimethylmercury. Methylmercury is produced by bacteria in the environment and bioconcentrated by predatory fish. Dimethylmercury, used as a special laboratory reagent, has caused delayed encephalopathy and death after absorption of a few drops through the skin. [Rom, p. 990-6] The classic adverse effects of methylmercury poisoning are dysarthria, ataxia, constricted visual fields, paresthesias, and hearing impairment. There is a latency of several weeks to months before onset of symptoms after exposure. Methylmercury is excreted in the feces, and urinary levels are not useful. The half-life of blood mercury is about 50 days. Blood mercury levels above 200 mcg/L have been associated with symptoms. In the 1999-2002 NHANES survey of US women age 16-49, the levels of whole-blood mercury were 0.92 mcg/dL (mean) and 6.04 mcg/L (95th percentile). [Olson, p. 272-3] Organic mercury compounds are reproductive toxins that can cause CNS malformations and cerebral palsy in humans. [ATSDR Case Studies # 29] "Mercurial diuretics, methoxyethyl mercury, ethyl mercury, and phenyl mercury compounds have caused renal toxicity, including nephrotic syndrome, albuminuria, and renal failure. An autoimmune response to a mercury-protein complex has been hypothesized." [Sullivan, p. 875] Danger of skin sensitization; [MAK] See "Mercury," "Mercury, aryl compounds," and "Mercury, inorganic compounds." See "ORGANOMETALS."

The EPA banned for pesticide use chloromethoxypropylmercuric acetate (CPMA); http://www.epa.gov/oppfead1/international/piclist.htm]

Biomedical References

Yes

Yes

0.01 mg/m3, as Hg

0.03 mg/m3, as Hg

0.01 mg/m3, as Hg, Ceiling(OSHA) = 0.04 mg/m3, as Hg

2 mg/m3, as Hg

Excerpts from Documentation for IDLHs

"Deaths have resulted from 3 months exposure to diethyl mercury at an estimated concentration of 1 mg/m3 [Hill 1943]. The lethal dose of methyl mercury is estimated to be 200 mg, with paresthesia of the hands, feet, and mouth occurring at a total body burden of 40 mg [Bakir et al. 1973]. [Note: An oral dose of 200 mg of methyl mercury is equivalent to a worker being exposed to about 125 mg Hg/m3 for 30 minutes, assuming a breathing rate of 50 liters per minute and 100% absorption.]" [NIOSH]

LC50 = 18-54 mg/m3;

Explanatory Notes

Exposure values are for "Mercury, alkyl compounds, as Hg."

Methyl mercury: 40-105 days; [ACGIH]

Yes

Other CNS neurotoxin

Yes

Yes

Possible (2b)

Diseases

Occupational diseases associated with exposure to this agent:

• Birth defects
• Contact dermatitis, allergic
• Encephalopathy, acute toxic

Processes

Industrial Processes with risk of exposure:

• Leather Tanning and Processing