Mercury

THE MAJOR CLINICAL TOXICOLOGY OF MERCURY*

Variable

Mercury Vapor

Inorganic Divalent Mercury

Methyl Mercury

Ethyl Mercury

Common Route of exposure

Inhalation

Oral

Oral (eating fish)

Parenteral (preservative in vaccines)

Principal Target Organ

Brain, peripheral nerves, kidneys

Kidney

Brain

Brain, kidney

LOCAL SYMPTOMS

6

6

6

6

Lung

Bronchitis, pneumonitis (>1,000 mcg/M³ air)

Digestive

tract

Metallic taste, stomatitis, gingivitis, increased salivation (>1,000 mcg/M³ air)

Metallic taste, stomatitis, gastroenteritis

Skin

Hives, blisters

SYSTEMIC SYMPTOMS

6

6

6

6

Kidney

Proteinuria

Proteinuria, tubular necrosis

Proteinuria

Nervous system

Peripheral neuropathy (>500 mcg/M³ air)

Painful, pink extremities (Acrodynia)

Painful, pink extremities (Acrodynia)

Brain

Irritability, tremor (>500 mcg/M³ air)

Abnormal sensations, Loss of balance, visual and hearing loss (>200 mcg/L blood)

Abnormal sensations, Loss of balance, visual and hearing loss

Half-time in the body without treatment

60 days

40 days

70 days

20 days^†

Treatment^§

DMSA by mouth

DMSA by mouth

DMSA by mouth, but chelators do not reverse damage^§

DMSA by mouth, but chelators do not reverse damage^§

* Data were adapted from Gossel and Bricker.(4)

Clinical manifestations vary with the degree and length of exposure. The values in parentheses are the approximate range of mercury concentration in air (expressed as micrograms per cubic meter) and in blood (expressed as micrograms per liter) associated with the onset of clinical signs and symptoms. Epidemiologic studies that did not use specific end points such as IQ score indicate a risk of adverse effects (approximately 5 percent) at lower concentrations (e.g., 25 to 50 µg of mercury vapor per cubic meter and 40 µg of methyl mercury per liter of blood are associated with an increased risk of prenatal damage to the developing central nervous system).(3,5) In general, the atmospheric concentration of mercury vapor equals the urinary concentration. The mean urinary concentration in the U.S. general population is 0.72 µg per liter (95 percent confidence interval, 0.6 to 0.8), and the mean blood concentration is 0.34 µg per liter (95 percent confidence interval, 0.3 to 0.4).(6) In Europe (7) and other parts of the world,(8) blood concentrations appear to be somewhat higher. The mean urinary concentrations increase according to the number of dental amalgam surfaces, and blood concentrations increase according to the level of fish consumption.(6) No reliable data are available on the concentration of inorganic divalent mercury associated with adverse effects.

† The half-life of ethyl mercury in blood is about 20 days in adults, but may be as short as 7 days in infants.

‡ Details of meso-2,3-dimercaptosuccinic acid (DMSA) treatment have been published. (9-11)

§ Chelators can remove methyl and ethyl mercury from the body; they cannot reverse damage that has already occured to the brain and central nervous system. They may, however, prevent further deterioration. (12)

references

1. Toxicological profile for mercury. Atlanta: Agency for Toxic Substances DiseaseRegistry, 1999.

2. Evaluation of certain food additives and contaminants: twenty-second report of the Joint FAO/WHO Expert Committee on Food Additives. World Health Organ Tech Rep Ser 1978;631:1-39.

3. Environmental Protection Agency. Reference dose for chronic oral exposure to methylmercury. Greenbelt, Md.: Integrated Risk Information System, 2001.

4. Gossel TA, Bricker JD. Principles of clinical toxicology. 2nd ed. New York: Raven Press, 1990.

5. Inorganic mercury. Vol. 118 of Environmental health criteria. Geneva: World Health Organization, 1991.

6. Second national report on human exposure to environmental chemicals. Atlanta: Centers for Disease Control and Prevention, 2003. (Accessed October 6, 2003, at http://www.cdc.gov/exposurereport/ )

7. Brune D, Nordberg GF, Vesterberg O, Gerhardsson L, Wester PO. A review of normal concentrations of mercury in human blood. Sci Total Environ 1991;100:235-82.

8. Methylmercury. Vol. 101 of Environmental health criteria. Geneva: World Health Organization, 1990.

9. Forman J, Moline J, Cernichiari E, et al. A cluster of pediatric metallic mercury exposure cases treated with meso-2,3-dimercaptosuccinic acid (DMSA). Environ Health Perspect 2000;108:575-7.

10. Bluhm RE, Bobbitt RG, Welch LW, et al. Elemental mercury vapour toxicity, treatment, and prognosis after acute, intensive exposure in chloralkali plant workers. I. History, neuropsychological findings and chelator effects. Hum Exp Toxicol 1992;11:201-10.

11. Nierenberg DW, Nordgren RE, Chang MB, et al. Delayed cerebellar disease and death after accidental exposure to dimethylmercury. N Engl J Med 1998;338:1672-6.

12. Pfab R, Muckter H, Roider G, Zilker T. Clinical course of severe poisoning with thiomersal. J Toxicol Clin Toxicol 1996;34:453- 60.

Click here for a more complete list of references

Variable	Mercury Vapor	Inorganic Divalent Mercury	Methyl Mercury	Ethyl Mercury
Common Route of exposure	Inhalation	Oral	Oral (eating fish)	Parenteral (preservative in vaccines)
Principal Target Organ	Brain, peripheral nerves, kidneys	Kidney	Brain	Brain, kidney
LOCAL SYMPTOMS	6	6	6	6
Lung	Bronchitis, pneumonitis (>1,000 mcg/M³ air)
Digestive tract	Metallic taste, stomatitis, gingivitis, increased salivation (>1,000 mcg/M³ air)	Metallic taste, stomatitis, gastroenteritis
Skin		Hives, blisters
SYSTEMIC SYMPTOMS	6	6	6	6
Kidney	Proteinuria	Proteinuria, tubular necrosis		Proteinuria
Nervous system	Peripheral neuropathy (>500 mcg/M³ air)	Painful, pink extremities (Acrodynia)		Painful, pink extremities (Acrodynia)
Brain	Irritability, tremor (>500 mcg/M³ air)		Abnormal sensations, Loss of balance, visual and hearing loss (>200 mcg/L blood)	Abnormal sensations, Loss of balance, visual and hearing loss
Half-time in the body without treatment	60 days	40 days	70 days	20 days^†
Treatment^§	DMSA by mouth	DMSA by mouth	DMSA by mouth, but chelators do not reverse damage^§	DMSA by mouth, but chelators do not reverse damage^§
* Data were adapted from Gossel and Bricker.(4) Clinical manifestations vary with the degree and length of exposure. The values in parentheses are the approximate range of mercury concentration in air (expressed as micrograms per cubic meter) and in blood (expressed as micrograms per liter) associated with the onset of clinical signs and symptoms. Epidemiologic studies that did not use specific end points such as IQ score indicate a risk of adverse effects (approximately 5 percent) at lower concentrations (e.g., 25 to 50 µg of mercury vapor per cubic meter and 40 µg of methyl mercury per liter of blood are associated with an increased risk of prenatal damage to the developing central nervous system).(3,5) In general, the atmospheric concentration of mercury vapor equals the urinary concentration. The mean urinary concentration in the U.S. general population is 0.72 µg per liter (95 percent confidence interval, 0.6 to 0.8), and the mean blood concentration is 0.34 µg per liter (95 percent confidence interval, 0.3 to 0.4).(6) In Europe (7) and other parts of the world,(8) blood concentrations appear to be somewhat higher. The mean urinary concentrations increase according to the number of dental amalgam surfaces, and blood concentrations increase according to the level of fish consumption.(6) No reliable data are available on the concentration of inorganic divalent mercury associated with adverse effects. † The half-life of ethyl mercury in blood is about 20 days in adults, but may be as short as 7 days in infants. ‡ Details of meso-2,3-dimercaptosuccinic acid (DMSA) treatment have been published. (9-11) § Chelators can remove methyl and ethyl mercury from the body; they cannot reverse damage that has already occured to the brain and central nervous system. They may, however, prevent further deterioration. (12) references 1. Toxicological profile for mercury. Atlanta: Agency for Toxic Substances DiseaseRegistry, 1999. 2. Evaluation of certain food additives and contaminants: twenty-second report of the Joint FAO/WHO Expert Committee on Food Additives. World Health Organ Tech Rep Ser 1978;631:1-39. 3. Environmental Protection Agency. Reference dose for chronic oral exposure to methylmercury. Greenbelt, Md.: Integrated Risk Information System, 2001. 4. Gossel TA, Bricker JD. Principles of clinical toxicology. 2nd ed. New York: Raven Press, 1990. 5. Inorganic mercury. Vol. 118 of Environmental health criteria. Geneva: World Health Organization, 1991. 6. Second national report on human exposure to environmental chemicals. Atlanta: Centers for Disease Control and Prevention, 2003. (Accessed October 6, 2003, at http://www.cdc.gov/exposurereport/ ) 7. Brune D, Nordberg GF, Vesterberg O, Gerhardsson L, Wester PO. A review of normal concentrations of mercury in human blood. Sci Total Environ 1991;100:235-82. 8. Methylmercury. Vol. 101 of Environmental health criteria. Geneva: World Health Organization, 1990. 9. Forman J, Moline J, Cernichiari E, et al. A cluster of pediatric metallic mercury exposure cases treated with meso-2,3-dimercaptosuccinic acid (DMSA). Environ Health Perspect 2000;108:575-7. 10. Bluhm RE, Bobbitt RG, Welch LW, et al. Elemental mercury vapour toxicity, treatment, and prognosis after acute, intensive exposure in chloralkali plant workers. I. History, neuropsychological findings and chelator effects. Hum Exp Toxicol 1992;11:201-10. 11. Nierenberg DW, Nordgren RE, Chang MB, et al. Delayed cerebellar disease and death after accidental exposure to dimethylmercury. N Engl J Med 1998;338:1672-6. 12. Pfab R, Muckter H, Roider G, Zilker T. Clinical course of severe poisoning with thiomersal. J Toxicol Clin Toxicol 1996;34:453- 60. Click here for a more complete list of references