Effects on Humans
How it works
Effects on Whole Body
Treatment Summary
Arsenic and Seafood Consumption
Arsenic in Asian Medications
Arsenic in Cigarettes
Arsenic-containing Pesticides in Malaysia
PRN Links

A. Description

  1. CAS# 7440-38-2
  2. Odourless, brittle, grey, metallic-looking crystals.
  3. Molecular formula: As
  4. Atomic weight: 74.92

B. Synonyms

Arsen; Arsenia; Arsenic-75; Arsenic Black; Arsenicals; Colloidal Arsenic; Gray Arsenic; Grey Arsenic; Metallic Arsenic

C. General (1)

  1. All soluble arsenic (As) compounds are considered to be poisonous to humans.

  2. The major sources of airborne arsenic emissions are the smelting of metals, burning of fossils fuels, and application of pesticides.

  3. Arsenic and its compounds are widely distributed in nature primarily in two oxidation states, arsenite (trivalent, 3+) and arsenate (pentavalent, 5+).
  4. Inorganic and organic arsenic compounds used as pesticides, plant defoliants, and herbicides may accumulate in agriculture and horticultural soils and plants (see Inorganic and Organic arsenic).

  5. Traces of arsenic are found in most foods, with the highest concentrations found in seafood, particularly shellfish (see F. Arsenic and Seafood Consumption)

  6. The levels of intoxication from arsenic depend upon one's age, state of health, nutritional status, possible accustomization, and the time-dose relationship.

  7. The normal body burden in adults is 0.01 - 0.46 mg/kg arsenic.

  8. The WHO Health Organization (WHO) recommends a tolerable daily intake of 0.05 mg As/kg bodyweight from food and no more than 20 g/L in the drinking water (WHO, 1983). The tolerable daily intake figure was developed to be applied to short term and chronic exposures and was not meant to be applied to incidences involving single daily exposures.
    In an updated issue of WHO bulletin (2), the present WHO drinking water guideline value for arsenic is 50 microgramme/litre.

  9. The provisional maximum tolerable weekly adult intake for organic arsenic recommended by the WHO/FAO (15 microgramme/kg/week) for short term or chronic exposures, this document recommends a tolerable daily intake of inorganic arsenic of 130 microgramme.

  10. The consumption of seafood, especially shrimp and lobster, may lead to increased arsenic ingestion; however, most of the arsenic compounds found in shrimp and lobster are methylated (detoxified arsenic), and therefore are relatively low in toxicity.

  11. Demethylated arsenic compounds, the most abundant form found in the environment, arises from the conversion of arsenic by microorganisms. This is predominant form which accumulates in fish.

  12. In humans, demethylated arsenic represents 75% of the total arsenic excreted; monomethylated arsenic being excreted in lesser amounts.

  13. Like inorganic arsenic, organoarsenic compounds in seafoods are readily absorbed (greater than 80%) from the gastrointestinal tract in animals and humans. However, more than 80% of the ingested arsenic-in-fish is excreted in human urine within a few days after ingestion.

Inorganic and Organic arsenic (1)

  1. Inorganic arsenic is more toxic than organic arsenic, and the inorganic arsenic poisoning usually occur from occupational exposure.

  2. Organic arsenic is excreted more rapidly than inorganic arsenic. Arsenic 5+ (arsenate) is excreted more rapidly than arsenic 3+ (arsenite).

  3. Nearly all of the arsenic found in seafood is organic arsenic which is considered to be much less toxic than inorganic arsenic.

  4. In humans, demethylated arsenic represents 75% of the total arsenic excreted; monomethylated arsenic compounds are excreted in lesser amounts.

  5. Epidemiological studies have demonstrated an evident of causal relationship between environmental, occupational, occupational, and medicinal exposure of humans to inorganic arsenic and cancer of the skin and lungs.

  6. Inorganic arsenic can have acute, subacute and chronic effects which may be either local or systemic.

D. Effects on Humans (2)

  1. In man, the smallest recorded fatal dose is in the range of 70-80 mg, but recovery has been reported after much larger doses. Acute symptoms develop within 30 munites to 2 hours, in the form of a sudden and explosive gastroenteritis.

  2. Severely poisoned patients develop shock as a result of increased permeability and loss of fluids and electrolytes. Death usually results from heart failure within 24 hours to 4 days.

  3. Tolerance to arsenic can develop after repeated exposure. The chronic signs of toxicity are insidious and may be difficult to diagnose. A major symptom of chronic poisoning by arsenic is a symmetrical hyperkeratosis of the palms and soles, as well as melanosis.

- short-term exposure (3):

1. The substance irritates the eyes, the skin and the respiratory tract. The substance may cause effects on the circulatory system, nervous system, kidneys and gastrointestinal tract, resulting in convulsions, kidney impairment, severe hemorrhage, losses of fluids, and electrolytes, shock and death. Exposure may result in death. The effects may be delayed. Medical observation is indicated.

- long-term exposure (3):

2. Repeated or prolonged contact with skin may cause dermatitis. Repeated or prolonged contact may cause skin sensitization. The substance may have effects on the mucous membranes, skin, kidneys, liver , resulting in neuropathy, pigmentation disorders, perforation of nasal septum and tissue lesions. This substance is carcinogenic to humans.

E. How it works (4)

  1. Arsenic is well absorbed by inhalation, ingestion and dermal exposure. It is initially bound to the protein portion of hemoglobin in the RBC and then is distributed to the liver, spleen, lungs, intestine, and skin over the first 24 hours.

  2. The toxic effects are mediated through the trivalent (arsenite) form. Penvalent [arsenate] forms are believed to be reduced to trivalent forms in vivo.

  3. The main mode of arsenic toxicity is inhibition of enzyme activity by binding to the sulfhydryl groups (-SH). It inhibits succinic dehydrogenase [enzyme] activity, uncoupling oxidative phosphorylation [reaction].

  4. Arsenic is also substituted for phosphorus in the oxidative phosphorylation chain, further increasing the loss of production of high-energy phosphate bonds in ATP, which causes widespread multisystem effects.

  5. Arsenic concentrates in hair, nails and skin within 2 weeks of exposure.

  6. When amounts below 200-250 microgramme per day are ingested, the body can detoxify arsenic by the addition of methyl groups (5).

F. Effects on Whole Body (6)

  1. A study report of medical and environmental surveys in arsenic affected areas in West Bengal by An Asian Arsenic Network, February 5-12, 1996.

  2. Hyperpigmentation cases in the West Bengal study.

G. Treatment Options and Summary (4)

  1. Gastric decontamination is indicated after acute ingestion. Gastric lavage, not induced emesis, is recommended.

  2. General supportive measures for treatment of arsenic poisoning include administration of isotonic intravenous fluids. Vasopressors such as dopamine and norepinephrine [noradrenaline] may be used but only after adequate hydration.

  3. Hemodialysis for acute arsenic exposures has produced unclear results. In the absence of renal failure it has not shown to be beneficial.

  4. Chelation is best accomplished with BAL (British anti-Lewisite).

    Indications for treatment include ingestions of unknown amounts.

  5. Penicillamine may be used with BAL.

  6. Dimercaptosuccinic acid (DMSA) is under investigation for use in chronic arsenic poisoning.

  7. Arsine gas* exposure is treated initially with removal of the patient from the contaminated environment and removal of all contaminated clothing. Exchange transfusion may be necessary.

  8. Most of the agents used for treatment are with adverse or rare side effects.

For details please contact Pusat Racun Negara

* Arsine gas is the most toxic form of arsenic

H. Arsenic and Seafood Consumption (7)

The determination of arsenite, arsenate, dimethylarsenic acid (DMA) and monomethylarsonic acid (MMA) in urine has been used for assessing occupational exposure to inorganic arsenic because these species were thought to be unaffected by dietary arsenic. However, this investigation reports how the consumption of certain types of seafood can lead to an increase in the amount of DMA excreted and hence an elevation in the urinary arsenic speciation total. Urine samples collected from volunteers between 4-20 hours after the ingestion of moderate-sized portions of mackerel, herring, crab or tuna, showed mean increases in the arsenic speciation totals of between 1.8 and 6.9 times compared with the levels in samples collected before the seafood was consumed. These findings have important implications in devising a biological monitoring strategy for workers exposed to inorganic arsenic. (PMID: 1483034, UI: 93130077).

I. Arsenic in Asian medications (8)

  1. Some homeopathic medicines have been found to contain arsenic.

  2. Asian folk remedies have been reported to contain levels of arsenic that have resulted in arsenic poisoning with elevated arsenic levels of up 3,334 microgramme/24 hr in among Southeast Asian refugees.

  3. Folk remedies from China (various Chinese herbal balls) and India (chandraprabha, maya yograj guggul and others), have also been found to contain arsenic.

  4. Wine produced from grapes grown in vineyards treated with an arsenical pesticide has been postulated to cause arsenic poisoning in at least one case.

  5. In Iran, an arsenic sulphide (AS2S3) compound with calcium oxide and starch is mixed with water to form calcium hydroxide, and then used as depilatory.

J. Arsenic in Cigarettes

  1. Do you know that cigarettes expose smokers to arsenic?  

  2. Nicotine, an addictive substance in cigarettes, is three times more toxic than arsenic.  

K. Arsenic-containing Pesticides in Malaysia (9)

  1. Celsol SD (11.9 % w/w Arsenic acid)
  2. Celcure A (P) (24.5 % w/w Arsenic pentoxide dihydrate)
  3. Celcure AN (29.0 % w/w Arsenic pentoxide dihydrate)
  4. Celcure B ( 2.64 % w/w Arsenic pentoxide dihydrate)
  5. Copas LC (22.4 % w/w Arsenic pentoxide dihydrate)
  6. Copas LCX (24.5 % w/w Arsenic pentoxide dihydrate)
  7. Copas LCX 2 (19.0 % w/w Arsenic pentoxide dihydrate)
  8. Copaseal ( 2.64% w/w Arsenic pentoxide dihydrate)
  9. Impretect 95 CP (19.0 % w/w Arsenic pentoxide dihydrate)
  10. Tanalith C (20.0 % w/w Arsenic pentoxide dihydrate)
  11. Timpro 95 (25.0 % w/w Arsenic pentoxide dihydrate)
  12. Timpro 95 CP (19.0 % w/w Arsenic pentoxide dihydrate)
  13. Timpro 95 (25.0 % w/w Arsenic pentoxide dihydrate)
  14. TP - CCA 95 (25.0 % w/w Arsenic pentoxide dihydrate)

L. Other Arsenic-related compounds (10)

- Arsenic Acid (CAS# 7778-39-4)

  1. Description: White translucent crystal; commercial grade is a very pale yellow, syrupy liquid.

  2. Carcinogenicity: IARC - Group 1, Carcinogenic to humans

- Arsenic Pentoxide (CAS# 1303-28-2)

  1. Description: White powder, Odourless

  2. Health Hazards: Irritating to eyes/skin/respiratory tract. Poison.

  3. Other target organs: Nervous system, liver, blood

  4. Carcinogenicity: IARC - Group 1, Carcinogenic to humans

M. Conclusions (2)

  1. Exposure of general population to arsenic compounds occurs predominantly via food and drinking-water. Over-exposure in the working environment and during agrricultural application occurs mainly through inhalation

  2. The acute toxicity of the inorganic arsenic compounds for man is very high. The smallest, fatal, single dose for a human is in the range of 70-180 mg. With long-term exposure, significant toxic effects can be expected to occur above a daily oral intake of 100-200 microgramme.

  3. The main chronic effects of inorganic arsenic compounds are damage to the nervous system and hyperkeratosis of the skin, leading to skin cancer

  4. Inorganic arsenic is a proven human carcinogen after long-term oral intake, as well as after inhalation.

  5. Arsenic is moderately toxic for fish and aquatic invertebrates but highly toxic for some algal species. There is field evidence of arsenic affecting aquatic ecosystems.

M. Sources*

  1. Guidance Document for Arsenic in Shellfish, Center for Food Safety and Applied Nutrition, USFDA, January 1993

  2. Health and Safety Guide No. 70, International Programme on Chemical Safety, 1991

  3. International Chemical Safety Cards, International Programme on Chemical Safety & the Commission of the European Communities, 1993

  4. Handbook of Medical Toxicology (ed. P Viccellio), Chap. 26 Cadmium, Mercury, and Arsenic, p. 290. 1993

  5. Arsenic - General information, City of Los Angeles Water Services - Water Quality, 1996

  6. Arsenic Affects the Whole Body. Report on Medical Survey in West Bengal, India by Nobuyuki Hotta, 1996

  7. Arbouine MW, Wilson HK, The effect of seafood consumption on the assessment of occupational exposure to arsenic by urinary arsenic speciation measurements, J Trace Elem Electrolytes Health Dis., 1992, Sept. 6 (3):153-60

  8. Inorganic Arsenic, Micromedex, Rocky Mountain Poison Center, Colorado. 1999

  9. Registered Pesticides 1995-1997, Pesticides Board Malaysia, 1998, p. 63-65

  10. Genium's Handbook of Safety, Health and Environmental Data for common hazardous substances, Vol. 1, 1999, p. 275-277

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Last updated: 14 September 1999