Analytical Chemistry Trinidad & 

Tobago Lab Resources

ARSENIC METAL POISONING


HOME Email

Related links :
Lead poisoning
Mercury poisoning

Arsenic Poisoning

GENERAL

Arsenic (As) is a metallic steel-grey element with Atomic mass 74.92, Atomic number 33, Melting point 1090 K (1502 deg F; 816 deg C), Boiling point 887 K (1135 deg F; 613 deg C;), Density 5.72g/cc.

Arsenic is found in nature at low levels in rock, soil and air (geological origen) and in ground water used for drinking and irrigation. It is found in combination with oxygen, chlorine and sulphur to form inorganic arsenic compounds such as Asenites and Asenates.
Asenic in plants and animals combine with carbon and hydrogen to form organic arsenic compounds. Examples are Asenobetaine and the tetramethylarsonium salts. Organic arsenic is less harmful than inorganic arsenic. Metallic arsenic (As) however, has very low toxicity because it is almost insoluble in water and body fluids. Most arsenic salts can dissolve in water. The inorganic arsenic salts are the most toxic by inhalation,ingestion and skin contact.

use

Inorganic arsenic compounds are mainly used as a preservative for wood treatment and curing. Arsenic is also used with chromium and copper (CCA) to make pressure-treated lumber. They are also used to make insecticides and herbicides due to their toxicity to insects, bacteria and fungi.

route to exposure

The industrial processes of energy production by fossil fuel and smelting of non-ferrous metals lead to arsenic contamination of air, water, and soil. The suspended arsenic dust and particles will eventually settle to the ground and enter the food chain.
Emissions from the manufacture of arsenic pesticides and wood preservatives will also enter the food chain.
Asenic contaminated water. Arsenic containing mineral and particulates washed out and leached into groundwater used for drinking.
Arsenic contaminated food. Food contaminated by spraying of arsenic pesticides or the storage of food into wooden containers treated with arsenic.


Occurence

It doesn't evaporate.
Most arsenic compounds can dissolve in water.
It gets into air when contaminated materials are burned.
It settles from the air to the ground.
It doesn't break down, but can change from one form to another.
Fish and shellfish build up organic arsenic in their tissues, but most of the arsenic in fish isn't toxic.

Exposure

Breathing sawdust or burning smoke from wood containing arsenic.
Breathing workplace air.
Ingesting contaminated water, soil, or air at waste sites.
Ingesting contaminated water, soil, or air near areas naturally high in arsenic.

Health Effects

Inorganic arsenic compound are poisonous by inhalation of arsenic dust or fumes and by ingestion or skin contact of arsenic contaminated food.
Toxic effects relate to Short term exposure (acute) and Long term exposure (chronic). Regardless of exposure time or type, Regardless of exposure time or type, all arsenic toxicities eventually produce similar effects and symptoms characteristic of severe gastroenteritis and neuropathy. These symptoms may be delayed and occur long after exposure.
When arsenic is ingested, it is methylated by the liver and excreted in the urine, and by the skin through perspiration. After a few days the arsenic is cleared from the blood and exposure tests become negative, but the effects of poisoning remain.
Observable signs of arsenic poisoning can be seen as white transverse bands in the hair and fingernails (Mees' lines) which is the binding sites of arsenic with sulfhydryl containing proteins.
Arsine is a gas consisting of arsenic and hydrogen. This gas is very toxic to humans and cause headaches, vomiting, and abdominal pain with only a few hours of exposure. The EPA has classified inorganic arsenic as a human carcinogen, but has not classified Arsine for carcinogenicity. The organs of the body that are most likely to be affected are the Lungs, Skin, Kidneys and Liver.
Skin
Bronzing of skin, edema,dermatitis and lesions. Blackfoot disease, a vascular problem with gangrrene effects.
Inhalation
Damage to nasal septum, dermatitis, gastrointestinal problems, respiratory irritation, hyper-pigmentation of skin, peripheral neuropathy.
These symptoms may be similar to the ingestion effects and vice versa.
Ingestion
Burning in oesophagus, vomiting, bloody diarrhea, abdominal pain, weakness, headache, cramps, shock, collapse, unconsciousness, convulsions and coma.
Hair loss, weight loss, excessive salivation and perspiration. Garlic odor to breath and sweath.
Central nervous system damage, peripheral neuropathy, hyper-keratosis, anemia, cardiovascular damage, liver and kidney damage.
Death from circulatory failure.
Children
No levels of arsenic are considered safe when it comes to children. They are more vulnerable to arsenic poisoning and suffer severe loss of speech, seizures, rash, brain damage, and even cancer of the Lung, Skin or Bladder.

summary

Inorganic arsenic is a human poison.
Organic arsenic is less harmful.
High levels of inorganic arsenic in food or water can be fatal.
A high level is 60 parts of arsenic per million parts of food or water (60 ppm).
Arsenic damages many tissues including nerves, stomach and intestines, and skin.
Breathing high levels can give you a sore throat and irritated lungs.

Lower levels of exposure to inorganic arsenic may cause:

Nausea, vomiting, and diarrhea
Decreased production of red and white blood cells
Abnormal heart rhythm
Blood vessel damage
A "pins and needles" sensation in hands and feet

Long term exposure to inorganic arsenic may lead to a darkening of the skin and the appearance of small "corns" or "warts" on the palms, soles, and torso.
Direct skin contact may cause redness and swelling.

Breathing inorganic arsenic increases the risk of lung cancer.
Ingesting inorganic arsenic increases the risk of skin cancer and tumors of the bladder, kidney, liver, and lung.

Exposure Tests

Tests can measure your exposure to high levels of arsenic.
These tests are not routinely performed in a doctor's office.
Arsenic can be measured in your urine. This is the most reliable test for arsenic exposure. Since arsenic stays in the body only short time, you must have the test soon after exposure.
Tests on hair or fingernails can measure your exposure to highlevels of arsenic over the past 6-12 months. These tests are not very useful for low level exposures.
These tests do not predict whether you will have any harmful health effects.

The Environmental Protection Agency (EPA) sets limits on the amount of arsenic that industrial sources can release.
It restricted or canceled many uses of arsenic in pesticides and may restrict more.
EPA set a limit of 0.05 parts per million (ppm) for arsenic in drinking water.
EPA may lower this further.

The Occupational Safety and Health Administration (OSHA) established a maximum permissible exposure limit for workplace airborne arsenic of 10 micrograms per cubic meter (g/m).

The Department of Health and Human Services (DHHS)has determined that arsenic is a known carcinogen.


Reference:

1. "Mercury Free", by Dr. James Hardy.
2. WHO. Arsenic and Arsenic Compounds . Environmental Health Criteria, vol. 224 . Geneva: World Health Organization, 2001


delloyd.50megs.com

Signature: Dhanlal De Lloyd, Chem. Dept, The University of The West Indies, St. Augustine campus
The Republic of Trinidad and Tobago.
Copyright: delloyd2000© All rights reserved.