Inorganic arsenic has been recognized as a human poison since ancient times. Arsenic is a highly toxic, naturally occurring grayish-white metal-like material. Inorganic arsenic is created when elemental arsenic combines with oxygen, chlorine and sulfur. Inorganic Arsenic has been used as a poison in pesticides and herbicides, and is used in making CCA pressure Treated wood. An extremely toxic poison, it is colorless and odorless.
Soil: It has been reported that EPA has set a limits of 10 ppm (10 mg per kg) of arsenic in soil. Arsenic levels over this limit empower EPA to order an owner-funded cleanup of a commercial site. (1). However; I have been unable to locate a hard citation to this figure. If anyone out there can find a reference from EPA on this, please let me know.
Air: The Occupational Safety and Health Administration, OSHA, established a maximum permissible exposure limit for workplace airborne inorganic arsenic of 10 micrograms per cubic meter averaged over an eight-hour day.
Presence: Inorganic arsenic is found in many kinds of rock, especially in ores that contain copper or lead. When these ores are smelted to extract the copper or lead, most of the arsenic is collected for pesticide. Like radiation, everyone is exposed to low levels of arsenic (especially inorganic arsenic) because very low levels of it are always present in soil, water, food and air. The average person ingests about 8 micrograms (about 8/1000 of a gram) in food every day. Arsenic is also present in cigarette smoke where it originates from insecticides on tobacco.
Uptake Mechanisms: Arsenic can be taken in by ingestion, aspiration by breathing dust, and, to a much lesser degree, by absorption through the skin. Accidental poisoning has been reported to occur from wearing inadequate clothing when applying arsenic-based products.
A lethal dose of Arsenic can also be achieved by a cumulative process. Multiple sub-lethal doses received over a period of several weeks can accumulate in the body to achieve a lethal dose. And at very small doses, arsenic is carcinogenic.
Exposure to high levels of inorganic arsenic - greater than 100 ppm parts of arsenic in food or water - can also be fatal. Arsenic and arsenic compounds are known cancer-causing agents and have been implicated in lung and skin cancer and associated with birth defects. While organic arsenic (arsenic combined with carbon compounds) is less toxic it causes similar effects.
More detailed toxicity information for the medical community can be found at: Risk Assessment Information
Arsine Gas: Arsine gas (AsH3), is produced when elemental or inorganic arsenic reacts with zinc compounds or certain fungi. Even at concentrations as low as 3-10 ppm, Arsine gas can cause toxic effects in a few hours RAIS data . Where Arsine gas is encountered at very low levels the onset of illness is slow and insidious. After a period of months, cumulative hemolytic effects present as resting dyspnea (breathlessness), severe exercise intolerance and a tachycardia (rapid pulse rate). These signs may be coupled with vague neurological symptoms with a strange feeling in the legs. Hypoxia resulting from exposure to low levels of Arsine gas can lead to blackouts of varying duration.
At this stage removing the source of contact with Arsine gas may not help, because of the 'latency period' of one to six months in the development of neurological symptoms. Recovery from the hemolytic effects leads to a compensatory condition 'polycythemia' an excess of red blood cells, in patients with normal RBC metabolism.
Lengthy low-level exposure to Arsine gas leads to a third stage of the illness which has similarities to the onset of acute arsine gas poisoning, including brown urine, dizziness, headache and delirium. This is followed by progressive paralysis of the legs and arms leading to 'foot drop', 'wrist drop', 'ataxia' and generalized symptoms including problems with 'proprioception' or position sense.
Recovery from sub-lethal Arsine exposure is slow: six months of variable paralysis followed by a recovery time of two to four years. Depending on exposure, there is a possibility of permanent nerve damage affecting the extremities, particularly the hands and fingers.
The effects of Arsine gas on infants and the fetus are not well documented, but there is some anecdotal evidence. In the late 1950s the New Zealand military, treated bedding and sheep skins used for crib pads with an arsenic compound as a fungicide (Arsenic is still used as the fungicide in CCA wood). However, a fungus called 'Scopulariopsis breviculis' can metabolize arsenic and emits arsine gas as a by product. Arsine gas may have been responsible for a high rate of infant mortality from sudden infant death syndrome (SIDS) in New Zealand. Cot death or SIDS was abnormally high in military families where arsenic was used as a fungicide in 'Official Issue' bedding.
A prestigious institution of clock makers has circulated a warning to its members that in the renovation of old clocks there is a danger of Arsine gas poisoning due to the pigment 'Scheeles Green' used in fret screens.
The same fungus 'Scopulariopsis breviculis' mentioned above was responsible for the 'Wallpaper and paste' poisonings of the 19th century in Europe. Arsenic used as a fungicide in wallpaper was metabolized by the fungus and Arsine gas released.
The question for us is, will this fungus attack CCA Pressure-Treated Wood?.
Information on Arsine Gas courtesy of Brian Shadd, Diagnostic engineers, UK
Signs of long-term exposure include (1) development of white crescent-moon marks on the fingernails (2) a darkening of the skin, skin lesions, a skin rash and the appearance of small warts on the palms, soles and torso, mottled spotting of the skin pigmentation, looking like 'raindrops on a dusty road'.
Chelating agents bind tightly to metals like arsenic and mercury, and can help in eliminating these from the system. See information on Chelation treatment from a clinic in Atlanta, and on specific chelation agents from S.E.R.B labs, a pharmaceutical company in France.
For more information about the toxicity of arsenic, contact:
Mike Kamrin
Institute for Environmental Toxicology
C231 Holden Hall, MSU
Phone: 517-353-6469
Agency for Toxic Substances and Diseases Registry
Division of Toxicology
1600 Clifton Road NE
Mailstop E-29
Atlanta, GA 30333
Phone: 404-639-6000
1. This Old House Magazine, Issue 17, March/April 1998, Page 118-125
Page Last updated: August 2000