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Arsenic and Old Waste

by aseligmann — last modified Jul 02, 2010 12:00 AM
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Arsenic is a notorious toxin and it has been used in pesticides -- past and present. Arsenic is toxic to a variety of living things, so it has been used in different kinds of pesticides - insecticides, fungicides, & herbicides. Because it does not degrade, arsenic can continue to be a problem wherever it has been used. People are exposed to these arsenic residues mainly through skin contact with contaminated soil or treated wood surfaces. Children can 'eat' arsenic when they put their hands in their mouths after touching arsenic-laced wood or soil. The US Environmental Protection Agency classifies inorganic arsenic* as a cancer-causing agent in humans. It is linked to many kinds of cancers. Animal studies show that inorganic arsenic can cause birth defects.

Arsenic is a notorious toxin and it has been used in pesticides -- past and present. Arsenic is toxic to a variety of living things, so it has been used in different kinds of pesticides - insecticides, fungicides, & herbicides.

Because it does not degrade, arsenic can continue to be a problem wherever it has been used. People are exposed to these arsenic residues mainly through skin contact with contaminated soil or treated wood surfaces. Children can 'eat' arsenic when they put their hands in their mouths after touching arsenic-laced wood or soil.

The US Environmental Protection Agency classifies inorganic arsenic* as a cancer-causing agent in humans. It is linked to many kinds of cancers. Animal studies show that inorganic arsenic can cause birth defects.

Arsenic the Insecticide

The historical use of lead arsenate as an insecticide in apple orchards has come back to haunt us years later. Lead arsenate was used to control codling moth from the 1800s to the 1940s (when DDT became available), leaving behind both arsenic and lead in the topsoil. In recent years, as apple orchards were converted to housing developments, new owners discovered that their new yards and gardens were contaminated.

Similar stories unfolded in New York, Connecticut, New Jersey, Washington State, and other states. There were no regulations in place to protect unsuspecting home buyers or to remedy the situation. (The only 'remedy' for contaminated soil is to dig it up and put it somewhere else). Now some states try to warn the public about this problem but regulations may be left up to local jurisdictions. Oregon has chosen to be proactive by using hazardous substance clean-up rules so they can investigate and get sites cleaned up.

Arsenic the Fungicide & Insecticide (Wood Preservative)

CCA (chromated copper arsenate) is the best known of the arsenical wood preservatives. The treated wood has a characteristic greenish tint. This wood has been widely used in decks and play structures.

New studies have shown that soil beneath these treated structures have higher levels of arsenic than the surrounding area. There is also evidence that arsenic from play structures can rub off on hands - a particular concern for children.

CCA was first used in the 1940s. In 2003, CCA-treated wood was phased out for most uses in residential settings.

Arsenic the Herbicide

Arsenic is still being used in lawn and turf herbicides. Products with names like All-In-One Weed Killer, Crabgrass Killer, Liquid Edger may contain one of four different arsenic compounds. EPA is currently (2006) reassessing the risks from these herbicides in order to decide whether they should be re-registered under newer standards. EPA says that use around homes may present "risks of concern" for toddlers, noting that they may also be exposed to arsenic through food and water.

Pesticides are registered on a risk-benefit basis. The benefit of using these arsenical herbicides in lawns is, presumably, a perfect lawn with little work. The other part of the equation is determining whether these herbicides cause "unreasonable risk" to health and the environment. Ask yourself -- What would be a reasonable risk for your child?

Arsenic Stays with Us

In the end, all of this arsenic will end up somewhere - usually in topsoil and water.

In 2005, Florida researchers published a study showing high levels of arsenic in runoff (water) and in soil under treated decks. They estimated that 28,000 metric tons of arsenic had been imported into Florida by 2000, and that 4,600 tons had already leached into the environment. Over the next 40 years they predict that decks and other structures will leach out an additional 11,000 tons.


 

* NOTE: Arsenic can change its form, transforming from organic arsenic to inorganic arsenic (or vice versa) depending on various conditions. It is the inorganic form that is most likely to harm health. Inorganic arsenic is used in CCA and other arsenical wood preservatives. Lead arsenate, the old insecticide, contained inorganic arsenic. The arsenic in present-day herbicides is in the organic form. However some of it may transform into inorganic arsenic in the environment.

 

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