Arsenic in Local Soils: Risks in Perspective — Peter Garnham
Constant Harvest • Volume 4 Number 1 • April 2005 Updated: 04/10/06
Concern has recently been expressed by some well-meaning folks who were shocked to learn that arsenic can be found in farm soils. To those unfamiliar with basic soil chemistry, this may seem alarming. Arsenic is a naturally-occurring semi-metallic element1, found in varying amounts (from 0.1 to 97 parts per million2) in soils throughout the United States. It is known to be present in farm, home, and school soils in all parts of East Hampton, other areas of Suffolk County, and eastern Nassau County. It is a necessary plant nutrient, and in trace amounts is believed to be a necessary nutrient for mammals, including humans.3
Several forms of arsenic were once widely used in agricultural and horticultural pesticides and fertilizers4. The heaviest users in this region were up-state commercial orchards, but pest-control companies, potato farmers, and homeowners also used these chemicals. The use of a wood preservative containing arsenic, CCA, has been limited. It is possible that tiny residues of these chemicals remain, in addition to those put there by nature. However, no known cases exist in the U.S. of arsenic poisoning from soil contact, ingestion, or inhalation.
The U. S. Environmental Protection Agency has established a maximum limit for arsenic in drinking water5, but not in soils, because there is no scientific evidence on which to base a “safe” level of arsenic in soils. Several states, including New York, have established so-called acceptable levels, not based upon any evidence of health risks, but simply pegged to the naturally-occurring levels within that state.
Clearly, arsenic is all around us. It is quite possible that home gardens (especially those of houses built on former farmland), school playing fields, and all farm fields will show traces ranging from about 20 ppm (parts per million) to about 50 ppm.
Most farm fields in East Hampton and Southampton, from which our local food supply comes, are still farmed “conventionally” - that is, using chemical fertilizers and pesticides. Almost all those chemicals are highly toxic, even if they do not contain arsenic. EECO Farm in East Hampton, Quail Hill Farm in Amagansett, and the Green Thumb in Watermill, are farmed organically, without chemical inputs of any kind. An increasing number of privately-owned farms are starting to follow organic practices.
Organic farming concentrates on soil improvement. Constant applications of compost, and the seasonal growth of dense cover crops, add vegetative matter to the soil, thus cleaning the soil of earlier chemical contaminants. The result is lush, green, and healthy crops that would not thrive in contaminated soils. We recommend that people with health concerns should wear gloves and avoid breathing dust.
While we should not shrug off the possible hazards from arsenic and other chemicals, we must keep these risks in perspective. Those concerned about this issue should investigate home and school areas, where children spend much more time than in visiting farms, and where no attempt is being made to improve soil health or limit exposure. Farm fields that are being farmed organically are “the good guys,” the healthiest soils on Long Island, and they should be held up as a standard to which others should aspire.