By KEVIN PROFT/ecoRI News staff
PROVIDENCE — Arsenic was first ban as a poison in Rome by Consul Lucius Cornelius Sulla in 82 B.C., thanks to its use in countless assassinations. In 1365 A.D., the Italian city of Siena prohibited sales of arsenic to slaves, servants and children, in order to prevent them from causing harm, intentionally or unintentionally, to themselves or others.
The Sale of Arsenic Regulation Act of 1851 required English merchants to keep written records for each customer they sold arsenic. If they didn’t know the customer, the customer needed to supply a witness that the seller did know.
In each of these instances, arsenic was regulated in order to protect people from murder or unintentional personal harm. Despite its reputation as a potent poison, arsenic also has been used throughout history in less-sadistic ways. The Chinese have used arsenic as a medicine for 3,000 years; Hippocrates used it in a tonic in ancient Greece. Arsenic has been prescribed to treat diseases ranging from malaria to diabetes and is still sometimes used to treat leukemia today.
Arsenic also is used today as a wood preservative. Once used to protect the planks of decks and playgrounds, it’s now reserved for wood in locations where human contact is rare.
While all of these uses for arsenic have, to some extent, resulted in unintended negative consequences, it is arsenic’s use as a pesticide and herbicide that has left the most damaging legacy. Arsenic, until recently, was sprayed on countless lawns and farms across Rhode Island to combat unwanted weeds and insects.
Its use in almost all situations has been phased out by the Environmental Protection Agency (EPA) — notable exceptions being cotton farms, sod farms, golf courses and highway right-of-ways — but it still lingers in Rhode Island’s soil, which has led to a whole new set of arsenic regulations that focus on the remediation of contaminated sites rather than the prevention of assassinations.
There are 850 sites across the state with soil contaminated by arsenic, according to Kelly Owens, associate supervising engineer for the state Department of Environmental Management (DEM). Arsenic is a known carcinogen and can enter the body through inhalation, ingestion or absorption, said Owens, who recently presented at a Superfund Research Program Seminar at Brown University.
Since 1996 Rhode Island has regulated arsenic in soils. The regulations initially required soil remediation on sites with arsenic levels higher than 1.7 milligrams/kilogram, but in 2004 the DEM determined that this standard was too low. Since arsenic also occurs naturally in soils, developers were having difficulty complying with the 1.7 mg/kg standard even at sites where arsenic herbicides were never applied. A new study was conducted and a ratio of 7 mg/kg was adopted.
The 2004 regulations also offered a range of remediation strategies to developers when arsenic levels registered above 7 mg/kg. Soil could be excavated and removed, capped with uncontaminated soil, capped with an impervious surface such as asphalt or blended with uncontaminated soil to reduce the ratio of arsenic in the soil. Site-specific strategies could also be developed and submitted for review. If soil contamination was above 15 mg/kg, cap depths were substantially increased.
In 2011, the standards were updated again, based on the findings of the Legislative Commission on Arsenic. While the commission kept the existing 2004 benchmarks for contaminated sites at 7 mg/kg and 15 mg/kg, it weakened the regulations in many other areas.
Under the 2011 standards, developers have to compile fewer samples when testing a site for arsenic than they did under the 2004 regulations and more of those samples can be above 7 mg/kg as long as the average of the entire site is less than 7 mg/kg. Soil cap depth requirements for sites above 7 mg/kg were reduced from 6 inches to 4 inches, while asphalt cap requirements decreased from 3 inches to 2 inches. For sites above 15 mg/kg, soil cap requirements were reduced from 2 feet to 6 inches, while asphalt cap requirements were reduced from 4 inches to 2 inches.
The 2011 standards also waived the requirement for annual monitoring and reporting of arsenic levels on contaminated properties for some landowners.
The Legislative Commission on Arsenic whose findings led to the less-stringent 2011 standards was created because of complaints from housing groups, such as the Newport Housing Authority, about the fiscal impacts arsenic remediation was having on development. In order to spur construction, the state’s arsenic regulations were weakened. The commission included legislators, housing groups, the DEM, the Department of Health and residents.
Tale of Three Remediations
The Kempenaar Valley property in Middletown is one of the sites currently being monitored for arsenic contamination. Kempenaar Valley is a 33-acre former farm, and the site’s 9.6 mg/kg arsenic level is likely the result of herbicides that were used on the farm.
Middletown wants to use the site as an open space with walking trails and a farmers market but first needs to remediate the property’s soil. The town secured a $200,000 federal grant to clean up the site, but needed to match the grant at 40 percent. Town officials recently determined they wouldn’t be able to come up with the matching funds and returned the grant money. The site is still contaminated and is commonly used by local residents as a place to run or walk dogs.
Tonomy Hill in Newport was once a Navy housing facility. The old houses are being torn down and replaced with new affordable housing. The soil is contaminated with arsenic, likely because the Navy used arsenic herbicides and pesticides on the site. The Newport Housing Authority has completed four of its five building phases under the 2004 standards, but complained that the standards were too great a burden on the project before commencing with the fifth phase. This was the main force behind the 2011 change in arsenic standards.
The lawn of the Beechwood Mansion in Newport, a residential property owned by the wealthy Astor family, is contaminated with arsenic. The owner has decided to remove the top 2 feet of soil and replace it with uncontaminated soil. The old soil likely will be used by the Rhode Island Resource Recovery Corporation as cover for the Central Landfill in Johnston. Soils with less than 20 mg/kg of arsenic can be used as landfill cover.