Chemists develop first accurate test for arsenic in soil

Washington, April 5 (ANI): Analytical chemists have developed the first accurate test for arsenic compounds in soil, providing improved environmental and health impact assessment, and for detecting high arsenic levels in some Asian rice supplies.

The test was conducted by analytical chemist Julian Tyson and colleagues at the University of Massachusetts Amherst in the US.

In North America, arsenic is found most commonly under decks and near structures such as playground gyms made of pressure-treated wood, which is impregnated with heavy metals.

The squeezed-in chromium, copper and arsenic make wood weather-resistant and durable but they also slowly leach out into the environment, mainly soil.

The potential health impact, called by some an "environmental time bomb," has been difficult to assess in an objective, quantitative way until now, according to Tyson and his graduate student co-author Khalid Al-Assaf, because the key arsenic compounds stick so tightly to iron oxides that they couldn't be isolated and measured separately.

"It's been very hard to know if this source of contamination was staying put, evaporating into the air or getting into the groundwater," Tyson explained.

Several laboratories have long sought a soil test for arsenic, but his research team is the first to develop a procedure for isolating all the compounds of interest, including the mono- and dimethylated species in soil and accurately measuring them.

With the new procedure, chemists can now help to answer questions about whether arsenic compounds are getting into drinking water supplies, being taken up by plants, and whether soil bacteria are involved in the production of methylated compounds.

It's already known that arsenic is easily ingested by children who touch pressure-treated wood play equipment and then put their hands in their mouths, and it's brought into homes on pets that get into dirt under pressure-treated wood decks.

According to Tyson, earlier attempts to trace arsenic movement through the environment by sampling dog toenails were not conclusive.

The chemist added that because some bacteria in soil are able to convert arsenic to volatile products, and iron oxides can bind it tightly, the residue in the soil may not travel very far, so "we probably shouldn't be unduly alarmed."

Tyson and colleagues' method for isolating the arsenic compounds from soils may be adaptable to determine arsenic concentrations in batches of rice to improve food safety. (ANI)