Frying pan to fire

US environment agency cool with chemicals

By Nidhi Jamwal
Published: Friday 31 March 2006

Limited options: Carcinogenici (Credit: USDA)the United States Environmental Protection Agency (usepa) is in the process of replacing methyl bromide, an ozone-depleting fumigant, with methyl iodide, a highly toxic and carcinogenic chemical. The issue of replacement was open to public comment till February 21, 2006 and the final decision is expected in late March.

Methyl bromide is used as a fumigant to sterilise soil before planting strawberry, peppers, tomatoes, grapes and several other crops. However, the chemical is included in the list of ozone-depleting chemicals that were to be phased out under the Montreal Protocol. While most nations have complied with this, the us has been pressing the un to let it use the chemical under a "critical use" clause, saying that the country does not have a replacement.

Now, usepa is planning to approve the use of methyl iodide as a replacement. The gas, though not ozone depleting, can be dangerous if inhaled.

As per the usepa's January 5, 2005 risk assessment, breathing methyl iodide in large doses causes miscarriages, thyroid tumours and respiratory tract damage. Studies further show it can alter thyroid hormones, essential to regulating the growth of a healthy foetus.

Based on recent field tests for the chemical, conducted in California and Florida, epa toxicologists concluded that unprotected farm-workers could breathe harmful doses. The chemical in low concentrations could even drift off fields, thereby affecting the neighbouring people.

The toxicologists also determined that the workers would be safe if they wore respirators and that the people near the fields would breathe such small amounts that they would face no known health risk.

The registration decision by epa will have no bearing on our process. It has to pass muster in California (one of the states where field tests were conducted), said Glenn Brank, a spokesperson for the state pesticide agency. Methyl iodide is highly toxic, says Brank, and there are "a number of areas of concern reproductive and developmental toxicity as well as carcinogenicity.

On the other hand, although fumigants are problematic, they also are essential, given the lack of alternative soil treatments at present, Brank said.
Environmental groups have opposed the epa's step. This is an archaic, unsustainable approach, says Susan Kegley, senior scientist, Pesticide Action Network North America. epa should be helping farmers move into the future by expanding the use of new integrated pest management techniques, not replacing one deadly chemical for the other, Kegley said.

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