MDEP study 'misinterpreted' information on perchlorate, says doctor
By Carrie Saldo
North Adams Transcript
June 8, 2004
WILLIAMSTOWN -- The Massachusetts Department of Environmental Protection "misinterpreted" some information in a study it is using to establish a toxicity level for perchlorate, according to study co-author Dr. Richard Pleus.
The perchlorate levels found in Mount Greylock Regional School District's water supply are significantly lower than what the Greer study found to have no effect in the body.
The Greer study set out to find a dose of perchlorate that would cause no effect in the body. It was used by the Massachusetts Department of Environmental Protection when it established a draft toxicity value for perchlorate at one part per billion.
Perchlorate was discovered in Mount Greylock Regional School District's water after it tested its water in April. The most recently released water test results for Mount Greylock showed 9.6 parts per billion of perchlorate in the south well at the school and 2.5 parts per billion in the north well.
Mount Greylock has been using bottled water for cooking and consumption since the chemical, which some say can alter the successful function of the thyroid, was discovered.
The DEP didn't use one of main points of the Greer study, which sought to determine an amount of perchlorate within the body that would not effect iodine uptake, said Pleus, who is director of toxicology for Intertox, and a University of Nebraska Medical Center professor.
"That has been missed completely in the MDEP risk assessment," he said. " ... I think [the study] was misinterpreted on some of the key points."
The Greer study saw no change in the human body when humans ingested 17,500 parts per billion of perchlorate.
Perchlorate has been used medicinally for about 50 years. Perchlorate was used to treat hyperthyroidism -- overactive thyroid -- because it inhibits the production of iodine, which is needed in order for the body to produce the thyroid hormone. However, since the late '50s and '60s, other medications have proven more effective in smaller doses for treating hyperthyroidism.
The federal government does not set a standard for perchlorate. However, in February the DEP began requiring that all public water suppliers test for the presence of this chemical.
The perchlorate levels found as a result of the testing will be used to by the DEP to establish a maximum contaminant level.
Water with more than one part per billion of perchlorate should not be consumed by "sensitive populations" -- pregnant women, infants, pre-pubescent children, and people with hyperthyroidism, according to the DEP.
Higher levels of perchlorate exposure are safe for those not categorized as "sensitive," although the DEP has said levels of 18 parts per billion are considered a health risk for the general population.
According to the Greer study, the highest dose of perchlorate used in the study was 0.5 milligrams per kilogram, or 17,500 parts per billion in water. The DEP has preliminarily set its threshold at one part per billion.
Thirty-seven men and women, who had full toxicology screens completed prior to being given the perchlorate, were given one of four different doses of perchlorate at random with a maximum of 0.5 milligrams per kilogram for the study.
Pleus said he and others were noting what change if any the different doses had on the people in the study.
They found that the 0.5 dose inhibited up to 70 percent of the cells that bring iodine to the thyroid gland. But, even with 70 percent of the cells not functioning, Pleus said the level of iodine within the test subjects' bodies went unchanged.
"That didn't surprise us because the body compensates," Pleus said.
The DEP used parts of the Greer study and a study that tested the effects of perchlorate on laboratory rats to help determine its draft toxicity level.
Pleus said that he and many scientists are concerned about the quality of the data in the lab rat study.
The Greer study was conducted in 2000 and published in 2002.
Ed Colletta, of the DEP, could not be reached for comment Monday.