NAS report finds perchlorate not as toxic as first believed
January 12, 2005
WASHINGTON " In a long-awaited report released Jan. 11, the National Academy of Sciences concluded that people can safely tolerate more perchlorate " a chemical that has leached into milk, food and water supplies in trace amounts " than the Environmental Protection Agency had thought was safe.
The issue has become a lightning rod for environmentalists, health officials, defense contractors and Pentagon officials who are all battling over the appropriate drinking water standard and what could become a costly cleanup of water supplies that have become polluted with the rocket fuel byproduct. While experts agree that large doses of perchlorate can hamper the thyroid gland?s normal functions, the debate over low doses has pitted federal agencies against one another.
Specifically, NAS found that the most sensitive populations could safely ingest 0.0007 milligrams per kilogram of body weight of perchlorate on a daily basis. This is more than 20 times the reference dose proposed by EPA in its draft risk assessment, which has been driving EPA towards a one part per billion drinking water standard. NAS officials refrained from speculating on a new drinking water level as health officials must weigh a variety of factors " not only science " to agree on an appropriate number, the panel said.
EPA and NAS arrived at much different safety levels by disagreeing over the use of animal data. EPA predicted that exposure would lead to thyroid tumors, as they had in a few studies involving rats. But NAS said that perchlorate exposure was unlikely to lead to thyroid tumors in humans because people are much less susceptible than rats to disruption of thyroid function or formation of thyroid tumors.
The scientific debate is of great concern to produce growers as the Food & Drug Administration has been finding trace amounts of perchlorate in lettuce and milk, and the agency has yet to announce its results for tomatoes, carrots, cantaloupes and spinach.
?The National Academy of Sciences report is another valuable tool to help us better understand the impact, if any, of perchlorate," said Hank Giclas, vice president of science and technology for Western Growers Association. "The safety of our food supply is the highest priority of Western Growers, the farmers and all those who are involved in the production, processing and delivery of fresh fruits, nuts and vegetables.
?We employ many practices, such as verification of quality water sources, good agricultural and manufacturing practices, and compliance with all local state and federal regulations, to ensure our food supply is safe," continued Mr. Giclas. "We will fully review the findings of the National Academy of Science committee to determine what further actions growers, packers and shippers should take to further enhance the safety of our products."
?The most important thing to note is that FDA has indicated consumers should eat plenty of fruits and vegetables and should not change eating habits because of perchlorate," said Kathy Means of the Produce Marketing Association. "I don?t expect this report to change FDA?s stance on this, but we will be interested in hearing that agency?s reaction. "Certainly numbers for water do not equate to numbers for food, and we?ll need to evaluate the report and its implications for fresh produce, as will other food groups, such as milk," Ms. Means added. The fact that perchlorate has been found in 35 states and more than 11 million people have perchlorate in their drinking water at concentrations of four ppb or higher shows the issue is more widespread than was thought, she said.
The issue has caught the attention of Capitol Hill. U.S. Sen. Diane Feinstein (D-CA), who plans to introduce comprehensive legislation to address perchlorate contamination, urged EPA to issue a final drinking water standard.
In the meantime, some environmentalists charged the White House with interfering with the federal report and pressuring the committee to downplay the health effects of perchlorate. The Natural Resources Defense Council said White House and Pentagon officials tried to limit the scope of the NAS report and select its panelists.
In a Jan. 11 press conference, the NAS said that the study was the focus of the most rigorous peer review process and that the panel included top pediatricians and thyroid experts with more expertise "than any agency could afford."
The issue has become a lightning rod for environmentalists, health officials, defense contractors and Pentagon officials who are all battling over the appropriate drinking water standard and what could become a costly cleanup of water supplies that have become polluted with the rocket fuel byproduct. While experts agree that large doses of perchlorate can hamper the thyroid gland?s normal functions, the debate over low doses has pitted federal agencies against one another.
Specifically, NAS found that the most sensitive populations could safely ingest 0.0007 milligrams per kilogram of body weight of perchlorate on a daily basis. This is more than 20 times the reference dose proposed by EPA in its draft risk assessment, which has been driving EPA towards a one part per billion drinking water standard. NAS officials refrained from speculating on a new drinking water level as health officials must weigh a variety of factors " not only science " to agree on an appropriate number, the panel said.
EPA and NAS arrived at much different safety levels by disagreeing over the use of animal data. EPA predicted that exposure would lead to thyroid tumors, as they had in a few studies involving rats. But NAS said that perchlorate exposure was unlikely to lead to thyroid tumors in humans because people are much less susceptible than rats to disruption of thyroid function or formation of thyroid tumors.
The scientific debate is of great concern to produce growers as the Food & Drug Administration has been finding trace amounts of perchlorate in lettuce and milk, and the agency has yet to announce its results for tomatoes, carrots, cantaloupes and spinach.
?The National Academy of Sciences report is another valuable tool to help us better understand the impact, if any, of perchlorate," said Hank Giclas, vice president of science and technology for Western Growers Association. "The safety of our food supply is the highest priority of Western Growers, the farmers and all those who are involved in the production, processing and delivery of fresh fruits, nuts and vegetables.
?We employ many practices, such as verification of quality water sources, good agricultural and manufacturing practices, and compliance with all local state and federal regulations, to ensure our food supply is safe," continued Mr. Giclas. "We will fully review the findings of the National Academy of Science committee to determine what further actions growers, packers and shippers should take to further enhance the safety of our products."
?The most important thing to note is that FDA has indicated consumers should eat plenty of fruits and vegetables and should not change eating habits because of perchlorate," said Kathy Means of the Produce Marketing Association. "I don?t expect this report to change FDA?s stance on this, but we will be interested in hearing that agency?s reaction. "Certainly numbers for water do not equate to numbers for food, and we?ll need to evaluate the report and its implications for fresh produce, as will other food groups, such as milk," Ms. Means added. The fact that perchlorate has been found in 35 states and more than 11 million people have perchlorate in their drinking water at concentrations of four ppb or higher shows the issue is more widespread than was thought, she said.
The issue has caught the attention of Capitol Hill. U.S. Sen. Diane Feinstein (D-CA), who plans to introduce comprehensive legislation to address perchlorate contamination, urged EPA to issue a final drinking water standard.
In the meantime, some environmentalists charged the White House with interfering with the federal report and pressuring the committee to downplay the health effects of perchlorate. The Natural Resources Defense Council said White House and Pentagon officials tried to limit the scope of the NAS report and select its panelists.
In a Jan. 11 press conference, the NAS said that the study was the focus of the most rigorous peer review process and that the panel included top pediatricians and thyroid experts with more expertise "than any agency could afford."
