Study challenges thyroid concern
PERCHLORATE: The researchers say they did not find Redlands' infants to be at greater risk.
Friday, March 5, 2004
By David Danelski
Laboratory studies have found that perchlorate - the rocket-fuel chemical that has contaminated some Inland water supplies - impairs thyroid function and could compromise fetal development.
But the research has not proven that small amounts in drinking water are harmful.
A Lockheed Martin Corp.-funded study published in October concluded that perchlorate pollution in Redlands and Mentone drinking water did not result in higher incidences of thyroid problems in babies born during between 1983 and 1997.
Challenges Arizona findings
The conclusion is contrary to results of a 2000 study by Arizona state health officials. That research found statistically relevant changes in hormones that affect thyroid glands in babies born in Yuma, where drinking water is contaminated by perchlorate.
Lockheed undertook its research in response to lawsuits filed by Redlands-area residents who allege that perchlorate in their drinking water made them sick. The chemical leaked from a former Lockheed rocket factory in Mentone, causing a stream of underground pollution that has invaded water supplies for Redlands, Loma Linda and Riverside.
Scientists hired by Lockheed examined state health records for newborns and found only two cases of primary congenital hypothyroidism in the Redlands-Mentone area. Four or five cases would be expected based the number of births.
Hypothyroidism is a serious condition in which the thyroid gland doesn't produce enough hormones, causing body functions to slow down.
The study did find higher levels of a thyroid-stimulating hormone in the Redlands newborns, but the authors concluded that the hormone difference between those infants and babies statewide was not statistically significant.
Higher levels of thyroid-stimulating hormone signal that the thyroid gland is under stress and might not be working properly. Animal studies have found that more of the hormone is produced when the thyroid is exposed to perchlorate.
More than 15,300 babies were born in the Redlands-Mentone area during the 15-year period, but not all were screened for thyroid hormones. About 2.1 percent of the 2,099 babies who were screened had elevated levels of the hormone. The rate for Riverside and San Bernardino counties and all of California were, respectively, 1.9 percent and 1.5 percent.
Study co-author Michael Kelsh of Menlo Park-based Exponent Inc. said the difference in Redlands can be explained by a disproportionate number of babies whose blood was tested within 18 hours of birth. The amount of thyroid-stimulating hormone naturally increases during this time as the baby responds to cooler temperatures outside the womb, Kelsh said. Findings are more reliable if blood is tested at least 18 hours after birth, he said.
The Lockheed results bolster industry and Department of Defense assertions that low levels of perchlorate in drinking water do not pose health risks. The company spent about $500,000 on the study, a Lockheed representative said.
Unlikely to settle debate
The findings are not expected to end debate over the contamination in hundreds of wells, the Colorado River and the lettuce crops it irrigates.
Annie Jarabek, who has overseen the U.S. Environmental Protection Agency's health-risk assessments for the chemical, said the Lockheed study and earlier research like it are not sufficient to tell whether the concentrations found in drinking-water supplies are safe.
An inherent problem with such studies is that each individual's exposure to the chemical is unknown, Jarabek said by telephone.
The Lockheed results are similar to other industry studies done in Nevada and Chile.
But the state-funded Arizona study found that babies in Yuma, where drinking water has low levels of perchlorate, had higher levels of thyroid-stimulating hormones when compared with newborns in Flagstaff, where the tap water does not contain the chemical.
Ross Brechner, the lead author of the Arizona study, said by telephone that additional independent studies need to done.
Gary Praglin, the attorney for 14 Redlands-area residents who are suing Lockheed, said he questions the research's objectivity.
Lockheed Martin has a huge financial interest in the issue because it faces lawsuits, he said. He added that one of the co-authors, UC Berkeley epidemiologist Patricia Buffler, has earned $400 an hour from Lockheed as an expert witness in the case. She was paid about $50,000 for her work on the study, according to Lockheed.
Kelsh said the Lockheed study is objective and answers questions about newborn thyroid health in Redlands.
"It's the real-world experience of this population," he said.
Buffler and Kelsh said the company did not sway their findings. They also said the research passed the muster of peer review by other scientists, who agreed it is valid.
Reach David Danelski at (909) 368-9471 or by e-mail at email@example.com.
Reprinted with permission from .