News Coverage
Perchlorate detected widely in mother's milk
Published February 23, 2005
A study published Tuesday found the rocket fuel chemical perchlorate in all human milk samples collected from women in 18 states, raising new concerns about the federal government's efforts to determine a safe level in drinking water.
The researchers calculated that most of the babies whose mothers gave samples are consuming more perchlorate than the National Academy of Sciences recently found is safe.
The lead author of the study, published in the online edition of Environmental Science & Technology, said women shouldn't stop breastfeeding.
"It's something that may have been around for 50 years, and we just now found it," said Andrea Kirk, a doctoral student in environmental toxicology at Texas Tech University in Lubbock.
"It may be in formula, also," she said.
The U.S. Environmental Protection Agency is considering regulating perchlorate because certain amounts of the chemical can impair the thyroid gland's ability to produce hormones that fetuses and babies need for proper neurological development.
The Texas Tech scientists collected samples from 36 lactating volunteers in 2003 and 2004. The women were recruited by word of mouth and a notice posted on www.mothering.com , a website of Mothering maternity magazine. Samples were frozen and shipped to researchers.
Perchlorate concentrations in the breast milk ranged from 1.4 parts per billion to 92.2 parts per billion, with an average of 10.5 parts per billion. By comparison, California last year set a public health goal of six parts per billion in drinking water.
Like an earlier study of cows' milk by the U.S. Food and Drug Administration, the perchlorate contamination was detected in samples collected nationwide. The concentrations in breast milk, however, were five times higher than in cows' milk samples analyzed by the Texas researchers.
Food May Be Source
They found no correlation between contamination in breast milk and perchlorate concentrations in tap water or bottled water used by the nursing mothers. Food may be a major source of the chemical, the researches wrote.
Peggy O'Mara, the editor, publisher and owner of Mothering magazine, said the problem isn't breast milk.
"Breast milk is always the best choice," O'Mara said. "I wonder of how healthy the environment is if these chemical are showing up in breast milk.
"If it is in breast milk, it is in everything."
An EPA analysis issued Friday concluded that 24.5 parts per billion in drinking water is safe for all people.
That was based on a dose per kilogram of body weight found to be safe by a National Academy committee that spent nearly two years reviewing studies about perchlorate's effects on health. The EPA arrived at 24.5 parts per billion by applying the National Academy's formula to a 70-kilogram (about 150-pound) adult who drinks two liters of water a day.
That analysis is controversial within the EPA.
Kevin Mayer, EPA perchlorate coordinator for the Pacific Southwestern states, said his interpretation of the National Academy's work would put the safe level at 4.3 parts per billion for babies because they consume more liquid per unit of body weight than adults do.
"I'm just not able to explain with any clarity from a professional standpoint how the agency arrived at this (24.5 ppb) conclusion," said Mayer, perchlorate coordinator for more than seven years.
But Bill Farland, an acting deputy assistant administrator at the EPA's Office of Research and Development in Washington, D.C., said basing the safe dose on an adult's weight was appropriate because the most sensitive population is fetuses of pregnant women who have thyroid problems. The safe dose is based on the mother's weight.
Babies More Resilient
Babies are more resilient to perchlorate exposure than such fetuses, Farland said in a telephone interview.
"They can clear the chemical more quickly," he said.
Farland noted that the standard of 24.5 parts per billion is not binding and is subject to change as more is learned about perchlorate ingestion from food. The chemical also has been in found dairy milk, lettuce and grain, the Texas Tech researchers said.
The EPA will examine the Texas Tech data to determine how much of the chemical nursing babies are consuming, Farland said.
Environmental groups said the Texas Tech study supports their calls for federal and state governments to push for cleanups of perchlorate-contaminated drinking water supplies.
Perchlorate is used in rockets, munitions and road flares. Leaks and spills at factories and military bases have allowed the chemical to enter the lower Colorado River, a major drinking and irrigation water source for Southern California, and several Inland groundwater basins.
About 15 percent of the nation's crops and about 13 percent of livestock use water from the Colorado River, according to the Texas Tech researchers. Contaminated water has been found throughout the nation.
Standards For Infants
Renee Sharp, an Oakland-based analyst with the Environmental Working Group, said the Texas Tech findings should prompt the EPA to revise its analysis of how much perchlorate is safe in drinking water.
"This will practically force the EPA into writing a standard that protects infants -- not just healthy adults," Sharp said. "I will be shocked and appalled if EPA doesn't change that."The National Academy of Sciences report on perchlorate called for more research on how the chemical affects breast tissue.
Breast and thyroid cells both have microscopic pumps, called sodium iodide symporters, that bring iodide into the cells. In the thyroid, the iodide helps make hormones needed for fetal development.
In the breast tissue of lactating women, iodide goes into the milk for the thyroid of the feeding baby, said Gregory Brent, a UCLA medical school professor and member of the National Academy perchlorate committee.
Studies on mice could answer questions about whether perchlorate impairs movement of iodide through breast tissue, Brent said.
Kirk, of Texas Tech, said her study found lower levels of iodide in the breast milk samples with the highest levels of perchlorate. Kirk and the other researchers said pregnant and lactating women might need to increase their intake of iodine to compensate for perchlorate.