A new report that found significant levels of perchlorate in
breast milk in women nationwide will get serious consideration from
the state agency charged with ensuring the public health goal for
contaminant of the potentially toxic compound, a spokesman for the
federal Office of Environmental Health Hazards Assessment said
Thursday.
A new report that found significant levels of perchlorate in breast milk in women nationwide will get serious consideration from the state agency charged with ensuring the public health goal for contaminant of the potentially toxic compound, a spokesman for the federal Office of Environmental Health Hazards Assessment said Thursday.
“In general, with drinking water contaminants we try to stay up on the latest science, and that’s especially true with perchlorate because there’s a great deal of interest and there’s a lot happening,” spokesman Allen Hirsh said. “We definitely want to get a handle on what the study means.”
The perchlorate contamination in San Martin and Morgan Hill has been linked to a former road-flare factory in Morgan Hill owned by Olin Corp. Much of the contamination in Southern California has been linked to the defense industry. Perchlorate also is an oxidizing ingredient in rocket fuel.
Released earlier this week by doctors at the Institute of Environmental and Human Health at Texas Tech University, the study found perchlorate in breast milk in each of 36 samples from women in 18 different states, including California. The milk was contaminated at levels from 0.6 to 92.2 parts per billion, at an average of 10.5 parts per billion. About a year ago, OEHHA set California’s public health goal at 6 parts per billion.
Part of the state Environmental Protection Agency, OEHHA has been considering altering the goal in response to a January report issued by the National Academy of Sciences and lobbying from a chorus of environmental advocates who wish to see the goal revised downward.
The NAS report did not set a drinking water standard, issuing instead a reference dose that it described as being the safe daily intake for an adult male of about 155 pounds. That translates to a standard of roughly 14 parts per billion for water and 23 parts per billion including food consumption. The standard would be lower for children. Olin currently provides bottled water for residents whose water tests at or above 4 parts per billion.
The Morgan Hill City Council has directed city staff to shut down municipal wells when perchlorate reaches the detect level of 4 ppb. The city has installed treatment systems on the Nordstrom and Tennant wells to ensure that city water is below that level.
A sodium compound, perchlorate inhibits the thyroid gland’s ability to produce hormones by interfering with iodide uptake and has been shown to hamper brain development in baby rats. Nursing mothers are the only source of iodide babies need for proper thyroid function. Texas Tech researchers wrote that its results make it “obvious that the NAS safe dose … will be exceeded for the majority of infants, and some will also exceed the … dose at which brain morphology changes were observed in nursing rat pups.”
The rat data touted by the Texas Tech study was, however, dismissed by NAS scientists. Dr. Richard B. Johnston, chairman of the NAS committee, said at the time the committee was “insecure about extrapolating from rats.” because their thyroids function differently from humans.
Dr. Marty Fenstersheib, health officer for Santa Clara County, said Thursday that Texas Tech’s study sample is too small to draw broad conclusions, but that it should be taken seriously by people living in contaminated areas.
Gilroy Dispatch reporter Matt King can be reached at mk***@************ch.com or 847-7240.
