An environmental organization is asking the government to test
produce from all areas at risk of perchlorate contamination
– including Santa Clara County – after a test of supermarket
lettuce bought in Northern California found concentrations of the
chemical in produce that likely originated in Southern California
or Arizona.
Four of 22 samples of winter lettuce purchased at area supermarkets contained measurable perchlorate levels
SAN MARTIN – An environmental organization is asking the government to test produce from all areas at risk of perchlorate contamination – including Santa Clara County – after a test of supermarket lettuce bought in Northern California found concentrations of the chemical in produce that likely originated in Southern California or Arizona.
In what are reportedly the first-ever tests for the chemical in retail supermarket produce, a Texas Tech University study commissioned by the Oakland-based Environmental Working Group found levels of perchlorate that exceeded government recommended levels for drinking water in a “significant minority” of samples taken off grocery store shelves.
While they admit the sample size of the test was relatively small, the group thinks the results are important enough that it is asking the U.S. Food and Drug Administration to test produce from all areas at risk of perchlorate contamination.
The group also is asking the government for more strict perchlorate safety standards that would take into account potential exposure from both food and water.
“I think the study is further confirmation that any lettuce grown in an area where water is contaminated with perchlorate could itself be contaminated with perchlorate,” said Bill Walker, the Environmental Working Group’s West Coast vice president. “We’re thinking the FDA should do a much more widespread and definitive study, not only of Imperial Valley lettuce but obviously lettuce in Santa Clara County and other areas where we know there’s contamination and there are vegetables being grown.”
The average American consumed 33 pounds of lettuce in 2000, according to the EWG report. Lettuce accounts for roughly 4 percent or $12 million of Santa Clara County’s $288 gross agricultural production in 2001, the last year the values were tallied.
Leaf lettuce was the eighth-highest crop by value in Santa Clara County in 2001 with an estimated gross value of $6,553,000. Head lettuce was 10th at an estimated value of $4,066,000. Romaine lettuce rang in at $1,698,000.
The EWG study found four of 22 samples of winter lettuce purchased at seven Northern California supermarkets in January and February of this year contained measurable perchlorate levels.
The samples included pre-packaged and head lettuce crops, adult and baby greens, organic and conventional lettuces from several different distributors. Specific brands and supermarkets weren’t released in order to avoid tainting a particular producer.
The group admitted it can’t be certain about where the lettuce was grown or what the levels of perchlorate were in the water used to grow them, but it suspects most came from either Imperial County in Southern California and from Yuma County, Ariz.
Most of the cropland in those areas – which supply the majority of the nation’s winter lettuce crop – is irrigated by water from the Colorado River, which is contaminated with perchlorate from an old factory near Las Vegas and has shown concentrations of 4 to 16 parts per billion, according to the group.
The average amount of perchlorate in the contaminated samples was 70 ppb, meaning a typical one-cup serving would contain four micrograms of perchlorate, the group said. The EPA’s current provisional reference dose for perchlorate in drinking water is 1 microgram per liter, according to the group.
Because detection limits in lettuce are higher than water – at 30 to 40 ppb – it’s also possible that more of the samples were contaminated, officials with the group said.
The state Department of Health Services and the U.S. Environmental Protection Agency are in the process of developing enforceable standards for perchlorate in drinking water.
The Environmental Working Group maintains the standard should be no more than one-tenth of the EPA’s current provisional level.
The federal Food and Drug Administration is reportedly working on protocol to test vegetables for perchlorate. Officials couldn’t be contacted immediately by Monday’s press deadline to comment on the status of those efforts.
“We hope our report spurs them to move swiftly,” Walker said.
Officials with the Santa Clara County Farm Bureau said Monday they had just received the report and were still reviewing it.
While they’re glad research on perchlorate is continuing, officials said it is difficult to compare lettuce to other crops because lettuce has a high water content and does not have the same kind of filtering that other products do – such as orchard trees or animals. Studies also need to illustrate how and if the chemical affects different parts of the different plants.
They hope more comprehensive studies on all different types of food are in the wings.
“I hope there will be other studies done with different crops so we have a good representative sample,” said Jenny Mitdgaard Derry, the bureau’s executive director.
Perchlorate is a by-product from the manufacture of flares, matches, fireworks and, in larger amounts, solid rocket fuel.
A plume of the chemical has spread from an old Olin Corp. highway flare factory in Morgan Hill and contaminated several municipal wells in Morgan Hill, as well as hundreds of private wells south of the city.
According to the California Environmental Protection Agency, scientific studies have suggested perchlorate can disrupt thyroid hormone production. Inhibited thyroid function can result in hypothyroidism and in rare cases, thyroid tumors.
Sensitive populations include pregnant women, children and people who have health problems or compromised thyroid conditions.
The Environmental Working Group is a nonprofit research and advocacy organization that concentrates on toxic chemicals in food, air and water.
