Adjust Font Size :

Perchlorate Issue Is Percolating

As the industry focus shifts to United’s convention in Chicago, it is worth noting that United’s most valuable contribution to the industry is actually dealing with hundreds of issues that the average person in the trade barely hears about. One issue that has percolated for years is the issue of perchlorate.

Perchlorate is commonly found in the environment and known to inhibit thyroid function at high doses. Assessing the potential effect of low-level exposure to perchlorate on thyroid function is an area of ongoing research.

In January of this year, U.S. Senators Diane Feinstein and Barbara Boxer introduced two bills: S.24, the “Perchlorate Monitoring and Right-to-Know Act of 2006” and S.150, the “Protecting Pregnant Women and Children From Perchlorate Act of 2006.” The bills aim to set standards for perchlorate, a chemical used widely in a variety of industrial processes and found in water supplies nationwide. The first bill requires EPA to establish a health advisory and a standard for perchlorate contamination in drinking water supplies by the end of the year. The second bill requires drinking water to be tested for perchlorate and mandates public notice if the chemical is found.

We sent Pundit Investigator and Special Projects Editor Mira Slott out to get an update and learn more about how this issue impacts the produce industry:

Robert Guenther
Senior VP Public Policy
United Fresh Produce Association
Washington, D.C.

Q: What is the status of the perchlorate bills?

A: On April 25, there was a hearing in the house subcommittee on the environment and hazardous material on perchlorate led by Congressman Albert Wynn. [You can listen to the testimony here]. Scientists and federal officials testified but there wasn’t anyone from the industry that spoke.

The bills have been introduced. No actionable moves have taken place on those bills yet. Senator Boxer, being chairman of the senate environment and public works committee, leads many to believe significant action will occur this year.

Q: How could this impact the produce industry?

A: This is a valid issue that has been out there for several years and certainly congressional oversight will be heightened with issues of health and environment in the forefront. More members are interested in this with Democrats under control of Congress. I suspect the Senate will have a hearing in Senator Boxer’s committee. Once oversite hearings are done the next step will be moving through the legislative process. To gain better perspective from a scientific standpoint I recommend speaking with Jim Gorny [Ph.D., Senior VP Food Safety & Technology at United] or Dave Gombas [Ph.D., VP Scientific & Technical Affairs at United].

Mira touched base with Dave to learn more:

Dave Gombas, Ph.D
VP Scientific & Technical Affairs
United Fresh Produce Association
Washington, D.C.

Q: How does the issue of perchlorate affect the produce industry?

A: Perchlorate is an issue primarily generated by contamination of ground water from other sources, such as ammunitions from the Department of Defense.

Once in the water, perchlorate is soluble; it dissolves very well in water so where water goes, perchlorate goes with it. Crops like lettuce, carrots and other produce contain a lot of water. When ground water contains perchlorate, the crops will contain perchlorate as well. When analysis is done of fresh crops, perchlorate will be there.

Q: Is this dangerous?

A: Perchlorate interferes with iodine uptake in the body. This could be a real problem for growing children. Perchlorate interferes with the thyroid. If the thyroid doesn’t work well it has implications for growth. However, Americans tend to have sufficient iodine in their diet from salt and other sources. Experts I’ve talked to so far say that the levels of perchlorate we see today in produce don’t present significant risk to consumers. That doesn’t mean we should ignore perchlorate in the water. It just means that it is not a food safety hazard for virtually all American consumers.

Q: Can the produce industry take steps to reduce the levels of perchlorate in different produce commodities? Will there be new regulations companies will need to follow if the proposed bills become law? And if so, what costs would be involved?

A: It depends on how the legislation reads when and if it is ultimately developed. One thing produce suppliers need to be aware of is that they have no control of perchlorate coming in the water or showing up in vegetables. There is no pre-treatment or cooking technique to eliminate it from the product. Well, I should correct that to say, there is nothing practical a farmer could do today to reduce perchlorate coming into the water or the vegetables.

Studies are showing perchlorate is everywhere. Perchlorate is slowly diluting out across the entire aquifer, many hundreds of miles from the original source.

Q: To clarify, even though perchlorate has become more widespread, the levels in the food supply are safe for the vast majority of American consumers?

A: It is a toxin, so sure there is consumer concern. I’m not a medical doctor, but from the studies I’ve seen, and from the experts I’ve heard from so far, the levels seen do not present health concerns to most Americans with sufficient source of iodine. We need to find out whether the amount of perchlorate is increasing, decreasing or staying the same. We need to keep an eye on how much perchlorate is present in produce items. It is important to remember that perchlorate will be in drinking water, milk, and many food items that contain water. Someone from the CDC could provide you with more information.

Mira goes to CDC for more answers:

Benjamin Blount, PhD
Chief, VOC and Perchlorate Laboratory,
National Center for Environmental Health,
Centers for Disease Control and Prevention
(CDC), Washington, D.C.

Q: Could you tell us about the studies you’ve conducted on perchlorate?

A: CDC last year issued a report on perchlorate, which I co-authored, here, analyzing the effects of perchlorate levels in adolescent and adult men and women living in the U.S.

The research study showed that American women — and especially women with low iodine intake — are at risk of hypothyroidism due to common exposure to the toxin perchlorate. The study was published by the Environmental Health Perspectives Branch (EHPB), National Institute of Environmental Health Sciences, National Institutes of Health, U. S. Department of Health and Human Services.

Q: What were the study’s parameters and methodology? This sounds like cause for concern. Please elaborate.

A: As an exposure-assessment scientist, my area of expertise, the key issue is how much of the chemical someone’s been exposed to and if that exposure could be associated with any change in their health.

We’ve developed new ways of measuring exposure to perchlorate through urine samples.

For most people, perchlorate intake goes into urine.

We looked at 2,820 U.S. residents ages 6 and older in 2001 and 2002 and every urine sample had measurable samples of perchlorate, which indicated it was wide spread. Children had higher levels of exposure than adults. We’re not sure if that is because children eat different foods or if it’s because of more foods per body weight. We’re not sure why that is.

The next thing we did was compare the level of perchlorate exposure we found with the dose of perchlorate the Environmental Protection Agency says is ok. That’s called a reference dose, an amount estimated to be without appreciable risk of adverse health effects during a lifetime of exposure.

What we found when we estimated levels is that the vast majority of people’s doses were lower than the EPA dose.

A second aspect to this was the population we studied. Some of these individuals also had their thyroids tested to gauge how well their thyroid glands were working.

The group was composed of 2,299 men and women, ages 12 and older. What we found there, females, especially with lower iodine intake, had higher levels of perchlorate in urine. They tended to have changes in their association between higher levels of perchlorate in urine and decreased thyroid function, especially those with lower iodine intake.

Some were more susceptible to perchlorate’s toxicity, especially those that didn’t get enough iodine in their diet.

I didn’t use the term cause and effect. We don’t know perchlorate is causing this. We can only say the females that had higher perchlorate levels had lower thyroid function.

Q: How did these results compare to earlier studies you’ve conducted?

A: Earlier, I was involved in a Chilean study that looked at perchlorate exposure in pregnant women. In that study, we didn’t find an association between exposure and any changes in thyroid function.

Q: Why the different results?

A: We’re still studying this. I suspect several factors contributed to different findings. The Chilean population has more iodine in their diet than Americans do. Urinary iodine levels were measured in two studies, with very few of the women in Chile having low iodine levels. In American more than a third had low iodine levels.

The second difference: The Chilean study examined pregnant women. During the pregnancy time, the thyroid is adapting to the forming fetus. In a normal pregnancy, thyroid levels are changing. It becomes a little harder to see the effect that the change in perchlorate could contribute.

The Chilean study involved 180 total women, only three of those had consistent low iodine levels, whereas in our CDC study almost 400 women had low iodine levels.

Q: I thought Americans had a reputation for having too much salt in their diet.

A: A lot of salt is not iodized. Sea salt and kosher salt have almost no iodine. In commercial grade salt, I don’t think any is iodized. Also, a lot of people are cutting down on salt.

Using iodized salt is a way to increase iodine intake. With all things there’s a right amount.

With a small amount of iodized salt, you can certainly increase your iodine intake. Other foods like milk and some types of seafood are also good. FDA has support information on this.

Q: What’s the bottom line in terms of the dangers current perchlorate levels in foods pose to the American public?

A: A number of groups have measured perchlorate levels in milk and other dairy products. We found perchlorate exposure is widespread in the U.S. We found that a sub population of females with low iodine intake is potentially susceptible to the dangers of perchlorate, where we’ve seen a change in thyroid levels. The magnitude of this association is small to moderate from a clinical standpoint. Our finding predicts a perchlorate effect that is of small to moderate magnitude clinically relative to normal variation in thyroid function.

We certainly have a number of further studies planned to confirm the incidents and magnitude of perchlorate exposure in the population, and to look at thyroid function association in subsequent studies.

Mira also followed up with Charles Sanchez of the Yuma Ag Extension Service. Mira first interviewed Charles for a Pundit Special Science Report examining food safety vulnerabilities in Yuma and Salinas and the science of waterborne bacteria. You can read the extensive three-part series here.

Charles Sanchez
Director and Professor of Soil,
Water and Environmental Sciences
University of Arizona
Yuma Ag Extension Service


Q: Since we spoke about perchlorate issues several months ago, two bills to regulate perchlorate levels have emerged in Congress. Could you share your view on this latest development?

A: Perchlorate is not a problem for produce in Arizona. Amounts are very low relative to the reference dose established by the National Academy of Sciences. As I discussed in our original interview, there are trace levels of perchlorate in the Colorado River, but the resulting levels we’ve measured in lettuce are a small fraction of the reference dose, and in spinach are still less than 10 percent of the reference dose.

I also wanted to reinforce my point in that interview regarding the effective clean up several years ago of a perchlorate problem at a site near Las Vegas in Henderson. Perchlorate had leaked out from a plant through Lake Mead to the Colorado River. The contamination could have been there a long time, but we only had the technology a few years ago to detect it at the parts per billion level.

Bioreactors were installed to clean up the spills and reduced the loads considerably. Bioreactors have micro organisms in them that convert the perchlorate to chloride. The process renders a potential toxin to a benign substance. In fact, due to the bioremediation near the site of the contamination, the levels of perchlorate in the river have dropped substantially over the last few years.

However, a recent report released by CDC found levels below the reference dose affected thyroid hormone levels in women. This is a report that has motivated United States Senator Barbara Boxer. The Democrats have taken control of key committees and Senators Diane Feinstein, Boxer and others have a perchlorate agenda.

The bills are not a bad thing. Perchlorate contamination probably should be cleaned up. I don’t think anyone is against a clean up. My point is that the levels we are finding in vegetables in Arizona and southern California are below levels considered harmful using the best available science we have today. The CDC findings and other epidemiological studies in Chile show additional research is needed.

Chile has natural levels of perchlorate. The study picked three cities; one below levels of detection of perchlorate, one between 5 and 10 parts per billion of perchlorate, and the third city with levels 100 parts per billion. In examining the results of perchlorate in pregnant women, the study found no significant differences in hormone levels.

There were key differences between the two populations in the CDC study and the one done in Chile. Generally, the women in Chile were exposed to higher levels of iodine. Iodine is a competitive inhibitor of perchlorate and therefore perchlorate is less likely to impair the thyroid. Most Americans get enough iodine, but people have reduced sodium intake of iodine for health reasons. Fast food restaurants such as McDonald’s now use non-iodized salt.

Q: Doesn’t the CDC report raise a red flag on potential dangers of perchlorate in certain subpopulations?

A: CDC’s report indicates we need to do more work in this area. Perchlorate is found all across the United States, not just in California and Arizona. We also found perchlorate in many other places. FDA has found it in milk all over the country. We sampled a lot of dairies in the Southwest, California and Arizona, analyzing the drinking water of cows and resulting milk samples. I haven’t collected a milk sample to date that doesn’t have perchlorate in it. I also investigated perchlorate levels in lettuce and found no concerns.

There are perchlorate spills around the country and no one objects to clean up. But I would object to any reference that produce in Arizona isn’t safe to eat because of it. This issue will flare up again because Democrats taking power want to pursue it.

To some extent this is an environmental issue, but then, as we referenced here, one way of thinking about E. coli 0157:H7 is as a kind of pollution from cattle ranches and dairy herds. And one policy response would be an effort to restrict and remediate the effects of that pollution.

Still, although this issue is mostly below the radar right now, the industry shouldn’t take much solace from the fact that most research seems to indicate that negative effects, if any, are confined to certain sub-segments of the population. The serious effects of most foodborne illness also are confined to certain vulnerable segments of the population. Yet this doesn’t prevent foodborne illness from being a major issue.

In light of all the industry efforts to increase produce consumption among children, we need to be especially mindful of what research can tell us in this area. Very little research is ever done on what is safe for small children, so we are often extrapolating from adult studies.

The poignant story of Kyle Allgood, the 2-year-old from Idaho whose mother tried to help him by adding healthy greens to a fruit smoothie, was also just about the most damaging thing that could happen to the produce industry because it placed in the minds of consumers negative thoughts about giving produce, healthy greens at that, to young children.

Perchlorate is a chronic health issue, so we won’t have the drama of a spinach crisis. It is wide-spread in other foods so it is not a produce- specific issue.

Yet, things have a logic of their own and if Senators Boxer and Feinstein are successful in persuading their colleagues that perchlorate should be monitored in drinking water, surely it won’t be long before irrigation water is monitored as well. And then food itself will need to be tested.

And it is difficult to know if this is appropriate or not.

So if at United you see Dr. Gorny or Dr. Gombas, shake their hands and thank them for figuring it all out. This kind of quiet, but important. work is why, along with WGA’s Hank Giclas, we gave them The Perishable Pundit’s Unsung Heroes Award.

Print Friendly, PDF & Email

The Latest from Jim Prevor's Perishable Pundit