How to Limit Pesticide Exposure

Today, we look at the body of evidence that links pesticides to serious health problems.

And we start with an episode guest-hosted by Dr. Kristine Dennis, our Senior Research Scientist, who has been researching and scripting new video topics. In this video, Kristine delves into the association of vegetarian diets and hypospadias birth defects to see if it holds up in the light of new research.

In 2000, a study found that a vegetarian diet during pregnancy was associated with hypospadias, a specific birth defect of the penis. The authors suggested that it may be due to the greater exposure to phytoestrogens, which are found in soy foods. But if you look globally, while there is an extraordinarily high prevalence in North America and Europe, it’s extremely low in a country like Japan, which has the highest per capita soy intake in the world. In fact, in Japan, a low maternal intake of soy phytoestrogens has been associated with elevated risk of hypospadias; so, if anything, soy may be protective.

If soy foods aren’t the hormone disrupters, what in a vegetarian diet might be? Well, occupational exposure to pesticides is associated with higher risk; so, might low-level pesticide exposure among those eating more fruits and vegetables—like vegetarians—help explain it? If you randomize people to a more plant-based Mediterranean diet, you see a large increase in the amount of pesticides flowing through their body, though, of course, if you put them on a Mediterranean diet with organic fruits and vegetables, you see a 90 percent drop in pesticide exposure.

So, does organic food consumption during pregnancy reduce hypospadias risk? Apparently so, cutting the odds about in half––particularly when it comes to choosing organic vegetables and dairy, though the only other study to look at organic food choices and hypospadias found the risk associated just with conventional high-fat dairy products.

It isn’t all or nothing. Even if only two-thirds of your produce is organic, that can significantly reduce pesticide exposure. But the benefits of consuming conventionally-grown produce likely outweigh any possible risks from pesticide exposure, so concerns over ingesting pesticides should never discourage fruit and vegetable intake. In the United States alone, if you add up all of the fatal cancers, strokes, heart attacks, and other deaths that could have been averted simply by eating more fruits and vegetables, it comes out to nearly 450,000 deaths every year. That’s how powerful produce can be. But might one of the downsides be this hypospadias risk?

Despite their high plant consumption, vegetarians may be less exposed to conventional pesticides, but that’s because of their greater propensity to choose organic produce. Now, the researchers only considered the pesticides in plant foods, not animal products, and even for conventional insecticides, animal products are main contributors to exposure. Additionally, persistent pesticides, such as organochlorine pesticides like DDT, are concentrated in fish, other meats, and dairy; so, it’s no surprise that the blood of strictly plant-based eaters ends up significantly less polluted. It may not just be from the lower level of intake, though; high-fiber diets can bulk up the stool and glom on to pesticides and flush them away.

In the end, the hypospadias issue may be another example of the stroke scare. Dr. Greger did a whole series covering potential explanations why a study had found higher stroke rates among vegetarians, but then half a dozen other studies found lower rates of stroke, if anything, across the board.

The original hypospadias study looked at about 50 cases. Twelve years later, a study that looked at 1,250 cases was published and found zero increased risk among vegetarian mothers.

In our next story, researchers measure the impact of eating organic on the level of pesticides in our children.

Produce can be contaminated by manure runoff, and conventional produce may be contaminated with pesticides. We’ve known for years that the 800 million pounds of pesticides used annually in the United States – the herbicides, fungicides, insecticides – have clear-cut adverse effects on farm workers and their families. That’s uncontroversial. We can even do what are called hand-wipe studies to actually measure the pesticides in the hands of kids in California’s Central Valley, wherethe planes come down and spray this fog. How much exposure urban and suburban children are getting from food, however, has been unclear, until now. Twice daily urine samples were taken from 3- to 11-year-olds for more than a year to see how much pesticide is flowing through our kids. These children were nowhere near farms, or fog-spraying planes. And to single out pesticides that were coming from the diet, as opposed to a lawn treatment or something, for two weeks of the year, the kids were put on organic diet. Guess which two weeks those were? So, the two times during the year when they ate organic foods, there were undetectable, or nearly undetectable, pesticide residues in their urine, while their little bodies were basically swimming in it the rest of the year.

In my 2000 update, I told everyone about this disturbing study. Vegetarianism during pregnancy associated with having sons with a specific birth defect of the penis called hypospadias. They thought it might have something to do with the phytoestrogens in soy, but that didn’t make any sense since Japan, with the highest per capita soy consumption in the world, did not have high rates of the defect. I guessed that it might be low vitamin B12 levels leading to high homocysteine, which has been related to other birth defects, but we were all wrong.

Finally, though, the mystery seems to have been solved. The researchers reanalyzed the data for clues as to what could be found in the diets of vegetarians compared to meat eaters—other than more good things, like more fruits and vegetables. Unless, there is an endocrine-disrupting fungicide, called vinclozolin, that is sprayed on most of our conventional crops, which we now know causes hypospadias. So, researchers went back and split up the vegetarian moms into two groups: those eating organic produce, and those eating conventional produce. And, while the vegetarian women eating conventional produce during pregnancy had, indeed, higher birth defects rates, there was not a single case in the organic group.

So, it seems the hypospadias wasn’t due to vegetarian diets; it was that they were exposing their fetus to more pesticides. Can’t we just rinse our produce off? Well, it’s better than nothing, but this new study looked at three pesticides on apples. Levels start out at 100%. Rinsing seems to take off only about 15% of the pesticides. The only way to really cut down our dose is to peel the apple, eliminating about 85% of the pesticides—but also eliminating much of the nutrition.

So, eat organic foods whenever possible. Organic produce has more vitamins, more minerals, tastes better, stores better, and you get to not be complicit in poisoning farm workers and their families.

Finally today, how can we avoid the breakdown product of pesticides that may increase the risk of Alzheimer’s disease?

Although there is a growing list of Alzheimer’s disease susceptibility genes, even if you put them all altogether, they account for less than half of all Alzheimer’s cases. The single most compelling piece of data on the potential control we have over the disease is the fact that if you have identical twins, with the exact same genes, even if one gets Alzheimer’s, the other usually does not. So, we have to think about all the other contributing factors beyond just genetics.

In my video on pesticides and cancer, I talked about this study. There’s a list of chlorinated pesticides, including DDE (a metabolite of DDT), that are classified by the EPA as probable human carcinogens. But in the study, blood levels of DDE and others were associated not with increased cancer mortality, but increased risk of other-cause mortality. This led researchers to speculate this may be due to an associated increased risk of diabetes or dementia. I’ve talked previously about the diabetes link. What about dementia? “Elevated Serum Pesticide Levels and Risk for Alzheimer Disease.”

A research team at Rutgers found significantly higher blood levels of DDE in Alzheimer’s disease patients compared to controls, and autopsy studies show blood levels are a good proxy for brain levels. Those with the highest levels were at about four times the odds of being demented with Alzheimer’s. And in a petri dish, DDE increases amyloid precursor protein levels in human brain cells, providing a potential mechanism.

Put all these studies together, and there does indeed seem to be a link, consistent with data showing about a doubling of risk for developing dementia among those acutely pesticide-poisoned. Among U.S. elders, DDT and its breakdown product DDE are also associated with increased risk of cognitive decline in general.

DDT was extensively used in the United States from the 1940s through the 1960s. At its peak, we were churning out 180 million pounds a year. And it’s still in our bodies to this day, contaminating the bloodstreams of more than 90 percent of Americans, and DDE, the pesticide linked to quadrupling the odds of Alzheimer’s, were at the highest levels.

It’s still in our bodies because it’s still in the food supply. In my last video on the topic, I noted that the levels of DDT, DDE, and other banned pesticides and pollutants were much lower in the breast milk from a vegetarian mother compared to breast milk of her non-vegetarian sister. And the largest difference was noted for DDE, which was four times lower in the vegetarian sister.

This is what you see across the board for these kinds of pollutants. Food samples were collected from supermarkets across the U.S. Here’s what they found for dioxins and PCBs in beef, chicken, pork, processed meat, eggs, fish, all plant-foods put together, and dairy products. These toxins build up in the food chain; so, it makes sense that the most contaminated foods are meat, fish, and dairy products. There are 5 to 10 times higher levels in meat, eggs, fish, and dairy than what we find in plant foods. And unfortunately, cooking doesn’t destroy pollutants like DDE—in fact it may make them even more concentrated. And this is for a pesticide that may increase the risk of Alzheimer’s disease as much as if you carried the so-called Alzheimer’s gene APOE e4.