Why are we poisoning ourselves?

Americans banned DDT in 1972 and PCBs a few years later. We pat ourselves on the back for banning these and other toxic chemicals, but should we? Recent research suggests that though they were banned forty years ago, they are still making us sick.

Although these chemicals were banned, the chemical industry continues to churn out new products about which we know little. Will we find out decades later that these new chemicals are just as likely to poison us as their predecessors? The history of their predecessors suggests that is a likely outcome.

Living with the consequences of our folly

The National Research Council recently published a report (1) that informed us that at least 126,000 sites throughout the country have contaminated groundwater that requires remediation. About 10% of those sites are considered “complex” which is a euphemism for the fact that the technology required to clean them up does not presently exist, meaning that restoration is unlikely to be achieved in the next 50 to 100 years. The report estimates the cost of cleaning up these sites will be from $110 billion to $127 billion. However, the report also acknowledges that both the estimate of the number of sites and the cost of the clean up are probably underestimates.

What are the consequences of living with toxic chemicals? Researchers at Brown University tested the blood of over 3,000 women between the ages of 16-49 for levels of mercury, lead, and PCBs. These three chemicals are known to harm brain development of fetuses and babies. The sample was designed to represent the national population of 134.4 million women of childbearing age. Here’s what they found:

  • “Nearly 23 percent of American women of childbearing age met or exceeded the median blood levels for all three chemical pollutants.” (2)
  • “All but 17.3 percent of the women aged 16 to 49 were at or above the median blood level for one or more of these chemicals, which are passed to fetuses through the placenta and to babies through breast milk.” (2)
  • “As women grew older, their risk of exceeding the median blood level in two or more of these pollutants grew exponentially to the point where women aged 30 to 39 had 12 times greater risk and women aged 40-49 [born before these chemicals were banned] had a risk 30 times greater than those women aged 16 to 19.” (2)
  • “Fish and alcohol consumption also raised the risk of having higher blood levels. Women who ate fish more than once a week during the prior 30 days had 4.5 times the risk of exceeding the median in two or more of these pollutants.” (2)
The body burden of multiple pollutants
The body burden of multiple pollutants

While these findings are horrifying, they pale in comparison to the stunning finding that “One risk factor significantly reduced a woman’s risk of having elevated blood levels of the pollutants, but it was not good news: breastfeeding. Women who had breastfed at least one child for at least a month sometime in their lives had about half the risk of exceeding the media blood level for two or more pollutants. In other words, …women pass the pollutants that have accumulated in their bodies to their infants.” (2)

This particular study emphasizes the consequences of these pollutants for the children of the women who were tested. What about the women themselves? Surely these pollutants are also affecting their health and well-being. We turn to an outstanding book—Living Downstream– by an ecologist and cancer survivor (so far) for an answer to this question.(3)

First we must acknowledge how little we know about the connection between chemical pollution and its consequences to our health. The damage being done to our bodies by pollutants is not immediate nor is our exposure usually quantifiable which makes cause and effect very difficult to prove. Circumstantial evidence of the connection is therefore easily dismissed as anecdotal: women born in the United States between 1948 and 1958 had almost three times the rates of breast cancer in 1997 than their great-grandmothers did when they were the same age. Coincidentally, pesticide use in the United States had doubled between 1952 and 1997. (3, page 13)

Ironically, although DDT and PCBs were banned forty years ago, the connection between breast cancer and these pesticides was not discovered until after they were banned. The first study was conducted 4 years after DDT was banned on only 14 women with breast cancer. Significantly higher levels of DDT and PCBs were found in their tumors than in the surrounding healthy tissues. It took another 17 years to replicate that study on a statistically significant number of women: 14,200 women in New York City who had mammograms. The 58 women in that sample who were diagnosed with breast cancer had higher levels of DDT and PCB in their blood than women without breast cancer. (3)

It took nearly 50 years to prove that women with breast cancer have higher levels of DDT and PCB in their bodies than women without breast cancer. How long will it take us to learn what damage we are doing to ourselves with the pesticides that we are using now?

We aren’t testing for chemical pollution

Bacterial pollution at Pine Lake, San Francisco.  February 2012
Bacterial pollution at Pine Lake, San Francisco. February 2012. Courtesy Save Sutro

In San Francisco, the Department of Public Health tests the water bodies in the city for bacteria. In February 2012 they closed Pine Lake to the public because of bacterial levels. This incident prompted us to ask about San Francisco’s testing of water bodies. We learned that testing for bacteria is the ONLY test conducted in San Francisco. The watershed of Twin Peaks and Glen Canyon into Islais Creek was sprayed with pesticides over 30 times in 2011 by the Natural Areas Program, yet the water in the creek was not tested for pesticide levels. Islais Creek flows into the bay.

The need for more testing of water bodies was recently recognized by the European Science Foundation. (4) They conducted a poll of 10,000 citizens from 10 European countries which found that pollution is the top concern of the public among all concerns regarding the marine environment.

The public has good reason for their concern. There are presently about 30,000 chemicals available on the European market with production volume exceeding one ton per year. The volume of these chemicals entering rivers, streams, estuaries, and seas is increasing and potentially damaging marine organisms, ecosystems, and processes. Yet the testing of waters for these chemicals lags far behind the increasing number of chemicals being introduced to the environment.

We are on a pesticide treadmill

The tests required to put new chemicals on the market are minimal. The testing of pollution levels in the environment is also minimal. Yet, we continually introduce new pesticides about which we know little. Why? We speculate about the motivation for introducing new pesticides into the environment:

  • As the patents on pesticides expire, the manufacturers must introduce new pesticides in order to maintain their profit margins.
  • The longer a pesticide is in use, the more likely its target is to build up a resistance to it. Hundreds of weeds are resistant to available herbicides. Hundreds of insects are resistant to available insecticides.
  • The less the public knows about a pesticide, the less likely they are to be afraid of it and the less likely they are to object to its use..

Why is this issue relevant to Million Trees?

Our regular readers might wonder what this has to do with the mission of Million Trees to inform the public of the destruction of non-native trees for the purpose of creating native plant gardens. The connection is that the use of pesticides by these projects is skyrocketing as the war on non-native plants escalates.

Volume of pesticide use by San Francisco's "Natural Areas Program."  Courtesy San Francisco Forest Alliance
Volume of pesticide use by San Francisco’s “Natural Areas Program.” Courtesy San Francisco Forest Alliance

Those who work for these projects and those who support them defend their use of pesticides in our public parks by telling us they are following the rules, and the rules guarantee no harm will be done by the pesticides. What they don’t seem to understand is that many of the pesticides—and other chemicals—that we now know are harmful to us and the animals that we live with, were legal when they were used. They were legal because we did not know yet that they were harmful.

It took decades for us to understand that the pesticides we were using were harmful. We see no reason to believe that the pesticides we are using now will not also prove to be harmful. By the time we learned how harmful they are, a great deal of damage had already been done. And although many were banned decades ago, they persist in the environment and in our bodies. Therefore, we object to the frivolous use of pesticides in our public parks. Using pesticides for the purpose of killing vegetation solely because it is non-native is irresponsible, given the potential damage they can do to humans and wildlife.


(1) National Academy of Sciences, “Clean-up of some U.S. contaminated groundwater sites unlikely for decades,” November 8, 2012

(2) Marcella Remer Thompson, Kim Boekelheide, “Multiple environmental chemical exposures to lead, mercury, and polychlorinated biphenyls among child-bearing-aged women: Body burden and risk factors,” Elsevier, November 16, 2012

(3) Sandra Steingraber, Living Downstream, Addison-Wesley, 1997

(4) European Science Foundation, “Chemical pollution in Europe’s Seas: The monitoring must catch up with the science,” March 21, 2012

3 thoughts on “Why are we poisoning ourselves?”

  1. http://www.mlive.com/news/grand-rapids/index.ssf/2012/09/no_quick_fix_for_herbicide_dam.html
    The above link describes a lesson I learned in church years ago–“the path to hell is paved with good intentions>’ . It happens in Michigan too.
    In the 40 years I have been farming who would guess that herbicides would end up in our parks and other recreational areas. It is hard to believe. When the experiment goes bad, no one appears accountable.

    Webmaster: Thanks for this link, Ken. Yes, that’s a very familiar story. Imazapyr is now the pesticide being used most frequently by the so-called “Natural Areas Program” in San Francisco. It’s a fairly new pesticide and little is known about it. The federally mandated tests to introduce new products are so minimal that we should not be surprised when the problems weren’t predicted.

    However, in the case of the article to which you provide a link, this should have been predicted. The manufacturer’s label states very clearly that this product should not be sprayed under trees because the pesticide travels from the roots of the plant on which it is sprayed to the roots of anything in the vicinity. In other words, it is mobile in the soil and it is capable of killing a plant when the pesticide travels up from the roots as well as down from the plant into the roots.

    Like the case you tell us about, imazapyr is also being applied by people in San Francisco’s parks who are “certified” to do so. One wonders what that means. Clearly it doesn’t seem to include the ability to actually read the manufacturer’s label. Or even worse, the certification doesn’t obligate the person to actually follow the instructions on the label.

    Thanks for your visit and for this excellent example of the damage we are inflicting on ourselves and our public lands.

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