Ah, spring. You can smell it on the air — that bracing ammonia odor wafting off your neighbor’s lawn; the acrid stench at the local home store, where the first six aisles have been packed with heaping bags of the season’s poisons.

The Natural GardenerHydramethylnon, glyphosate, dicambra, atrazine and 2,4-D.

There’s a little something to wipe out every potential lawn and garden interloper, but perhaps the most popular consumer weapons in the annual war on nature are the “weed and feeds.” These fertilizer-herbicide combos were conceived of in the US more than 50 years ago as a way to enrich turf grass, while simultaneously stamping out invading weeds.

With names like Turf Builder and Bonus S, these formulations sound tame, and in part, they are — bags of dirt fortified with nitrogen and assorted minerals to fulfill the “feed” half of their pledge. Only a small, government-allowed dab of herbicides is included to “weed” the turf.

Chemical manufacturers say these “active” ingredients are safe, when used as directed, and note that they biodegrade over time in soil and water. (Though how much time varies greatly depending on conditions as studies of common lawn herbicides show.)

But critics say that with upwards of 30 million pounds of weed-and-feed applied to residential lawns, golf courses and other turf landscapes in the US every year, these chemicals are contributing to a toxic environment. They perform as ordered, at least in the short term, squeezing out crab grass, sledge and dandelions to make way for the cultivated grasses we know and well, cultivate, like Kentucky bluegrass, St. Augustine and the revered and reviled Bermuda. But they annihilate the beneficial earthworms, soil microbes and insects that make for a healthier ecosystem.

Our turf ends up on a monthly treadmill of “treatments.” But that’s the least of it. The worst may be that undissolved herbicides and fertilizers wash off down storm drains, boomeranging back to us in drinking water, and track their way indoors on the feet of our pets and kids.

Environmentalists and scientists are worried that the aggregate effect and universal dissemination of these chemicals year after year may be lapping over the levy of our human defenses, tricking our immune and hormonal systems and triggering diseases.

Here are five vital creatures and resources you may be harming when you weed-and-feed:

1 – Birds

Lawn chemicals hurt birds. Our avian friends are vulnerable because they feed on seeds and weeds on lawns, where they directly ingest freshly distributed weed and feed granules. The Audubon Society estimates that 7 million birds are killed every year by the “aesthetic” use of lawn chemicals.

The weed and feed you’re using most likely relies on either atrazine or 2,4-D, two potent chemicals that date to the 1940s and 1950s, the dawn of chemical agriculture. During this period, public ignorance about herbicides lead to the extensive use of another chemical DDT, blamed for killing millions of birds and livestock and nearly annihilating the American Eagle before being banned in the 1970s.  2,4-D, became notorious later, as a key component of Agent Orange, the defoliant used in the Vietnam War and blamed for a variety of health problems in veterans.

Like DDT,  atrazine and 2,4-D effectively kill weeds. The question that many groups like the Audubon Society, Natural Resources Defense Council and Beyond Pesticides are asking is: Is this function worth the collateral damage? Today, chemicals are used more moderately than during the 1950s when DDT was indiscriminately sprayed on farm land and over homesteads. But critics maintain that the surviving legacy pesticides still pose problems.

For the record, both chemicals have been extensively tested and deemed safe at recommended usages by the US Environmental Protection Agency (EPA). Critics note, however, that many of the studies underpinning EPA approval have been done by the chemical manufacturers, who are required to submit research to obtain EPA registration.

The EPA bases its approval on this research by the companies, as well as the science at large, but the latter is often less extensive because independent researchers are not as well-funded. (In this Los Angeles Times article you can read how a pesticide industry task force ultimately assembled 270 toxicity studies on 2,4-D.)

This “self-serving system” stacks the deck with industry findings that unsurprisingly show their chemicals are safe, says Jay Feldman, executive director of Beyond Pesticides, a group fighting to reduce or eliminate pesticide use in the US.  It also leads to higher than needed pesticide use, because the industry studies help shape the levels of use, he says, citing a recent rollback in the “safe” tolerances for 2,4-D.

In that case, the chemical maker responded to EPA worries that aggregate human exposure to 2,4-D from dietary and other sources was raising the agency’s “level of concern” by  conceding that agricultural applications of 1.5 pounds per acre would be as effective as the recommended, EPA-allowed two pounds per acre.

The case exposed a flaw in the system in which the chemical companies have no incentive to recommend the lowest possible dosages of their products, Feldman said.

2 – Frogs

Lawn chemicals hurt frogs. Atrazine, in particular, is believed to be killing off frog populations by weakening, sickening and reducing their size, thereby impairing their ability to survive. Significant exposure to atrazine also renders frog populations unable to reproduce, literally changing male frogs into females.

A University of California Berkeley professor, Dr. Tyrone Hayes, believes he’s discovered how atrazine devastates amphibians. Atrazine, he says, affects an enzyme in amphibians – and fish, reptiles, birds and many mammals – called aromatase. Aromatase converts androgens to estrogens, demasculating and feminizing the affected animal, says Hayes, who has been studying how frogs are affected by herbicides for more than a decade.

Frogs, susceptible to atrazine, because it ends up in aquatic environments where they absorb the chemical through their skin, may be just the beginning.

Dr. Kerry M Kriger, another amphibian expert and founder of Save the Frogs!, explains why atrazine jeopardizes both frog and human health in a letter to the EPA supporting his call for a ban on atrazine.

“Amphibians have permeable skin that readily absorbs these pollutants. Atrazine has been shown to cause immunosuppression, hermaphroditism and even complete sex reversal in male frogs at concentrations as low as 2.5 parts per billion. As humans and frogs share half their DNA, it is unfathomable to think that Atrazine is harmless to humans or the other species with whom we inhabit this planet.”

One third of frog species world wide face imminent extinction, which will certainly have a ripple effect on their ecosystems. Ironically, frogs play a role as natural pest control, eating insects and in turn serving as prey for larger animals.

The US EPA does not recognize atrazine as the culprit in the decline of frogs, as Hayes and Kriger do. After reviewing lab and field studies and the published literature, the agency has determined that “atrazine does not adversely affect amphibian gonadal development“.

3. Lawn chemicals end up in your drinking water

You’ve heard the environmentalists lament that humans, unlike any other living beings, soil their own nest. Pesticides appear to give full expression to that self-defeating behavior.

Atrazine, for example, has been found in drinking water for decades, sometimes in trace amounts and sometimes exceeding safe thresholds. The contamination mainly comes from its use on crops, but lawn use accounts for 7 percent or more of the atrazine purchased in the US.

A USDA report in 1994 (Atrazine: Environmental Characteristics and Economics of Management) determined that  it “has been found in surface water used for public water supplies in the Midwest at levels greater than the standards established by the Environmental Protection Agency.”

At the time, the USDA concluded that controlling its usage would be more economical than banning atrazine because scientists assumed that farmers had a great need for the herbicide. That assumption has been challenged by organic farmers and subsequent studies have shown that organic farming can produce yields very close, and sometimes better, than those produced by chemical operations. (Here’s a synopsis of a 2005 Cornell study showing organic corn and soybean production held up when compared to crop yields from chemical farms.)

In 2008 and 2009, the USDA again looked at the issue, conducting tests in the most heavily affected, crop-growing Midwest to determine if atrazine was present in drinking water. Its findings:

  • 94% of the 618 samples analyzed of American tap water were contaminated with atrazine, with a maximum concentration of 2.8 parts per billion. According to Dr.Krider, that’s “enough Atrazine to turn a male a frog into a female”.
  • 12.6% of the 238 groundwater samples analyzed were contaminated with atrazine.

Atrazine contamination isn’t just a problem in the US. In 2004 the European Union banned the chemical because tests showed turned up repeatedly in tap water.

The EU applied the precautionary approach, clamping down on the herbicide to avert both known and unknown or potential risks to human health. Their decision came as emerging research showing that synthetic chemicals may interfere with human biology, affecting the endocrine system, even at very low levels of exposure.

4. Your kids

Children may be more profoundly affected by small, chronic pesticide exposures than adults because they are relatively smaller and still growing, according to numerous studies and reports.

Kids also can have a more pronounced reaction to an acute encounter with pesticides, say if they’re accidentally sprayed with pesticides or roll around in treated grass. Case studies show this can cause immediate harm, contributing to asthma, rashes or disorientation.

(Dogs too, exhibit a sensitivity, related to acute and chronic exposure. One study on canines found that cancer rates were twice as high among dogs living at households where lawns were treated four times a year compared with dogs unexposed to lawn chemicals.)

In 2005, the Organic Consumers Association gathered evidence showing that cumulative exposure to residues on foods from pesticides — some of which, like 2,4-D, are the same as those used on lawns — could affect child development. The OCA summed up:

“According to the Environmental Protection Agency (EPA) and the National Academy of Sciences, standard chemicals are up to ten times more toxic to children than to adults, depending on body weight. This is due to the fact that children take in more toxic chemicals relative to body weight than adults and have developing organ systems that are more vulnerable and less able to detoxify toxic chemicals.”

Similarly, Beyond Pesticides notes:

“The National Academy of Sciences reports that children are more susceptible to chemicals than adults and estimates that 50 percent of lifetime pesticide exposure occurs during the first five years of life.

EPA concurs that children take in more pesticides relative to body weight than adults and have developing organ systems that are more vulnerable and less able to detoxify toxic chemicals.”

Findings showing that kids take on a proportionately heavier load of chemicals — from food, plastics, and household products — has led to concerns that lawn chemicals contribute to their “body burden,” in the parlance of those who discuss personal pollution issues.

Scientists are finding that pesticides, like certain components in plastic such as BPA, can disrupt the human hormone system. Both major weed and feed chemicals, atrazine and 2,4-D, are considered to be “potential endocrine disruptors” (along with an array of other pesticides), meaning they can interfere with the human body’s hormonal system.

Endocrine disruptors are known for their insidious way of creeping into the human body undetected at low levels, essentially thwarting the body’s usual defenses. They mimic or interfere with natural hormones, acting on the thyroid or pituitary glands, reproductive organs and the brain.

Studies suggest that this interference can cause problems with child or fetal development, and metabolism and fertility, later in life.

The effect of synthetic endocrine disruptors on reproductive organs could explain why human fertility issues are suddenly “off the Richter scale,” said Mark Kastel of the Cornucopia Institute in a recent interview.

“Sometimes exposures to these toxics can have catastrophic lifelong impact,” he said. “It might be a triggering device, especially in the reproductive organs, causing them to develop inadequately.”

Endocrine disruption is just one way pesticides may harm kids.

Two studies by Minnesota researchers found that pesticides, either a mix that included 2,4-D but also fungicides and glyphosate, appeared to raise the risk of birth defects among the children of exposed farm families.

Other studies have found that the use of household and lawn pesticides raises the risk of childhood leukemia (here’s one paper that reviewed 17 studies of the link to leukemia). Beyond Pesticides has collected a long list of research, showing  implicating pesticides in childhood development issues, increased asthma rates and even brain cancer.

5. Yourself

Exposure to pesticides could increase your risk of getting cancer.

Pesticides have long been suspected of increasing the risk of certain cancers, though drawing a direct link has proven difficult because adults are simultaneously exposed to other carcinogens, such as radiation, cigarette smoke and food additives.

Several studies (here’s just one set related to 2,4-D, however, have indicated a link. Here are a couple of the more compelling findings:

The EPA holds that 2,4-D cannot be “definitively linked” to human cancer cases. But studies showing it harms the gonads and thyroid gland in lab animals has convinced the agency that “there is concern regarding its endocrine disruption potential.”

As for atrazine, EPA also has so far concluded that cancer worries are unfounded. In 2000, after surveying the “best available scientific data” and inviting public comment, the agency determined that “atrazine is not likely to cause cancer in humans.”

In 2011, it went further, declaring that recent analysis done as part of the Agricultural Health Study (AHS) and   an updated epidemiological study of people exposed to atrazine “ have shown no relationship between atrazine and prostate cancer or non-Hodgkin’s lymphoma.”

However, the EPA is reviewing the safety of atrazine. In 2011, an independent, EPA-appointed panel determined that there is reason to believe atrazine has “carcinogenic potential” in ovarian cancer, non-Hodgkin’s lymphoma, hairy-cell leukemia and thyroid cancer. It found insufficient evidence for links to other types of cancer.


Check out your weed and feed at the Household Products Database.

The NRDC produced a report on atrazine contamination of drinking water called Poisoning the Well.