Does your dog go bananas every time you drive past a green, grassy park? Most of us enjoy taking our dogs to play on public lawns whenever possible, to enjoy the open space, fresh air, sunshine, and perfect footing for fetching. And dogs enjoy it, too, as evidenced by that excited whining that builds in volume as you approach your favorite park. Unfortunately, those grassy spaces we all enjoy so much may pack a lethally toxic punch for our canine partners. Lush, green lawns are often maintained on a regular program of pesticide applications, with potentially poisonous effects on our pets.
The grass IS greener
Not all lawns are maintained with chemicals, but many of them are. According to a study publicized in an April 1999 Newsweek article, the number of Americans treating their own lawns with chemicals has risen from 55 percent to 67 percent in the last decade. Businesses generally engage professional gardening services to maintain their lawns – and most commercial services do use chemicals. Cities and school districts, too, generally rely heavily on chemical sprays to help them control weeds and pests.
According to the Pesticide Management Education Program (PMEP) at Cornell University, there are some 223 chemicals that have home lawn uses, though the majority are used infrequently. PMEP estimates that 35 active ingredients are used in more than 90 percent of lawn treatments, which have various purposes. There are pre-emergence crabgrass treatments, broad leaf weed controls, insect controls, and fungicide treatments for control of lawn diseases.
We know that these chemicals have the potential to hurt humans and animals – they can cause reproductive and neurological problems, organ damage, endocrine and/or immune system dysfunction, and are potent carcinogens.
According to the Environmental Protection Agency, however, if these chemicals are used according to label instructions – which are regulated and enforced by Federal law – lawn care chemicals pose little risk to people or pets. The number of incidents is low, and primarily involve the misuse of a product “where the product was not applied correctly or those affected did not wait until the application was dry before re-entering.” Children and pets, the EPA acknowledges, have the greatest potential danger if these products are misused.
One of the basic tenets of holistic health care is to reduce exposure to toxins whenever possible. This is much more easily accomplished if you are a human than if you are a dog, however. Undoubtedly, they have more exposure to chemicals than we do.
Long-term effects on pets not known – or studied
But few in the veterinary world seem to have given much thought to the risks of lifelong, low-level exposures. Patricia Talcott, DVM, secretary-treasurer of the American Board of Veterinary Toxicology (and herself a veterinary toxicologist) acknowledged that she was unaware of any studies conducted to determine the risks of long-term, low-level exposure to lawn-care chemicals on dogs. Dr. Talcott did recall seeing one “small-scale, short-term” study that looked at the effects of varying doses of the potent herbicide 2,4-D, a common ingredient in most commercial “weed and feed” lawn treatments. And most reports of adverse effects of these chemicals on pets, she says, have been due to acute cases of accidental poisoning.
“Most of the poisonings we see that involve lawn chemicals are related to 2,4-D,” Dr. Talcott says. “But in most cases, these exposures were due to incorrect applications – someone spilled a lot of the chemical and didn’t clean it up, and a dog walked through it, for example.”
Our research turned up only one statistic concerning the potential effects of long-term, low-level exposure on dogs, quoted by many sources (and repeated here): In 1991, a survey conducted by the National Cancer Institute, found rates of lymphoma to be twice as high in dogs whose owners used preparations that contained 2,4-D on their lawns as in dogs whose owners did not use the chemicals.
It is well-documented, however, that long-term exposure to even low doses of pesticide exposure can cause myriad health problems in people. Pesticide residues can be inhaled or absorbed through the skin, where they can cause central nervous system disturbances and affects organ function. But these effects have been observed largely in populations of people with known exposures to pesticides. For example, a pesticide sprayers have been shown to have significantly higher incidence of lymphoma and possibly other immuno-response deficiencies. And a University of Iowa study of golf course superintendents also found abnormally high rates of death due to cancer.
However, if you were not aware that you had been exposed to pesticides or any other lawn-care chemicals, it would be difficult for a doctor to make a link between any ill effects you had suffered and the chemicals. Poisonings with these substances can cause symptoms that mimic flu, allergy, or other minor ailments, such as headaches, nausea, fever, breathing difficulties, and high blood pressure.
This is also true of animals, says Dr. Talcott. “Herbicide poisonings often mimic other diseases. It can be very difficult for a veterinarian to establish a true-cause-and-effect relationship between the exposure and the illness.” Blood chemistry tests that could make that link are rarely ordered due to their high cost, Talcott added.
Most accidental pesticide poisonings in pets have occurred as a result of exposure to freshly applied or spilled pesticide; theoretically, simply avoiding fresh applications of the chemicals would protect your pet, since pesticides break down or “degrade” over time in sunlight and via microbial and chemical reactions in the soil.
However, degradation time is measured in “half-life,” the amount of time it takes for half the amount of the pesticide in soil to be deactivated. The most common active ingredient in lawn-care pesticides is 2,4-D, is classified as “non-persistent,” but this is defined as “a half-life of less than 30 days.”
Given that we know pesticides are highly toxic to all animals, and that their use is prevalent in public lawn care programs, it is prudent to be vigilant when bringing your dog to public fields for recreation. If you observe spraying in progress, avoid that field for a while. How long? The label directions for every lawn-care chemical suggest that people and pets should be kept off treated lawns until they are dry, which, depending on the weather, could take from an hour to several days. We’d probably give it wide berth for at least a week or two.
It has been estimated that between three and five percent of all people are chemically sensitive to the point of experiencing ill effects from levels of pesticide exposure considered “safe” by the EPA. There is no reason to believe that other mammal species, including dogs, would be much different. If your dog has chronic ill health, and is exposed to lawn chemicals on a regular basis, whether through your own gardening practices, a neighbor’s, or through recreation on public lawns, consider having your veterinarian conduct tests to determine whether pesticides could be the cause.
-By Nancy Kerns