Lawn Chemicals Linked To Two Types Of Canine Cancer

The obsession with well-manicured lawn could be killing your dog (and you)…

Chances are toxic pesticides are used to maintain that perfect green. Did you know that lawn chemicals may cause malignant lymphoma and bladder cancer in your dog?

lawn chemical canine cancer, roundup, weed killer, pesticide, herbicide
(Photo by: Global Justice Now)

Canine Malignant Lymphoma (CML)

A study1 by Cummings School of Veterinary Medicine at Tufts University found that exposure to specific lawn care chemicals was linked to a greater risk of canine malignant lymphoma (CML). In particular, the use of professionally applied pesticides was associated with a significant 70% higher risk of CML. The use of owner applied insect growth regulators also significantly increased CML risk.

An earlier study2 also found a positive association of CML with dog owner’s use of 2, 4-Dichlorophenoxyacetic Acid (2, 4-D) herbicides. The risk of CML doubled when owners applied 2, 4-D to their lawn, four or more times per year.

2, 4-D is a type of phenoxic herbicide, commonly used in agriculture, forestry, on pastureland,  rights-of-way, lawns and golf courses.

The frequent use of phenoxy herbicides, especially 2,4-D, has been linked with 2- to 8-fold increases of human non-Hodgkin’s Lymphoma (NHL) in studies carried out in several countries.

Canine Bladder Cancer

In a study3 conducted by Purdue University on Scottish Terriers, researchers detected lawn chemicals in dogs’ urine following home lawn chemical application. Dogs exposed to phenoxy herbicides were at a significantly increased risk of bladder cancer.

Scottish Terriers are genetically predisposed to developing bladder cancer – being 18-20 times greater than that of mixed breed dogs. Exposure to lawn chemicals has been found to increase the risk of bladder cancer in Scottish Terriers by 4-7 times.

scottish terrier canine malignant lymphoma

For this study, researchers measured the 3 common chemicals used in lawn care products:

  • 2,4-dichlorophenoxyacetic acid (2,4-D)
  • 4-chloro-2methylphenoxypropionic acid (MCPP)
  • dimethyl 2-(difluoromethyl)-4-(2-methylpropyl)-6-(trifluoromethyl) pyridine-3,5-dicarbothioate (dithiopyr)

Following treatment of lawn with herbicides, there was widespread detection of 1 of the 3 common chemicals in the urine of dogs in 19 of the 25 treated households. As chemical carcinogens were internalised by dogs and excreted in urine, this could expose the urothelium (which lines the inner surface of the urinary bladder) to harmful chemicals.

Owners of Scottish Terriers are advised to restrict their dogs’ access to chemically treated lawns until further studies are carried out.

The results of canine studies raise concern for potential human exposure from lawn chemicals…

Canine cancers are well establised models for human cancers. Both canine lymphoma and bladder cancer closely resemble human non-Hodgkin’s Lymphoma (NHL) and bladder cancer in clinical, pathologic and histologic features, and treatment response.

Human Non-Hodgkin’s Lymphoma (NHL)

The incidence and mortality of NHL have risen dramatically since the 1970s, yet the causes of this increase are not known. This could be in part due to the significant increase in pesticide use, particularly phenoxy herbicides. Many studies have looked into the potential link between agricultural chemical exposure and NHL but with inconsistent results.

It can be difficult to evaluate the impact of environmental risk factors, including exposure to pesticides, on human health. The role of pesticides in the aetiology of cancer is controversial. As dogs and their owners share the same household, they have similar environmental exposures. The results from canine studies could provide insight into how pesticide exposure may contribute to human NHL (and other cancer).

Human Bladder Cancer

About half of human bladder cancer cases are thought to be due to exposure to cigarette smoke and chemicals in the workplace. Genetic factors, especially in relation to chemical exposures, are associated with an increased risk of the disease. However, more than half of the patients have no known risk factors.

Since certain breeds of dogs such as Scottish Terriers are more likely to develop bladder cancer, they provide the opportunity to study heritable factors and gene-environment interactions that increase human bladder cancer risk. Humans and dogs often share genes that can predispose them to cancer. Once heritable factors of dogs are determined, they can be studied in humans. Finding the dog gene may help to identify the corresponding human gene for bladder cancer. This means discovering genetically predisposed individuals who should stay away from lawn chemicals.

Bottom Line…

Studies have linked long term pesticide exposure in farm workers to increased risk of Alzheimer’s and Parkinson’s disease, prostate, ovarian and other cancers, depression and respiratory problems. Since pesticides are endocrine disruptors, they may cause fertility issues, birth defects, immune system damage and neurological disorders. Children are most at risk as their organs and nervous systems are still developing.

RELATED: How To Protect Against Toxic Weed Killer Glyphosate

We are already exposed to pesticides through food, water and air on a daily basis. Personally, I won’t wait for more studies to determine the health effects of pesticides. Protect yourself, your family and pets by taking the necessary precautions to reduce pesticide exposure as much as possible – that includes not using lawn chemicals.

1.Household Chemical Exposures and the Risk of Canine Malignant Lymphoma, a Model for Human Non-Hodgkin’s Lymphoma.

2. Case-Control Study of Canine Malignant Lymphoma: Positive Association With Dog Owner’s Use of 2, 4-Dichlorophenoxyacetic Acid Herbicides.

3.Detection of Herbicides in the Urine of Pet Dogs Following Home Lawn Chemical Application.

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