Pesticides are linked to many health problems. The most serious effects include cancers, neurological disorders, and birth defects. But they can also cause a big increase in asthma attacks and skin diseases. A group of harmful substances called endocrine disruptors are connected to many health issues, including cancer, miscarriage, and problems with the immune system. Pesticides are now often thought to be part of this group.
Impact of pesticides on cats and dogs
Cats and dogs are more prone to many diseases than humans because they have a larger skin area relative to their body size, allowing them to absorb more harmful substances. Additionally, they often lick their fur and paws and don’t wear shoes, which can increase their exposure to toxins.
The smallest kids are the ones who face the greatest risk. Their skin is not as thick and can soak up more than animals’ skin, and it’s also bigger compared to their body size or weight than the skin of adults. Kids’ bodies aren’t as good at fighting off toxins because their immune systems aren’t fully grown yet. They also play in ways that make them more exposed to their surroundings, like rolling on the grass, crawling on it, walking without shoes on it, and sometimes even eating it. So, they take in more of what’s on the grass and do so in more ways than adults. Also, because kids eat and drink more compared to their weight than adults, they take in a larger portion of pesticides that are found on or in food and water.
Non-Hodgkin’s lymphoma (NLH)
When you look up pesticides, you’ll often find reports about a worrying increase in non-Hodgkin’s lymphoma (NLH), a kind of cancer that targets the lymphatic system. This disease, once considered rare, is now the sixth most common cancer in the US. Over a 24-year period from 1973 to 1997, the total number of NLH cases rose by around 80%, or about 3% each year. The NLH rate is also growing in Canada, but at a slower yet noticeable pace of 1 to 1.5% per year.
We are starting to see a strong connection between outside factors, especially pesticides, even though scientists and healthcare professionals are still working to fully grasp this increase. A respected institution, the National Cancer Institute in Bethesda, Maryland, has identified eight possible reasons for non-Hodgkin’s lymphoma in one of their studies. There are four other reasons that could be seen as medical factors, which include genetics, viruses, and existing health conditions. Another four reasons relate to environmental factors, like pesticides. Many studies have pointed to pesticides as either the main environmental risk or a possible cause.
The Potential Harm of Pesticides
Pesticides are known to be harmful because they were originally created as nerve poisons and share many chemical similarities with the gases used in Nazi gas chambers. However, it’s generally believed that there’s a “safe dose” beyond which these substances won’t affect humans. This idea suggests that if a small amount of a chemical appears harmless, then ten or a thousand times smaller doses of the same chemical should also be harmless. This makes sense; for example, while large amounts of oxalic acid in rhubarb pie could be deadly, eating a slice every day wouldn’t harm you. (Luckily, most of it is found in the leaves.)
Some substances and methods don’t have to follow certain rules. Many people know that X-rays are safe, but it’s good to not have them too often. Selenium, a heavy metal, is another example. It’s okay to take a small pill of selenium because our body only needs a very small amount of it. But the EPA’s factsheet on Selenium says that being exposed to selenium for a long time, even in small amounts, can cause loss of hair and fingernails, and harm to the kidneys, liver, brain, and heart.
Exposures
In pesticide testing, more focus is given to acute (single, high dosage exposure) than chronic (long-term, low-level exposure), which is harder to assess. However, recent studies have shown increased rates of cancer and other issues among people exposed to small amounts of pesticides, including farm and factory workers. For instance, a study included in a City of Toronto investigation found that children who grew up on farms or near livestock breeding facilities before the age of 13 and later became farmers or animal breeders themselves had a higher risk of developing various lymphatic cancers, such as non-Hodgkin’s lymphoma.
Pesticides can be harmful not only when used as intended, but also when they transform into different, sometimes more harmful substances. Many chemicals produce gases known as volatile organic compounds (VOCs) when they evaporate. The EPA states that VOCs can cause irritation to the nose, mouth, and eyes, and can damage the kidneys, liver, and brain. Some VOCs are known to cause cancer in animals, while others are suspected or confirmed to cause cancer in humans.
Effects of garden chemicals
When garden chemicals evaporate, they can mix with each other and form new, sometimes unexpected substances. The latest studies on pesticides used on golf courses did not consider the loss of byproducts from breakdown. These products may have different chemical properties and toxicities compared to the original chemicals.
Harmful chemicals can enter our bodies and those of other animals through our mouths, noses, or skin. We can breathe them in, touch them, or eat them. Most studies can only look at one way these chemicals enter our bodies at a time because they need to keep everything else the same to make sure their findings are accurate. According to the studies mentioned, breathing in 15 different substances was found to have “minimal” risks for golfers. However, the study pointed out that this only looked at risks from breathing in these substances. A full risk assessment would also need to consider risks from skin contact and ingestion.
Assessing Pesticides and Chemicals: An Overview
Tests usually study individual, distinct compounds rather than how they might interact when mixed together in a single product or when they are vaporized. This approach is necessary for scientists to understand the specific roles and effects of each chemical, allowing them to attribute their results to a single substance. However, a downside of this method is that many commercial products that you can buy in a store have not been tested as a possum deterrent, except maybe by the company that produces them.
The “inactive” ingredients in most products are not mentioned on the label, even though they can also be harmful or become dangerous when combined with other compounds in the product, particularly when these substances degrade.
The term “inert” here doesn’t mean chemically inactive. It refers to “carrier agents”—chemicals that keep a mixture stable or ensure a solution adheres to the surface it’s sprayed on. While these carrier agents are called ‘inerts’ in pesticides because they don’t harm the targeted pest, according to the EPA, some ‘inerts’ can still cause harmful health effects. Another meaning of “inert” is “not harmful to the targeted pest.” However, it could still harm you.
Of course, not all pesticides fall under the previously mentioned concerns. However, much of what is summarized here applies to many pesticides. All commonly used pesticides are harmful on their own, often mixed with other substances whose reactions are unknown, and they can degrade into additional toxins. They can also evaporate to produce VOCs, which can:
- They are toxic
- They can combine to form new, toxic chemicals
- They contribute to ground-level ozone, which is a serious health risk.
The EPA clearly states that “Pesticides are inherently toxic,” using a definition of pesticides that excludes herbicides but includes substances used to kill rodents, fungi, insects, and bacteria.
