How Microplastics Can Affect Your Dogs and Cats

When people think of plastic pollution, they may picture empty soda bottles, grocery bags, and disposable straws. But you may be surprised to learn that the plastic waste you can't see, like micro- and nanoplastics, is just as concerning. 

Microplastics are just what they sound like: tiny, sometimes even microscopic, plastic fragments or filaments that pollute the environment. These particles may be small, but their impact on our earth is not. Microplastics can find their way into our water, food supply, and even our bodies. Unfortunately, our pets aren't exempt from the effects of invasive microplastics either.   

So, where do microplastics come from? And how do they get into our bodies and those of our pets? We'll answer these questions and let you know how microplastics could affect your pets. 

Microplastic pollution results from the overproduction and overconsumption of plastic, especially the disposable kind.

Microplastics can be as large as a pencil eraser or microscopic — dozens of times smaller than a plant cell. They're found all over the earth, in the soil under our feet, the clothes we wear, the water and food we consume, and even the air we breathe! Analysis of rainwater from the remote mountains of southern France revealed a startling amount of nanoplastic fibers and fragments.

There are two categories of microplastics: primary and secondary. Primary microplastics are intended to be small in size. One example is microbeads, which are common in cleansing gels, cosmetics, and some medications.

On the other paw, secondary microplastics come from larger plastics that disintegrate into smaller particles. Examples of secondary microplastics include tiny filaments from polyester clothing, or a small piece of plastic chipping off an old, brittle soda bottle.

A closer look at the research on microplastic pollution

According to a 2022 report from the Organization for Economic Cooperation and Development (OECD), humans produce 460 million metric tons of plastic globally each year. Experts predict this figure will nearly triple to more than 1.2 billion metric tons per year by 2060.

Most of the plastic we produce (more than 85%) ends up in landfills across the globe. Despite efforts to make recycling more accessible, just 5% of plastic waste is recycled in the US. The OECD estimates that plastic waste found in water sources — including rivers, lakes, and oceans — will triple by 2060. Plastic pollution already threatens more than 2,000 marine species, according to the World Wildlife Fund.

Researchers estimate that the average adult human consumes between 94,000 and 113,000 microplastic particles annually between the food and drink they swallow and the air they breathe. However, these estimates may be far greater (90,000 nanoparticles greater, in fact) for those who consume only bottled water, which is one of the biggest culprits for microplastic exposure.

Chemical and microplastic exposure in pets tends to mirror that of humans, but you may be surprised to learn just how high your pet’s levels of microplastics could be. One study that analyzed pet food and pet feces for traces of polyethylene terephthalate (PET) and polycarbonate (PC) found the levels of these plastics were much higher than anticipated — but that's not all.

The data also revealed that the average concentration of PET in fecal samples was far higher compared to the amount of microplastics in food samples. This means that diet plays only a small role in our pets' exposure to microplastics.

Little research is available on the effects of microplastics on domesticated animals. But, if the studies on humans, rodents, and fish are any indication, they probably aren't great for our fur-babies.

Evidence suggests that microplastics in out pets' food could hinder their digestive processes. According to one study, eating microplastics can cause stunted growth, decreased appetite, internal injuries, and fertility problems in fish.   

Contrary to popular belief, the microplastics aren't just in our pets' gastrointestinal systems. Researchers say nanoplastics are likely in their bloodstreams and maybe even their cells. 

Studies show that nanoplastics can be small enough to cross the blood-brain barrier in mice and fish and that the buildup of plastics in brain tissue can cause vital immune cells to die. When scientists replicated these studies using human brain tissue, the brain cells infiltrated with nanoplastics triggered abnormal gene expression, inflammatory responses, and programmed cell death (as was seen in the mice and fish studies).     

We know that when some types of plastic break down, additives like flame retardants and heavy metals can leach toxins. Multiple studies have found abnormal levels of flame retardant chemicals (PBDEs) in blood serum in dogs and cats worldwide.  

BPA, a common but very concerning plastic additive often used in pet food cans, is a known neurotoxin, hormone disruptor, and carcinogen. While some experts argue that small doses won't harm pets, studies have linked this plastic additive to low thyroid function in felines. What's more, researchers have found BPA in pet foods that do not disclose it as an ingredient.

Lastly, microplastics can harbor bacteria (even strains that are resistant to antibiotics) and can pose an infection risk to humans or pets who unwittingly consume contaminated microplastics.

Although it's "impawssible" to avoid microplastics 100% of the time, there are a few things you can do to reduce your pets' exposure.

• Filter your tap water before giving it to your pets. Avoid giving your animals bottled or unfiltered water since plastic bottles break down, and most tap water in the US contains plastic fibers.  

• Vacuum and sweep often to cut down on microscopic plastic particles. These can accumulate in dust and contaminate the food you eat and the air you breathe. 

• Avoid canned food with BPA linings. BPA is one of the most concerning plastic additives still on the market.  

• Don't buy tennis balls or other dog toys that can break down in your pet's mouth. Instead, opt for sustainable dog toys made of cotton, hemp, or bamboo.

• Avoid eating fish. Sadly, fish (both farm-raised and wild-caught) consume a lot microplastics, and the fish's plastic intake can pass on to the humans and pets who eat them. For this reason, experts suggest cutting down your pet's fish intake. Instead of feeding your cat a salmon or tuna-based kibble, switch to a chicken or turkey recipe and use fish as a special treat. 

• Try to only use natural fibers in your home and your pet's bedding. If your dog wears clothes, stick with natural materials like cotton and bamboo to avoid the plastic fiber shedding from synthetic fabrics.

• Choose eco-friendly leashes and collars. At most big-box pet stores, you'll find a range of dog walking accessories made from non-plastic materials like bamboo, hemp, cotton, and metal.  

• Use a metal or bamboo dog bowl for eating and drinking. Not only will this reduce your pet's microplastic consumption, but these bowls are also built to last longer than plastic options.

• Swap the plastic waste baggies for a greener alternative. Instead of contributing thousands of plastic poo bags to the landfill, use zero-waste poop disposal methods, like biodegradable poo bags or composting.

• Avoid using glitter in your household. This includes hidden glitters like those in nail polish, lotion, and body wash.

• Avoid cleaning or body products with microbeads. These include soaps, abrasive cleaners, toothpaste, sunscreen, and skincare products. 

• Know your plastics. If you have to use plastic products, steer clear of plastic labeled #1, #3, or #6 since these contain more dangerous plastic additives like BPA and styrene. 

Research into the long-term effects of microplastics in pets (and even ourselves) is still in its infancy. However, we know that nanoplastics trigger changes and even cell death within the brain, and that larger particles can interfere with digestion in small animals. 

While it's impossible to eliminate microplastics from our pets' lives completely, there are some things you can do to minimize their exposure, like offering filtered rather than tap water, opting for eco-friendly toys, and using only natural fabrics in your home. Our zero-waste guide to living with a dog is a great place to start if you're thinking about making the change to a more sustainable (and healthier) lifestyle. 

Got more questions about your pet's exposure to microplastics? Chat with a veterinary professional today to get the lowdown on microplastic exposure and the risks.