The PFAS Problem: Forever Chemicals in Your Backyard Bin
I used to be that person who religiously separated food scraps, proudly turning kitchen waste into “black gold” for my garden. But everything changed when I learned about PFAS contamination in compost. PFAS have been detected in compost at concentrations ranging between 1.26–11.84 µg/kg. Composts are therefore a source of PFAS contamination, posing risks to human and ecosystem health. These aren’t just minor traces—we’re talking about toxic “forever chemicals” that don’t break down in nature.
Finished compost made from manure and food serviceware labeled “compostable” generated at a large fair was found to contain 12 or 13 of the 28 PFAS compounds sampled for, in concentrations ranging from 1.1 to 183 μg/kg. Of note, perfluorooctanoic acid, a known carcinogen, was found at concentrations between 47.2 and 55.5 μg/kg. When the EPA discovered a known carcinogen in something we’re supposed to put on our food-growing soil, that was my wake-up call.
Your Compostable Containers Are the Culprit
PFAS enter organics facilities through multiple avenues, but composters handling food waste largely agree the main source of the chemicals in their facilities is packaging. Those trendy “compostable” takeout containers and coffee cups that make us feel environmentally responsible? They’re loaded with PFAS chemicals to make them grease and water-resistant. We found that compost made from manure and compostable serviceware was contaminated with 20–45 times more PFAS chemicals than separated food waste composted with grass clippings and manure. A sample of manure from the source farm was shown to only contain one PFAS (PFOS) at a relatively low concentration (3.7 ppb), whereas the serviceware compost contained 12–13 PFAS ranging from short-chain (C-4) to long-chain (C-14) PFCAs.
The irony is crushing. We think we’re being eco-friendly by choosing compostable packaging, but we’re actually contaminating the very soil we’re trying to nurture. Even when you avoid adding questionable items to your bin, grease-resistant paper and fast food containers, items prohibited by Ann Arbor’s composting program but sometimes placed in bins regardless still end up in municipal compost systems.
The Health Risks Are Real
They have also been linked to cancer, developmental effects, and other severe health issues by organizations including the U.S. EPA. At least two, PFOA and PFOS, have been phased out of production in the United States. But here’s the kicker—A few years ago, the chemical industry phased out a few of these chemicals and replaced them with new PFAS–not solving the problem. These newer PFAS chemicals have similar health concerns and are becoming increasingly widespread. Sure enough, the study found that the newer generation PFAS chemicals were most prevalent in compost.
While the direct health effects of PFAS exposure through compost are not yet fully understood, studies have associated PFAS exposure with adverse health outcomes, including reproductive issues, liver damage, and certain types of cancers. The fact that we don’t fully understand the risks yet doesn’t make me feel better—it makes me more cautious. When scientists are still figuring out how dangerous something is, maybe we shouldn’t be spreading it on our vegetable gardens.
Your Garden Becomes a Chemical Distribution Center
Here’s what really got to me: The prevalence of short-chain PFAS, such as PFBA, and the downward movement of PFAS with moisture through the 2 ft compost profile demonstrate the potential for groundwater leaching and surface water pollution via runoff when PFAS-laden composts are spread in gardens and on agricultural fields. Every time it rains on your beautifully composted garden, you’re potentially sending these chemicals into groundwater and nearby streams.
According to the study authors, the newer generation PFAS chemicals “tend to be more mobile and have preferential uptake in plants, and thus frequently accumulate in the terrestrial food chain.” Your tomatoes might be absorbing these forever chemicals through their roots, concentrating them in the very produce you’re trying to grow safely. It’s like creating a chemical time bomb in your backyard.
The Time Investment Doesn’t Add Up
Let’s talk about the elephant in the room—time. Results from the pilot project showed that the home composter has the best functionality when 30% to 35% of the container is full. The output of the home composter is fresh and should be stored in a container or spread on the ground for at least 1 month to become fully decomposed. So you’re not just composting—you’re managing a complex system that requires constant attention, proper ratios, and additional curing time.
I calculated the hours I spent managing my compost bins: turning, monitoring moisture, troubleshooting odors, screening finished product. For most home composters, efficiency was analysed in terms of reduction of organic waste collected by the municipal services. An efficiency of 77% on average was obtained, corresponding to a composting rate of 126 kg/person·year of biowaste. That’s roughly 2.5 hours of work per pound of finished compost. I could buy organic compost for less than my time was worth.
Municipal Systems Are More Effective
The research focused on a large-scale quasi-experiment in New South Wales (NSW), Australia, where 24 local governments adopted curbside composting services between 2009 and 2015. By comparing councils that adopted these services with those that had not, the study found that households redirected an average of 4.2 kilograms (9.3 pounds) of waste per week from the landfill stream into the composting stream. Municipal composting programs process waste at much larger scales, achieving better temperatures for pathogen reduction.
Without them, individuals would need to manage their own composting, which can be time-consuming and would require space that not all households have. Moreover, municipal composting services lead to increased composting rates and, consequently, a reduction in emissions from landfills. Professional facilities can also better control contamination and monitor for chemical issues—something impossible in backyard systems.
The Pest and Odor Reality Check
Composting can attract unwanted pests and wildlife, which can create public health risks and damage property. Plus, improperly managed compost piles can emit strong odors, which can create problems for nearby residents and businesses. Anyone who’s dealt with fruit flies swarming around their kitchen compost container or raccoons raiding their outdoor bin knows this struggle is real.
If a compost pile smells, something is wrong. A compost pile that smells like rotten eggs or rotting vegetables has gone anaerobic. This means that there is not enough oxygen to support aerobic microbes and the anaerobic ones have taken over. The constant vigilance required to prevent these problems turned my eco-friendly hobby into a source of stress and neighborhood tension.
Climate Benefits Are Overstated
Yes, Composting reduces methane emissions by keeping wasted food out of landfills. Applying compost to the soil reduces the need for chemical fertilizers, avoiding emissions from their manufacture and use. But let’s be honest about scale. In the U.S., food is the single most common material sent to landfills, comprising 24.1 percent of municipal solid waste. My little backyard bin isn’t moving the needle on climate change.
This study projects that—with the current trends—by the end of 2030, the U.S. can increase the compost to waste ratio by 18% from 10%, reducing carbon emissions by 30 million tons a year while saving around 16 billion USD in municipal waste management costs. These benefits come from large-scale programs, not individual efforts. My time and energy might be better spent on systemic changes like supporting municipal composting or reducing consumption altogether.
Quality Control Is Impossible at Home
Don’t add compost to a seed-starting mix unless you are sure that the pile got hot enough to be sterilized (140 to 160 degrees F). Seedlings are very susceptible to bacteria that are harmless to more mature plants. How many home composters actually monitor temperatures consistently? Professional facilities test for pathogens, heavy metals, and now PFAS contamination.
Composts made from a variety of materials have a range of different contamination levels, the report said. Biosolids are thought to have the highest concentration of PFAS, followed by food waste, then yard waste, according to the report. Without lab testing, you have no idea what’s actually in your finished compost. You might be spreading contaminated material on food you’ll eventually eat.
Economic Reality: It’s Not Actually Saving Money
The average cost to landfill municipal solid waste in the United States was around $55 per ton in 2019. With the United States generating more than 267 million tons of municipal waste in 2017 and sending two-thirds of that to landfills and incinerators, we spent billions of dollars on waste management. But that cost is socialized—I’m not personally paying per pound of waste disposal.
Meanwhile, Compost facilities cost less to construct than to operate, which is reflected in the financial results. The equipment, time, troubleshooting, and replacement costs for home composting systems add up quickly. When I factored in my actual time investment and material costs, buying quality compost was often cheaper than making my own.
Better Alternatives Exist
Instead of composting, I now focus on waste reduction first. I buy only what I’ll use, store food properly, and repurpose scraps in cooking. For unavoidable organic waste, I support robust municipal composting programs that can better manage contamination risks and achieve larger environmental benefits.
By providing convenient composting options through the provision of goods, such as curbside collection, governments can facilitate the diversion of organic waste from landfills to composting facilities, thereby reducing methane emissions and promoting sustainable waste practices. This approach achieves better environmental outcomes without the personal risks and time investment of home composting.
The truth is uncomfortable for many environmental enthusiasts: sometimes the greenest choice isn’t the one that makes us feel most virtuous. After learning about PFAS contamination and honestly evaluating the time and resource costs, I concluded that home composting wasn’t the environmental win I thought it was. Maybe it’s time you considered the same.
