MSU Extension PFAS Contamination in Agriculture

PFAS In Home Gardens

There are many benefits to growing your own food in home gardens. However, it is important to take steps to ensure your garden does not contain contaminants that could end up in your produce and those who consume it. There is a risk that PFAS chemicals could enter your garden in a variety of different ways. PFAS chemicals can enter garden produce when plants are grown in contaminated soil or are irrigated with contaminated water. PFAS can also be introduced to the soil by using contaminated fertilizers, pesticides, soil amendments, compost or biosolids in the garden. If you are located near a source of airborne PFAS contamination such as a chemical manufacturing plant, there is a chance PFAS could settle onto your property and contaminate your soil or produce, however not much is known about this route of contamination. 

 If your home is located near a site where environmental contamination has occurred, the ground water in nearby wells may also become contaminated. Click here to view MPART's identified PFAS sites and areas of interest. When contaminated water is applied to gardens, contaminants can be transferred through the soil and ultimately taken up by the plants. These compounds can then bioaccumulate in the crops.

As of 2020, Michigan has regulated public drinking water supplies for seven different PFAS compounds, but private wells are not regulated; however, homeowners using private wells to water their gardens near contaminated sites are advised to test their water for PFAS to prevent contamination. For guidance on testing your residential water for PFAS, click here. 

At this time, we still need more research so that we will be able to predict how much PFAS will end up in plants grown in contaminated soil or irrigated with contaminated water. We do know that plant uptake depends on the concentration of PFAS in the soil and water, the type of plant being grown, the type of soil used to grow the plant, whether they are grown in pots or fields, and the other nutrients present in the soil. The human contamination risk will depend on the portion of the plant that is used for consumption. The risk from occasional consumption of produce grown in contaminated gardens is thought to be low considering people typically consume a variety of different foods, however it is recommended to limit exposure to PFAS compounds whenever possible due to their ability to bioaccumulate and can lead to serious health concerns.

PFAS Testing for Gardeners

If you are interested in testing your garden for PFAS, we recommend starting with water and soil samples. Some laboratories are able to test plant products for PFAS, however because of the variation in plant uptake and how PFAS partitions within the plant, we recommend starting by testing the water and soil. For water samples, there are multiple methods available that test for between 18-40 different PFAS compounds (EPA 537.1, EPA 533, EPA Method 1633 and ASTM D7979). For soil samples, we recommend using EPA Method 1633, this method tests for 40 PFAS analytes. Water and soil samples typically range from $350 to over $600 depending on the laboratory, expected turn around time and if you need assistance with collecting samples. Michigan State University has its own PFAS Analytical Laboratory that is available to analyze a variety of samples including drinking water, surface water, soils, biota, biofluids, groundwater, wastewater, foods and other solids. Other certified laboratories can be found here. MSU staff may be available to help collect samples for an additional cost. Reach out to Faith Cullens-Nobis (cullensf@msu.edu) or Katie King (kingka22@msu.edu) for more information about PFAS testing at MSU.

For soil sampling, we recommend using the Incremental Sampling Method. This method takes a subsample from multiple increments within a decision unit or specific area of interest. This method aims to reduce the variability in data by providing a mean concentration of the PFAS within a given area. For example, in the garden in the figure below, side A has used contaminated compost and side B has not. In this case, two separate soil samples could be collected, one for side A and one for side B. For each sample, multiple increments marked by X’s, are combined into PFAS-free Ziploc bags, and then subsampled to represent the average PFAS concentration per side. Sampling equipment should be decontaminated between sites/ samples, but does not need to be decontaminated between increments. Ideally, between 30-100 increments would collected per sample, and each site would be sampled in triplicate to ensure the accuracy of the PFAS concentrations found in each sample. Please reach out to MSU for further assistance with soil sample planning.

When sampling it is important to avoid cross contamination. PFAS are present in many consumer products so it is important to avoid these when collecting samples to test for PFAS. For example, PFAS can be found in cosmetics, deodorants, moisturizers, makeup, sunscreen, waterproof or water resistant clothing, Gore-Tex materials and more. For a full list of materials that can and cannot be used when PFAS sampling, refer to the guidelines for soil, residential well and surface water sampling. MPART has also created videos that walk homeowners through how to collect samples for PFAS water analysis, along with other helpful information to ensure success when sampling. 

PFAS reports from testing laboratories can be difficult to understand. Generally, PFAS levels in water samples will be reported in parts-per-trillion (ppt) or nanograms per liter. Soil and other solid samples are typically reported at the part-per-billion (ppb) or microgram per kilogram level. For more information about what your results mean, we have put together a resource that walks you through these reports. If you would like to discuss your results with someone on our team, please reach out to Faith Cullens-Nobis (cullensf@msu.edu) or Katie King (kingka22@msu.edu). If you would like your results to remain confidential, do not include any sensitive information about your results in your email, and we can schedule a time to talk over the phone.

Strategies for Reducing PFAS Contamination in Gardens

Although research is limited at this time in terms of how to eliminate PFAS from gardens, there are some actionable steps you can take to reduce PFAS contamination in your garden.

• If your irrigation water contains PFAS, you can either install a granular activated carbon or reverse osmosis filter to remove the PFAS. For more information about filters, visit the Michigan Department of Health and Human Services or Environmental Protection Agency webpages.
  • • Another option is to collect rainwater to use for irrigation.
• If your soil is contaminated, raised beds filled with clean soil can be a helpful alternative to ensure PFAS is not taken up by plants. With this method, it is important that the roots of plants do not extend past the clean soil in the raised beds.
• Add clean organic matter to the soil. Some examples of this would be uncontaminated peat, manure or compost. Studies have shown that increased levels of soil organic matter helps to reduce PFAS accumulation in plants.
• Wash all of your produce with clean water and make sure to scrub and peel root vegetables before eating them.
• Avoid using contaminated materials in your garden beds, such as:
  • • Contaminated fish waste as a source of nitrogen. Several fish species in contaminated waterbodies accumulate high levels of PFAS and when their scraps are used as soil amendments, PFAS can enter the garden and be taken up into your plants.
    • Biosolids that are untested.
    • Compost from industrial food waste that may inadvertently contain plastics or PFAS from compostable foodware. 
• Check specific fertilizer and pesticide brands to see if they have done any PFAS testing of their products.
• If you raise animals like chickens, make sure you provide them with clean feed and water to prevent PFAS accumulation in their meat and eggs.
• Avoid using materials in your garden that may contain PFAS like, wood, carpet, cardboard, tires, etc.
  • • Cardboard is a very popular soil amendment for weed control. If you chose to use cardboard in the garden, use non-glossy, brown cardboard without tape, staples, etc. While using plain, brown, corrugated cardboard is low risk, cardboard manufacturing often includes recycled materials, and may include PFAS unintentionally through the recycling streams.
• Although research is limited, some initial studies have shown that PFAS tend to accumulate more in the leaves of plants than the edible fruit portion. Additionally, studies have found that root vegetables and grains (wheat and maize) had lower PFAS concentrations compared to legumes and leafy vegetables. This research can be used to inform planting choices in your garden and will be updated as new studies are published.
  

  • • Per- and polyfluoroalkyl substances (PFAS) in homegrown crops: Accumulation and human risk assessment

      • • • • Private gardens located at various distances from a fluorochemical plant in Belgium monitored the accumulation of 29 PFAS in a variety of crops (both annual and perennial).
            • Soil concentrations of total PFAS did not show significant differences across depth layers (0-5 cm, 5-25 cm, 25-45 cm).
            • Total PFAS concentrations were highest in legumes, followed by fruit vegetables, leaf vegetables, herbs, walnuts, large fruit, root vegetables, small fruit, and shoot vegetables (from highest to lowest).
            • Perennial crops showed a larger number of compounds (18-21) compared to annual crops (9-19).
            • Total PFAS concentrations were higher in annual crops (fruit vegetables, legumes and leaf vegetables) compared to perennial crops, root vegetables and shoot vegetables.

    • Multiple crop bioaccumulation and human exposure of perfluoroalkyl substances around a mega fluorochemical industrial park, China: Implication for planting optimization and food safety

      • • • • Two fields growing vegetables and grains were used in this study. One was 0.3 km away from the mega-fluorochemical industrial park (FIP) and the other was 10 km away.
            • These plots were irrigated with local groundwater and the frequencies were based on normal agricultural practices for specific crops.
            • Soil concentrations in the 0.3km field were between 79.9 ppb- 200 ppb. In the 10 km field, they ranged between 2.09 ppb-3.75 ppb.
            • In the 0.3km field, the concentrations in the edible part of the crops were the highest in lettuce leaf and radish shoot (approx. 4,000 ppb) followed by carrot shoot, Chinese cabbage leaf, Chinese chive leaf, pepper fruit, soybean grain and celery shoot. The lowest concentrations (under 1000 ppb) were found in maize grain (lowest), radish root, carrot root, Welsh onion shoot, cauliflower, wheat grain and pumpkin fruit.
            • The 10 km field showed the highest concentrations in carrot shoot, followed by radish shoot, Chinese chive leaf, Chinese cabbage leaf, lettuce leaf and pepper fruit. The lowest levels (under 10 ppb) were found in maize grain (lowest), wheat grain, carrot root, cauliflower, radish root and Welsh onion shoot.
            • From both fields, the highest levels were found in the radish and carrot shoots along with the cabbage, chives and lettuce leaves while the lowest concentrations were found in the grains, roots and fruits.
            • Across multiple crops, there was an inverse relationship between the carbon chain length in PFAS and the bioaccumulation factors (short chain PFAS tended to bioaccumulate more than longer chain PFAS).
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