FAQ: PFAS in Surface Waters Sources and Fish

How does PFAS get into Ponds, Lakes, and Streams?

PFAS (Per- and polyfluoroalkyl substances) commonly occur in the water and sediments of ponds, lakes, and streams because of their connections to current or past PFAS pollution sources on the landscape. Because the occurrence of PFAS in water bodies is related to their proximity to contamination sources, some water bodies might have relatively high concentrations, whereas others may have no detectable amount. As shown in Figure 1, PFAS can enter surface water and groundwater sources through direct discharges from industries that manufacture or use PFAS or treated wastewater effluent. Other pathways can also include surface runoff from agricultural fields where PFAS-contaminated biosolids are applied or areas where PFAS-containing products have been used or disposed of, such as airports, military bases, landfills, etc. Groundwater naturally flows into lakes and streams through a process known as baseflow, which helps maintain water levels during dry periods. Similarly, groundwater may be the main water source for ponds through springs or subsurface flow. This groundwater-surface water interaction can be a hidden PFAS pathway to surface water sources, especially if a local aquifer is impacted by potential PFAS sources.

Although many different PFAS can occur in ponds, lakes, and streams, two of the most studied compounds in aquatic environments and fish are perfluorooctanoic acid (PFOA) and perfluorooctane sulfonate (PFOS). In a study of PFAS across 161 streams in Pennsylvania PFOA and PFOS were among the most frequently detected (Breitmeyer et al., 2023). As shown in Figure 1, some sites did not have any detections while others did. PFOA and PFOS are commonly detected because they were widely produced and used in industrial and consumer products. Although PFOA and PFOS have been phased out in the US, they are still present in the environment because they do not break down easily. PFOA and PFOS are of concern because of their ability to accumulate in fish tissue to higher concentrations than those found in the water and therefore represent a human health concern through dietary exposure (see Why are PFAS a Problem in Fish?).

Why are PFAS a Problem in Fish?

PFAS have been detected in many different fish in Pennsylvania like crappie and bluegill, but are likely to be found in higher concentrations in larger, predatory fish like catfish, bass, and pike. When there are PFAS in ponds, lakes, or streams, individual fish can assimilate the chemicals through contact with sediments and water, which can lead to an increase in PFAS concentration over time. Eventually, the levels in the fish may exceed the concentrations in the sediments or water (a process known as bioaccumulation). Fish can also be exposed to PFAS through their diet. For some PFAS, their concentrations progressively increase in organisms as you move up a food web from smaller prey fishes to large predatory fishes, resulting in predatory fishes having higher PFAS concentrations than the concentrations in the food they eat (a process known as biomagnification). Because PFAS are widely distributed in aquatic systems and have the potential to concentrate in fish, they raise concerns for food safety and human consumption. In fact, dietary exposure from the consumption of freshwater and marine fish and shellfish is predicted to be a primary source of PFAS for many people.

What Regulations Exist for PFAS and Fish?

While the U.S. Environmental Protection Agency (EPA) has established federal standards for six PFAS chemicals in treated drinking water, there are currently no federal guidelines for PFAS in surface waters, caught fish, and other food products. As scientific research and environmental monitoring expand across the country, states are developing and issuing different fish consumption advisories for PFAS, although most state advisories focus on the frequently detected PFOS and PFOA.

Fish consumption advisories are guidelines or recommendations that indicate how often it is safe to consume certain fish species harvested in a specific area. These advisories are issued by states when PFAS are detected above certain safety thresholds or levels. Different states have different PFAS levels in fish that they use to decide when to issue a fish consumption advisory. Fish consumption advisories are recommendations, not laws, so they aren't legally enforced. Instead, these risk-based recommendations use current PFAS monitoring results to determine how often it is safe to consume certain fish species from local water bodies.

The advisories may recommend no consumption ("do not eat") or provide safe meal consumption frequency limits over a specific time period, e.g., servings per week, month, or year, for the general public and sensitive members of the population, like children and pregnant women.  As the concentrations of PFAS in fish increase, the risk to human health increases, and the recommended amount of fish to eat decreases.

Fish are a source of high-quality protein, vitamins, and minerals, and consuming fish has been associated with health benefits. Apart from a "do not eat" advisory, the health benefits of eating fish can still be attained by following the recommended safe meal consumption frequency limits, choosing a different fish species to eat, or fishing from less contaminated waters.  However, because fish in private water bodies are not generally evaluated for PFAS by state agencies, it may be important to test fish in private ponds, lakes, and streams if fish are caught for consumption. This may be especially important if nearby water supplies have tested high for PFAS or if the water body is in close proximity to known PFAS contamination.

Is Swimming Safe if PFAS are Detected in My Pond, Lake, or Stream?

Exposure to PFAS during recreational activities such as boating, kayaking, or swimming in surface water sources where PFAS have been detected are expected to be lower in comparison to consuming contaminated drinking water or food. This is because skin absorption of PFAS is limited; however, care should be taken to limit accidental swallowing of water.

Is Animal Watering Safe if PFAS are Detected in My Pond, Lake, or Stream?

Although there are no safety thresholds for animal drinking water, research indicates that PFAS can accumulate in livestock and livestock products when they use contaminated watering and feed sources. If elevated levels of PFAS are detected in your pond, it is recommended to limit its use as a drinking water source for livestock.

What Can be Done?

If you harvest fish from local waters, check to see if there are fish consumption advisories for your area. How to obtain current listing of fish consumption advisories:

• Call the Pennsylvania Department of Environmental Protection (PA DEP) at 717-787-9637 or visit their website.
• Call Fish and Boat Commission at 814-359-5147 or visit their website.

 If there is a confirmed PFAS contamination issue on the farm or surrounding areas, consider water testing on private farm ponds, lakes, or streams used for fishing or animal watering. Refer to the PFAS Testing Services and Laboratories Directory fact sheet for a full list of laboratories with PFAS testing capabilities.

References

Breitmeyer, S.E., Williams, A.M., Duris, J.W., Eicholtz, L.W., Shull, D.R., Wertz, T.A. and Woodward, E.E., 2023. Per-and polyfluorinated alkyl substances (PFAS) in Pennsylvania surface waters: A statewide assessment, associated sources, and land-use relations. Science of the Total Environment, 888, p.164161. Doi.org/10.1016/j.scitotenv.2023.164161