Canned clams have been in the news lately because of concerns about PFAS contamination. Some people are worried that eating canned clams will expose them to these harmful chemicals. A recent study looked into this issue and found some shocking results.
The FDA announced they found PFAS in canned clams during their most recent food safety testing program. PFAS concentrations in clams ranged from 4,026 to 22,943 parts per trillion. The FDA determined that these concentrations represent a health concern and people should limit their consumption of canned clams. Every sample they tested had high concentrations of PFAS compounds.
In this article, we will take a look at what PFAS are and why they are a concern. We will also discuss the implications of this study and what it means for canned clam eaters.
What is PFAS
PFAS is an acronym for perfluoroalkyl and polyfluoroalkyl substances. They are a group of man-made chemicals that have been used in many industries since the 1940s. Some of the more well known PFAS include PFOA, PFOS, and GenX.
These chemicals are very stable and do not break down easily in the environment. They bioaccumulate – meaning they build up in the bodies of animals and humans over time. This is why they are known as “forever chemicals”.
They can be found in a variety of consumer products, including non-stick cookware, water-repellent clothing, stain-resistant fabrics, and some food packaging. PFAS are also used in industrial and commercial applications, such as in firefighting foams, metal plating, and water-repellent coatings.
How does PFAS get in my food?
PFAS enter the food supply in multiple ways.
- Plants grown in contaminated soil and water. If plants are grown in soil or water that contains PFAS, the chemicals can accumulate in the plant tissue.
- Livestock given contaminated feed and water. Animals absorb PFAS from the water they drink and the food they eat. These contaminants become concentrated in their flesh over time.
- Food packaging. The FDA allows food to be wrapped and stored in packaging that contains PFAS. These materials can contaminate food they contact.
- Food processing equipment. PFAS can contaminate food during the preparation and packaging process. If equipment has PFAS-containing materials, these compounds can be transferred to the food.
Health concerns and PFAS
There are many health concerns associated with PFAS exposure. These chemicals have been linked to cancer, thyroid problems, reproductive and developmental issues, and immune system dysfunction. The EPA has classified PFOA and PFOS as “likely human carcinogens”.
What Levels of PFAS in Food Are Safe?
The EPA has established safe limits for PFAS in our drinking water – the Maximum Contaminant Levels (MCLs) provide their assessment of how much PFAS is safe in our water. There is no similar standard for safe levels of PFAS in food.
One reason for this is that toxicologists can’t agree on how much PFAS we can safely consume. It is difficult to precisely state how much of a dangerous chemical people can ingest before they become ill.
Various government agencies across the globe have established different levels and guidelines. Below are standards provided by the Maine CDS and the EFSA
Maine CDC standard for PFAS in food
The Maine CDC is concerned about PFAS contamination in fish. They developed a very useful guide to let the public know what levels of PFAS in fish they can safely consume. Their new guide is a tool known as chemical-specific fish tissue action levels (FTALs).
FTALs provide the maximum concentration of PFAS in fish that is safe to consume. PFAS levels below their guidelines should have negligible risk of health effects. Maine’s guide also accounts for the bioaccumulation of PFAS in our bodies (i.e., these chemicals are not broken down or discharged). They provide a “meal advice” recommendation to let you know how often you can eat PFAS-contaminated fish.
The table below presents the safe concentration of PFAS in fish you can eat and how often you can consume it. These values are developed by the Maine CDC.
| PFOS in fish (ng/kg) | Meal advice |
| 3,500 | 1 meal per week |
| 7,500 | 2 meals per month |
| 15,000 | 1 meal per month |
| 30,000 | 6 meals per year |
| 60,000 | 3 meals per year |
| > 60,000 | Do Not Eat |
European Food Safety Authority standard for PFAS in food
The European Food Safety Authority (EFSA) sets a limit for combined exposure to 4 PFAS compounds in food – the EFSA is Europe’s equivalent of our FDA.
The PFAS compounds they regulate are:
- perfluorooctanoic acid (PFOA)
- perfluorooctane sulfonate (PFOS)
- perfluorononanoic acid (PFNA)
- perfluorohexane sulfonic acid (PFHxS)
The EFSA limit for the combined total of these four PFAS compounds is 4.4 ng/kg of body weight per week.
PFAS in Clams
The FDA conducted PFAS testing in a wide range of foods. Tests showed detectable concentrations of PFAS in fish sticks, canned tuna, and protein powder.
The FDA tested each canned clams sample for 16 PFAS chemicals. They found 11 different PFAS compounds in the clams they tested. Every sample was contaminated with PFAS.
FDA food testing methodology
It is challenging to test food for the presence of PFAS. The FDA has developed a novel analytical technique to analyze for PFAs in food to overcome this problem.
The researchers have developed a new test that can analyze 16 PFAS chemicals in food using liquid chromatography–mass spectrometry methods. The FDA’s novel method was verified to be accurate for the following food matrices:
- infant formula
- strawberry gelatin
- pancake syrup
- cream cheese
- shredded wheat cereal
- lettuce
- milk
- bread
- salmon
The FDA food test method quantifies the following PFAS chemicals:
| Acronym | Name |
| PFBA | Perfluorobutanoic acid |
| PFBS | Perfluorobutanesulfonic acid |
| PFPeS | Perfluoropentanesulfonic acid |
| PFPeA | Perfluoropentanoic acid |
| PFHxA | Perfluorohexanoic acid |
| HFPO-DA | GenX |
| PFHxS | Perfluorohexanesulfonic acid |
| NaDONA | Sodium dodecafluoro-3H-4, 8-dioxanonanoate |
| PFHpA | Perfluoroheptanoic acid |
| PFHpS | Perfluoroheptanesulfonic acid |
| 9Cl-PF3ONS | Potassium 9-chlorohexadecafluoro-3-oxanonane-1-sulfonate |
| PFOA | Perfluorooctanoic Acid |
| PFOS | Perfluorooctanesulfonic acid |
| PFNA | Perfluorononanoic acid |
| 11Cl-PF3OUdS | 11-chloroeicosafluoro-3-oxaundecane-1-sulfonic acid |
| PFDA | Perfluorodecanoic acid |
PFAS testing results for clams
The following table presents the sampling results for canned clams analyzed by the FDA in their 2022 FDA food safety survey. These results are for total PFAS detected in canned clams.
| Item Description | Total PFAS |
| Smoked baby clams in soybean oil | 5,878 |
| Smoked baby clams in cottonseed oil | 4,026 |
| Smoked clams in cottonseed oil | 6,409 |
| Smoked baby clams in olive oil | 22,684 |
| Smoked clams in cottonseed oil | 22,943 |
| Smoked baby clams in soybean oil | 5,553 |
| Whole baby clams in water | 7,374 |
| Chopped baby clams in water | 9,133 |
| Whole baby clams in water | 8,584 |
| Baby clams in water | 10,146 |
These results are in nanograms per kilogram (ng/kg), which is the same as ppt. If you ate 1 kilogram of the sample with the highest concentration (Smoked baby clams in olive oil), you would ingest 3,671 nanograms of PFAS.
A kilogram is 2.2 pounds, which is a lot of clams. However, a typical serving size is 160 grams (0.160 kilograms). If you eat 6 servings of clams, you’ve consumed a kilogram.
How much PFAS is in clams?
How much PFAS are you consuming when you have a portion of clams? Let’s take a look at the sample with the highest concentration – the “Smoked baby clams in olive oil” sample.
Here is the data:
- PFAS concentration: 22,943 ng/kg
- Canned clams portion size: 160 grams (0.160 kg)
- PFAS in serving size of clams: 3,671 nanograms
What would 3,671 nanograms of PFAS do to your health?
Without a national standard for PFAS in food, it’s not easy to know. The FDA noted in their report that these levels are “likely a health concern”.
To help you make sense of these numbers, we can compare the FDA’s testing data to the Maine CDC standard and the EFSA limit.
Maine CDC FTAL: The Maine FTAL lists various PFAS concentrations with a corresponding limit on the frequency you can safely eat that amount of contaminated seafood. The highest PFAS concentration in the clam samples was 22,943 ng/kg. Comparing this to the FTAL table, we see that this is just below the lowest threshold of 30,000 ng/kg.
According to the Maine CDC standard, you should limit your intake of canned clams to six meals per year.
EFSA Standard: Using the EFSA standard, we have to determine how much PFAS an “average” person can safely consume. The highest amount of PFAS they established is 4.4 ng/kg of body weight per week. An average person weighs approximately 68 kilograms (150 pounds).
Here is the math: 68 kg x 4.4 ng/kg per week = 299.2 ng per week
One serving of the most contaminated clams has 3,671 nanograms of PFAS. This represents about 12 times the weekly limit allowed by EFSA. Theoretically, you should limit your intake of canned clams to once every 12 weeks. This is 4 times per year.
Although the Maine CDC and EFSA guidance says you can eat canned clams, I would avoid them completely. This is troubling, especially since I really enjoy canned clams.
Which PFAS compounds were found in clams?
The FDA found 12 different PFAS compounds in the 10 samples of canned clams they tested. These compounds are:
- PFHxA: maximum value = 204 ng/kg
- PFHpA: maximum value = 263 ng/kg
- PFOA: maximum value = 20,133 ng/kg
- PFNA: maximum value = 796 ng/kg
- PFDA: maximum value = 211 ng/kg
- PFUdA: maximum value = 260n g/kg
- PFDoA: maximum value = 130 ng/kg
- PFTrDA: maximum value = 173 ng/kg
- PFTeDA: maximum value = 166 ng/kg
- PFBS: maximum value = 68 ng/kg
- PFHxS: maximum value = 605 ng/kg
- PFOS: maximum value = 1,235 ng/kg
All of the canned clam samples were obtained from China and all were packed in cans. Some of the clams were farm raised and some were wild caught.
The FDA did not identify the specific brands of clams they tested. This makes it impossible to know which brands are safe and which ones are not.
FDA statement on food safety
The FDA provided a lot of information but didn’t offer any explanation about how to interpret the results. The report indicates that PFAS was detected in every can of canned clams, but they did not release the brand names of the clams they tested.
The FDA noted that the sample sizes in their study were limited. Based on this limitation, they could not provide an assessment of the overall safety of the US food supply.
All of this has left many people confused and afraid.
The FDA’s main focus was that while low levels of PFAS were found in three types of food, there is currently “no scientific evidence” that the general public should be alarmed or avoid eating any foods due to these trace concentrations of chemicals.
What Can You Do
Now that you know the risks your family faces from canned clams contaminated with PFAS, what can you do to protect them?
The FDA indicated that all of the clams came from China. An easy way to protect yourself is by avoiding clams that come from China.
You can also educate yourself about food safety so you’re aware of where PFAS might be found. A good starting point is to read my article about which products contain PFAS.
Another approach is to educate yourself about how food becomes contaminated. By understanding how and where PFAS can contaminate your food, you can avoid situations where you’re likely to find problems.
The leading causes of food contamination are:
- growing food in contaminated soil
- watering plants with PFAS-contaminated water
- livestock that consume contaminated feed and water
- using PFAS-containing food packaging
- food processing equipment that includes PFAS
You should limit or avoid the following foods whenever possible:
- salmon and tuna
- clams and oysters
- microwave popcorn
- process foods
It’s important to note that foods that are packaged in PFAS containing materials can impart contamination to the food.
You should regularly test your water to be confirm it is not contaminated with PFAS. Read my guide on testing your water for PFAS.
Final Take
The FDA’s findings have raised some concerns about the safety of consuming canned clams. They found PFAS concentrations ranging from 4,026 to 22,943 parts per trillion. Every clam sample they tested was contaminated.
Although the agency couldn’t say for certain whether PFAS levels in canned clams are dangerous, it’s crucial to be mindful of these possible risks.
If you’re wondering whether your favorite canned clam variety includes PFAS, you should check for any additional test data. Furthermore, it is critical to be aware of food-related dangers posed by PFAS contamination.
Get the most up-to-date information on this problem so that you may make informed choices about which fish and seafood you can safely consume.