Acknowledgments and Methodology

Acknowledgments

Thanks go to Galbraith Laboratories, Inc. for conducting the total fluorine testing on our samples, and to Dr. Laurel Schaider of Silent Spring Institute and Dr. Gillian Miller of the Ecology Center for reviewing this material. Thanks also to Beth Kemler and Mike Schade of Safer Chemicals, Healthy Families and the Mind the Store campaign for their assistance in collecting samples and review of this article, and Laurie Valeriano of Toxic-Free Future for her review of this article.

Methodology

Because PFAS are such a large and complex class, total fluorine is typically used as a screening method for PFAS treatment. In the case of food packaging, it is the method used by compostability certifiers to exclude PFAS. In this study, we sampled food packaging for testing from 16 locations of the top three burger and three top health-conscious restaurant chains based on whether the packaging held standard or popular menu items that likely used grease- or oil-resistant packaging. We also collected some of the same wrappers or bowls from different locations of the same chain to test for regional variation in key items (these samples are not counted separately in the results presented in Table 1 above, which only shows the number of unique items). Samples were collected in January 2020 at chains in and around New York City, Washington, DC, and Seattle, WA. We commissioned total fluorine analysis of 38 total samples of food contact materials at Galbraith Laboratories (Knoxville, TN) using combustion with ion-selective electrode to determine whether the fluorine levels suggested likely PFAS treatment.

Food packaging products were screened for total fluorine content as an indicator of PFAS treatment, as in previous research.¹ We selected specific products to test after researching the offerings from each restaurant chain. After the items were collected and processed by Toxic-Free Future and Mind the Store campaign staff, we sent them to Galbraith Laboratories, Inc. for total fluorine testing.

Product Selection

Food packaging samples were collected from six fast-food and fast-casual chains in the United States, including three burger chains (Burger King, McDonald’s, and Wendy’s) and three health-conscious chains (Cava, Freshii, and Sweetgreen). We assessed the offerings at these chains and then selected food contact materials from each restaurant for both standard menu items as well as items that are popular or iconic. Among those materials, we selected packaging that may have grease- or oil-resistant properties based on its use. Some of the materials we chose for testing were similar to types of packaging tested in 2017 by Silent Spring Institute et al. in which total fluorine measurements indicated the presence of PFAS.² Availability of items varied among restaurant chains, and between two and nine unique items were selected for each chain.

Sample Collection and Processing

We collected 38 total samples from 16 locations of 6 fast-food and fast-casual chains in 3 states and Washington, DC. Of these, 29 were unique packaging products, and 9 were replicates of some of the unique products collected from multiple locations. The following items were collected from one or more locations:

• Paper wrappers for burgers and sandwiches (including wraps and pitas)
• Paper bags for fries, other fried foods, or greasy desserts
• Paperboard cartons for fries or other fried foods including pieces of chicken
• Thin cardboard carton for burgers
• Molded fiber bowls for salad or warm bowls, and a molded fiber tray for kids’ meals

Click here to download the full list of the products collected. For each item, in addition to the results (in parts per million (ppm)), we provide the chain type, chain name, state of collection, packaging category, type of food the item holds, packaging description, and whether the sample was a replicate. During collection, items were handled minimally and each item was placed in its own sealable plastic bag for shipment to Galbraith Laboratories for total fluorine analysis. Multiples of one key item from each chain were collected from two to three locations to assess regional variation. We collected three Burger King Whopper wrappers, three McDonald’s double cheeseburger wrappers, three Wendy’s small burger wrappers, two Cava bowls, two Freshii bowls, and two Sweetgreen salad bowls. Three samples were marked for duplicate testing by Galbraith to assess reproducibility, and Galbraith staff prepared these for testing at their laboratory.

Fluorine Analysis

All samples were sent to Galbraith Laboratories to be screened for total fluorine as an indicator of likely PFAS treatment. Galbraith combusted each sample in an oxygen flask with a known amount of buffer solution, used an ion-selective electrode to determine the fluoride content in micrograms per liter, and then converted to micrograms per grams, which is equivalent to parts per million (ppm). We adopted a threshold of 100 ppm of fluorine to evaluate whether or not products had fluorine levels indicative of PFAS treatment. This threshold was chosen to harmonize with thresholds used by compostability certifiers. Values above Galbraith’s detection limit (generally 10 ppm) and below 100 ppm may also indicate the presence of lower levels of PFAS, possibly from contamination or recycled content.

Results of Replicate Analysis

Results from three pairs of duplicate tests agreed within a range of 0 to 4 ppm (average percent difference 0.4%) and the tests resulted in the same classification of the item in each case (i.e. above or below the screening level). Our tests in which the same packaging product was collected from two or more different restaurants showed some variation (the percent differences ranged from 10% to 36% for molded fiber bowls and from 10% to 152% for burger wrappers), but they resulted in the same classification of each product (i.e. above or below the screening level). These results are reported individually in the detailed list of results available here.

1. Schreder, E.; Dickman, J. https://48h57c2l31ua3c3fmq1ne58b-wpengine.netdna-ssl.com/wp-content/uploads/2019/05/Take-Out-Toxics-Full-Report.pdf Schultes, L.; Peaslee, G. F.; Brockman, J. D.; Majumdar, A.; McGuinness, S. R.; Wilkinson, J. T.; Sandblom, O.; Ngwenyama, R. A.; Benskin, J. P. Total Fluorine Measurements in Food Packaging: How Do Current Methods Perform?. Environ. Sci. Technol. Lett. 2019, 6, 73– 78. 2. Schaider, L. A.; Balan, S. A.; Blum, A.; Andrews, D. Q.; Strynar, M. J.; Dickinson, M. E.; Lunderberg, D. M.; Lang, J. R.; Peaslee, G. F., Fluorinated Compounds in U.S. Fast Food Packaging. Environ. Sci. Technol. Lett. 2017.

Jen Dickman is the Senior Program Associate for Safer Chemicals, Healthy Families and the Mind the Store campaign. Erika Schreder is the Science Director of Toxic-Free Future. Nancy Uding is the Program Director of Toxic-Free Future.