The hysteria continues. The reaction of the regulators in Maine to PFAS in milk is old news (https://www.pressherald.com/2019/05/19/task-force-on-pfas-forever-chemicals-begins-work-this-week/). Despite historic paper sludge as the likely source, biosolids took the blame. Regulators stopped sales and application of biosolids ‘just to be sure’. Sure of what is a good question. Here I am using the term ‘PFAS’ to refer to the range of compounds that contain fluorine linked to carbon. The longest chain compounds of this class, PFOS and PFOA, have actually been phased out. Most recently, the FDA (Food and Drug Administration) released results from a survey of food products purchased across the US (Article 1). Turns out the milk in ME is not alone. They found PFAS in chocolate cake!!!! Among other foods. All, rest assured, at concentrations too low to merit concern: ‘based on the best available current science, the FDA does not have any indication that these substances are a human health concern, in other words a food safety risk in human food, at the levels found in this limited sampling’. So much for having a glass of milk with your chocolate cake.
Of course, the FDA saying that their survey results were no cause for concern does not mean that no one is concerned. Both composters and biosolids program managers are facing an increased level of scrutiny about concentrations of these compounds in their products and the associated potential for human and environmental health impacts. Regulators in many cases are afraid of being too lax and in some cases (like ME) are potentially over reacting. The stated concern of most regulatory agencies as well as the focus has been contamination of ground water as a result of land application of waste-based materials that contain detectable concentrations of this family of compounds.
One of the major issues is that most utilities (aside from that famous one in Decatur, AL) have no idea what the concentrations actually are. Rooney Kim Lazcano, a graduate student with Linda Lee at Purdue, has been working on just that. She and others in the group have been testing concentrations of PFAS and associated compounds in a range of composts and biosolids (Articles 2 and 3). It turns out that most materials tested contain them. In the 2nd article in the library, the group tested composts. Composts produced with municipal solid waste feedstocks had higher concentrations (29-76 ppb) than composts produced from feedstocks that did not include food wastes (2-8 ppb). The culprit here is food packaging. If you scroll back to the August 2018 library, you’ll find an article on concentrations of these compounds in different types of food packaging. Over half of the dessert and bread wrappers tested positive, with about 40% of the sandwich and burger wrappers also testing positive. Paper cups were ‘clean’. Rooney has several more articles in process and will be speaking at our BioCycle conference this September. Her presentation at the BioCycle conference is the third article in the library. Here she presents the data on biosolids concentrations. While the concentration in most biosolids products is higher than in the food waste composts, it is typically within the same ballpark. I have heard otherwise reasonable composters talk about whether they should still be composting food scraps as a result of this. I have also seen the actual impact and fear of the potential impact upset many biosolids program managers.
The 4th article in the library puts this ‘hysteria’ into some perspective. Unlike the biosolids produced in Alabama, where a factory that made these compounds was discharging into the sewer system, the source of this family of compounds for the vast majority of composts and biosolids is our homes. The 4th article looked at concentration of these compounds in the blood of women of color and non-Hispanic white women in California. ALL OF THE WOMEN TESTED HAD DETECTABLE CONCENTRATIONS OF THESE COMPOUNDS IN THEIR BLOOD. The article doesn’t mention biosolids or composts as an exposure route, but it does focus on common routes of household exposure. In the literature review the researchers note that a previous study found a connection between wearing rain coats and blood PFAS concentrations. Another study found a link between the length of time kids slept in carpeted rooms and blood PFAS concentrations. For this study they asked the women about certain behavior, including what type of pans they cook with, whether they eat seafood, their source of drinking water and whether they floss their teeth. That is correct. The authors found that use of non-stick cookware (p 0.86) was the best correlated with blood PFAS concentrations. Next up was eating seafood which is often high in PFAS (p 0.72). Flossing came in third (p 0.55). It turns out that Glide dental floss contains PFAS. Talk about a direct exposure route! Water supply had a p value of 0.44. Other factors, also significant but with lower p values, included eating microwave popcorn, using coated carboard containers and stain-resistant carpet.
In other words, these compounds are in biosolids and composts because they are ubiquitous in our homes. If we want to lower the concentrations in biosolids, we should ban the compounds as we have done with the parent compounds. Prohibiting or severely restricting use of composts or biosolids because of these compounds will have no impact on human exposure.
So how can we calm the hysteria? Perhaps with a bit of perspective and common sense. That is what we did to put concentrations of pharmaceuticals and personal care products in biosolids into a reasonable perspective (Article 5). Remember those good old days when people were worried about pharmaceuticals? We calculated how many days of exposure to biosolids it would take to equal a recommended daily dose of select drugs or daily home exposure to plastics and personal care products. We used standard EPA methods, a range of potential exposure pathways, did a detailed literature search to get appropriate biosolids and compost concentrations and daily home exposure estimates. We looked for plant uptake as an exposure route (and didn’t find any). We considered drinking water contaminated by biosolids. We even did a survey of a range of biosolids to get actual real-world concentrations from small towns and big cities. Finally, we expressed the exposure from biosolids to home exposure in ways that the lay public and can understand. Below is one of the figures from the paper.
In addition to the peer reviewed version of this article, I recently wrote up an easier to read version that is open access in BioCycle magazine-
https://www.biocycle.net/2019/05/06/revisiting-reframing-risk/. No need to put this in the library, as you can just click on the link and see it for yourself.
So, what would happen if you used the same approach to communicate the potential exposure to PFAS in biosolids to common household exposure? I came up with a few attempts - dental floss and chocolate cake compared to biosolids compost…
Which product should you choose if you want to be safe from exposure? The safest product is clearly the BIOSOLIDS product!
Sally Brown, University of Washington