The brain is the main target for Sulfuryl fluoride.
Sulfuryl fluoride’s use as a food fumigant on post-harvest food was first approved by the US EPA Office of Pesticides in 2004. With this approval, EPA approved the highest levels of fluoride residues on food in its history. According to EPA, Sulfuryl fluoride breaks down rapidly in the human body to fluoride.
A study finds that the pesticide sulfuryl fluoride, used for insect (i.e., termites, bedbugs, cockroaches, etc.) fumigation treatments, increases greenhouse gas (GHG) emissions, according to the report, “Termite Fumigation in California Is Fueling the Rise of a Rare Greenhouse Gas.” Not only do most sulfuryl fluoride emissions in the U.S. occur in California, but a majority of global emissions also occur in California. When the use of methyl bromide for agricultural and structural fumigation was phased-out under the Montreal Protocol, sulfuryl fluoride became a replacement for fumigation treatments. However, researchers have identified concentrations of sulfuryl fluoride in the atmosphere due to the chemical’s long half-life and greenhouse warming potential (GWP). The California Global Warming Solutions Act of 2006 does not list sulfuryl fluoride emissions as a GHG risk. Therefore, the researchers note, “This work emphasizes the importance of considering [sulfuryl fluoride] SO2F2 in state and national greenhouse gas inventories and emissions reduction strategies.”
Researchers employed geostatistical inverse model (GIM)—commonly used to estimate GHG fluxes—alongside atmospheric measurements of sulfuryl fluoride to estimate emissions throughout the United States. Using programmable flask packages (PFPs), researchers examined atmospheric observational data from towers, observatories, and aircraft, measuring concentrations of sulfuryl fluoride via gas chromatography-mass spectrometry. To compare surface and downwind emission, the researchers used the Lagrangian particle dispersion model (STILT) with multiple variables, including county-wide uses of sulfuryl fluoride and the U.S. Geographical Survey National Land Cover Database.
The GIM results demonstrate that most U.S. sulfuryl fluoride emissions derive from California, specifically the greater Los Angeles (LA) area (up to 400 parts per trillion between 2015 and 2017), followed by the Bay area. Moreover, all regions outside of California have negligible sulfuryl fluoride atmospheric concentrations, resulting in little to no emissions. Thus, the study implies California is the world’s leading sulfuryl fluoride emitter. Leading author Dylan Gaeta, a Ph.D. student at Johns Hopkins University, extrapolates, “We expected to see little splotches of emissions throughout at least some other parts of the country…The fact that we are seeing almost all of it from California? That was the shocking part.”
Sulfuryl fluoride is a fluoride compound with various adverse health effects, including cancer, endocrine disruption, neurotoxicity (reduced IQ), and reproductive damage. The Food Quality Protection Act (FQPA) amendments to Federal Food, Drug, and Cosmetic Act (FFDCA) require that a pesticide registered for use by the agency cannot exceed acceptable risk thresholds for both dietary and non-dietary exposure. However, a U.S. Environmental Protection Agency’s (EPA) peer-reviewed risk assessment of fluoride exposure finds that exposure to fluoride from various sources (i.e., sulfuryl fluoride residues in food commodities, fluoride exposure in water and toothpaste) did not meet the safety standard under FFDCA. Moreover, sulfuryl fluoride rapidly metabolizes (breaks down) in the body into fluoride. Considering the compound has a long half-life in human bones (~20 years), advocates attest EPA should withdraw the allowed tolerances for food uses of sulfuryl fluoride.
Sulfuryl fluoride, registered for termite and other wood-boring pest extermination in 1959, gained additional attention as a potential alternative to methyl bromide, a broad-spectrum insect fumigant used in post-harvest storage and food processing facilities. Methyl bromide’s designation as a greenhouse gas under the Montreal Protocol (2005) caused a gradual reduction in use. However, when no feasible methyl bromide alternatives are available, the “critical use exemption” (CUE) allows the use of this chemical. Furthermore, others (i.e., Natural Resources Defense Council) argue that the disallowance of any sulfuryl fluoride uses will lead to prolonged or increased methyl bromide use. However, Beyond Pesticides and others maintain that without the phase-out of sulfuryl fluoride, there will be no incentive for grain storage facilities to upgrade and adopt modern practices that forego hazardous chemical use. Although EPA decided to phase-out sulfuryl fluoride use on food commodities in 2011, Dow AgroScience (the manufacturer of sulfuryl fluoride under the trade names Vikane and ProFume), along with others lobbied against efforts to phase-out use, in the lead up to Congressional action to overrule the science on adverse health effects.
The U.S. Congress, in the 2014 Farm Bill (Agricultural Act of 2014), included a provision that requires EPA to ignore the science and law that establishes the safety threshold for exposure to fluoride. (See When Politics Trumps Science and Health Suffers.) The use of the pesticide sulfuryl fluoride, allowed in food production since 2004, in combination with fluoride use in water fluoridation, creates unacceptable hazards under EPA and National Academy of Sciences (NAS) scientific determinations. However, in an intervention that simply defies the scientific literature and thresholds for safety, the bill language orders EPA not to follow the law and science. The regulatory agencies responsible for protecting public health have identified elevated risk of dental fluorosis (breaking down of teeth enamel) in young children, and possibly skeletal fluorosis (joint pain and muscle impairment), while the scientific literature raises serious issues of neurological and brain effects from elevated levels of fluoride.
The sulfuryl fluoride/GHG study represents an all too familiar pattern of widespread chemical use without proper knowledge of health and environmental effects before implementation. According to the most recent data by the California Department of Pesticide Regulations, sulfuryl fluoride is the 12th most used pesticide applied to sites across California, with over 2.9 million pounds used in 2018 for structural and agricultural pest control. Although sulfuryl fluoride emissions mainly stem from the greater Los Angeles area, researchers suggest other states, like Florida, may also produce emissions that remain unaccounted for by current National Oceanic and Atmospheric Administration (NOAA) chemical tracking. The California Air Resources Board (CARB) added sulfuryl fluoride to its list of “short-lived climate pollutants,” being the only state to do so since 1990. However, California does not include sulfuryl fluoride in the list of GHG emissions to reduce by 2020 as researchers were not aware the chemical was a GHG until 2008. A 2009 study finds the termite insecticide to be a more potent GHG than carbon dioxide by up to 4,000 times over 100 years. Since sulfuryl fluoride has high global warming potential, it can remain in the atmosphere for more than 36 years.
Ninety-nine percent of structural fumigation treatments use sulfuryl fluoride. Recent work from the Massachusetts Institute of Technology (MIT) demonstrates North America was the leading global source of sulfuryl fluoride emissions in 2019. The risk of multiple chemical contaminants in the atmosphere increases as global warming progresses. Melting glaciers can release persistent organic pollutants into waterways. Recently, pesticides and fertilizers overtook the fossil fuel industry in environmental sulfur emissions. Thus, health and environmental concerns will increase significantly, especially for individuals and ecosystems more vulnerable to the toxic effects of chemical exposure. If pesticide use and manufacturing are amplifying the impacts of the climate crisis, advocates argue that pesticide policy and regulation must address and eliminate chemical use. There are many viable alternatives to sulfuryl fluoride and methyl bromide fumigation. These alternatives include temperature manipulation, atmospheric controls, biological controls, and less toxic chemical controls (diatomaceous earth). Many existing commodity storage facilities are too old and outdated to prevent pest infestation. This ineffectiveness leads to a reliance on toxic fumigation. Thus, a clean, regularly-maintained storage or processing facility can easily keep facilities pest-free.
As the climate crisis continues, banned and current-use pesticides put human and animal health at risk upon release into the atmosphere and waterways. Lack of adequate persistent pesticide regulations highlights the need for better policies surrounding use. The European Union already bans sulfuryl fluoride from any food contact. Thus, a switch from chemical-intensive agriculture to regenerative organic agriculture can significantly reduce the threat of the climate crisis by eliminating toxic, petroleum-based pesticide use, building soil health, and sequestering carbon. Current organic food production and handling do not permit conventional pesticide use, including fumigants like sulfuryl fluoride. Therefore, organic production reduces greenhouse gas emissions from chemical use. Learn more about how switching to organic management practices can mitigate the climate crisis by reading Regenerative Organic Agriculture and Climate Change: A Down-to-Earth Solution to Global Warming. For more information about organic food production, visit Beyond Pesticides’ Keep Organic Strong webpage. Learn more about the adverse effects chemical-intensive farming poses for various crops and how eating organic produce reduces pesticide exposure and benefits the environment.
All unattributed positions and opinions in this piece are those of Beyond Pesticides.