Abstract
From the report, pages 65-70:
Appendix C. Human Health Impacts of Fumigants.
Table 5. Sulfuryl Fluoride (SO2F2) summary
| Category | Description |
| Other names | Sulfuryl difluoride |
| Trade name(s) | ProFume® |
| Properties | Gas at room temperature, non-flammable, colorless, odorless |
| Primary use in post-harvest applications |
Pest control for stored food commodities (e.g., grains, nuts, and dried fruit) and nonfood commodities (e.g., logs). Applied in enclosed spaces, including storage facilities, warehouses, bins, silos, shipping containers, railcars, and within sealed tents/tarps. |
| Primary exposure route | Inhalation |
| Acute effects | Respiratory irritation, brain vacuoles, muscle twitching, seizures |
| Chronic effects | Dental fluorosis, inflammation of respiratory tissue, brain vacuoles, neurotoxicity |
| Air monitoring notes | Southern coastal regions of Los Angeles, Orange, and San Diego counties have the highest concentrations where commodity and structural fumigations are concentrated. |
| Regulatory status | Restricted Use Pesticide, Toxic Air Contaminant |
A. Background. Sulfuryl fluoride is a broad-spectrum fumigant used to control
pests that infest post-harvest food commodities, including beetles, moths,
weevils, and others. Sulfuryl fluoride is approved for the direct fumigation of
certain food commodities (e.g., rice, grains, nuts, dried fruit) and nonfood
items (e.g., logs, furniture). Its use is approved for food processing and storage
facilities (e.g., grain mills, warehouses, shipping containers). Sulfuryl fluoride is
an effective fumigant of stored commodities primarily due to its stability as a
gas at room temperature, high vapor pressure, and low molecular weight that
allow it to diffuse rapidly and penetrate porous materials. Sulfuryl fluoride was
first registered in the United States in 1959. However, its use greatly expanded
in post-harvest applications following the phaseout of methyl bromide in 2005.
Sulfuryl fluoride has become the primary alternative to methyl bromide for
treating post-harvest durable foodstuff in export and import trade.1
B. Exposure Pathways. Human exposure to sulfuryl fluoride from commodity
fumigation primarily occurs through inhalation and, to a lesser extent, ingestion
of fluoride residues on treated food. Studies measuring ambient sulfuryl fluoride
concentrations after commodity fumigations are limited. In a laboratory-based
study, 12% of fumigated commodities absorbed or retained high levels of sulfuryl
fluoride.2 Post-harvest studies measuring sulfuryl fluoride residues following
commodity fumigations show that minimal levels can persist after treatment and
aeration.3 Thus, residue tolerances have been established to minimize dietary
exposure from eating fumigated foods. Fumigators and commodity workers
who handle, store, and apply sulfuryl fluoride face the greatest risk of acute or
chronic health effects, especially if safety protocols are inadequately followed.
No warning agents are used in tandem with commodity fumigations using
sulfuryl fluoride. The fumigant is heavier than air, meaning it can pool at ground
level in enclosed spaces. Ventilation (e.g., fans, ventilation pipes) is essential to
reduce occupational exposures. Sulfuryl fluoride can penetrate porous materials
including bulk commodities and packaging material. During aeration, off-gassing
can pose an occupational inhalation risk. Nearby residents may also be exposed
through sulfuryl fluoride leaks from facilities during fumigations and from
aeration events immediately following.4,5
C. Health Effects: Sulfuryl fluoride is a toxic fumigant with documented adverse
neurotoxic and respiratory effects, and laboratory tests of genetic material
suggest it may damage DNA.4 The mechanism of toxicity of sulfuryl fluoride is
not fully understood. Upon inhalation, sulfuryl fluoride is rapidly absorbed and
hydrolyzed to fluorosulfate, sulfate, and fluoride in rats’ lungs.4 At sufficiently
high levels, fluoride ions can inhibit key cellular enzymes such as enolase,
disrupting cellular energy production from glucose (i.e., glycolysis) and cellular
energy production.6 Fluoride has been shown to induce oxidative stress in
toxicological studies at high concentration (greater than 100 ppm), though this
has not been demonstrated for sulfuryl fluoride.7 Most evidence of the adverse
health conditions from sulfuryl fluoride exposure comes from toxicological
studies, registrant data, and case reports of injuries and illnesses.
Acute health effects. Inhaling high concentrations of sulfuryl fluoride can cause a
range of immediate health effects, including death.11 In California, approximately
12 cases of sulfuryl fluoride-related injuries and accidents were reported from
post-harvest fumigations between 1992–2022.8 Symptoms following exposure
included headache, dizziness, nausea, vomiting, increased palpitations, and
irritation of eyes and throat.8 Other reports suggest that severe symptoms from
acute poisoning include pulmonary edema (fluid in lungs) and pneumonia,
as well as neurological issues such as headaches, dizziness, muscle twitching,
seizures, slurred speech, or confusion.9–11 Animal studies have demonstrated respiratory
effects, including inflammation in nasal passages, trachea, and bronchi
in rabbits and dogs; neurotoxicity (tremors, lethargy) in rodents, rabbits, and
dogs; cerebral lesions (vacuolation, malacia, and demyelination) in rabbits and
mice; and renal effects (papillary necrosis and degeneration and regeneration of
the collecting and proximal tubules) in rats.12–13
Chronic health effects. Chronic inhalation studies in rodents and dogs have
shown that sulfuryl fluoride exposure can affect multiple organ systems. In
animals and humans, the brain and respiratory tract are the main targets of
prolonged exposure, with neurological changes (vacuoles, lesions) and respiratory
tract inflammation.4 Renal effects, such as lesions and progressive glomerular
nephrosis have been reported in rats.4 Dental fluorosis (tooth discoloration
and enamel damage), reported in rat and dog studies, is consistent with accumulation
of fluoride ions in calcified tissues.4 Data on occupational studies of
sulfuryl fluoride inhalation exposure from post-harvest fumigations are limited.
However, among structural fumigation workers exposed to both sulfuryl fluoride
and methyl bromide, high sulfuryl fluoride exposure the prior year was linked
with poorer memory, and a trend of worse performance was observed with
increasing lifetime sulfuryl fluoride exposure. Workers with high sulfuryl fluoride
exposure also exhibited decreased olfactory function (sense of smell), suggesting
subclinical elevations of sulfuryl fluoride may act on the central nervous system.15
Sulfuryl fluoride is a respiratory irritant, and individuals with underlying respiratory
conditions are highly susceptible to lung damage from chronic exposure
to sulfuryl fluoride.4 Some laboratory studies of genetic material suggest that
sulfuryl fluoride may cause DNA damage at high doses, with speculation that
fluoride ions play a role in mediating its damage.3,4 However, studies of chronic
exposure in humans are lacking, and more research on its potential genotoxicity
are necessary to confirm this.
D. Air Monitoring. Nationally, California is the largest known emitter of
sulfuryl fluoride, releasing approximately 573,000 pounds (0.26 gigagrams)
annually, mostly from structural fumigations.16 The emissions from post-harvest
commodity fumigations are poorly understood. Sulfuryl fluoride exposure in the
environment varies by season, timing of fumigation, and location. The southern
coastal regions of Los Angeles, Orange, and San Diego Counties, where both
commodity and structural fumigations are heavily concentrated, have the highest
concentrations of ambient sulfuryl fluoride.16 While coarse studies on ambient
sulfuryl fluoride concentrations provide valuable insight, there are few studies
that have reported sulfuryl fluoride levels within or adjacent to food processing
and storage facilities. Sulfuryl fluoride is not included in the list of pesticides
being monitored by the California Department of Pesticide Regulation’s Air
Monitoring Network, although it is heavily used as a structural and commodity
fumigant in California. More workplace and environmental monitoring would
help determine whether local ambient concentrations pose a health risk,
especially for susceptible populations in Southern California.
E. Regulatory Context. Sulfuryl fluoride is federally classified as a Restricted
Use Pesticide, and only certified applicators may handle sulfuryl fluoride. In
California, sulfuryl fluoride is designated a Toxic Air Contaminant due to its
potential for human health risks. However, it is not federally recognized as
a Hazardous Air Pollutant, excluding it from the U.S. Clean Air Act emission
regulations. In July 2024, the U.S. Environmental Protection Agency updated
product labels for Vikane, the structural fumigant, with additional safety
measures for certified applicators, including expanded worker training, longer
aeration procedures, fumigation logs, and no-entry warning signs. Regulatory
agencies have established residue tolerance levels for foods fumigated with
sulfuryl fluoride to ensure foodstuffs are within safety margins.3 Additional data
on the potential effects of sulfuryl fluoride on post-harvest workers are lacking,
as their exposures may differ in volume, concentration and duration. Populations
living or working near fumigated sites may also be exposed to sulfuryl fluoride
via off-gassing and drift. Limited air monitoring data around fumigation facilities
highlight the need to further evaluate potential risks.
References (Sulfuryl Fluoride)
1. Tsai, W.T. (2010). Environmental and health risks of sulfuryl fluoride, a fumigant replacement
for methyl bromide. Journal of Environmental Science and Health, Part C, 28, 125–145.
https://doi.org/10.1080/10590501.2010.481806
2. Sriranjini, V.R., & Rajendran, S. (2008) Sorption of sulfuryl fluoride by food commodities. Pest
Manag Sci, 64(8), 873–879. https://scijournals.onlinelibrary.wiley.com/doi/10.1002/ps.1577
3. U.S. Environmental Protection Agency (EPA). (2025). Established Residue Tolerances for
Sulfuryl Fluoride (40 CFR § 180.575).
https://www.govinfo.gov/content/pkg/CFR-2024-title40-vol26/pdf/CFR-2024-title40-vol26-sec180-575.pdf
4. California Department of Pesticide Regulation (DPR). (2020). Sulfuryl Fluoride Sulfuryl
Addendum to the 2006 Risk Characterization Document: Update of the Toxicology
and Reference Concentrations.
https://www.cdpr.ca.gov/wp-content/uploads/2024/10/sulfuryl-fluoride_addendum.pdf
5. Friones, J.R. (2006). Findings of the Scientific Review Panel on the Proposed Identification
of Sulfuryl Fluoride as a Toxic Air Contaminant.
https://www.cdpr.ca.gov/wp-content/uploads/2024/11/srp_findings.pdf
6. Mendrala, A.L., et al. (2005). Rapid uptake, metabolism, and elimination of inhaled sulfuryl
fluoride fumigant by rats. Toxicological Sciences, 86(2), 239247.
https://doi.org/10.1093/toxsci/kfi196
7. Johnston, N.R., & Strobe, S.A. (2020). Principles of fluoride toxicity and the cellular
response: a review. Archives of Toxicology, 94(4), 105–1069.
https://doi.org/10.1007/s00204-020-02687-5
8. DPR. (2025). California Pesticide Illness Surveillance Program (PISP). California Department of
Pesticide Regulation. https://apps.cdpr.ca.gov/calpiq/
9. Scheuerman, E.H. (1986).Suicide by Exposure to Sulfuryl Fluoride. Journal of Forensic
Sciences, 31(3), 1154–1158. https://doi.org/10.1520/JFS11128J
10. Mulay, P.R., et al. (2016a). Acute Illness Associated with Exposure to a New Soil Fumigant
Containing Dimethyl Disulfide-Hillsborough County, Florida, 2014. Journal of Agromedicine,
21(4), 373–379. https://doi.org/10.1080/1059924x.2016.1211574
11. Schneir, A., et al. (2008). Systemic fluoride poisoning and death from inhalational exposure
to sulfuryl fluoride. Clinical Toxicology (Philadelphia, Pa.), 46(9), 850–854.
https://doi.org/10.1080/15563650801938662
12. California Office of Environmental Health Hazard Assessment (OEHHA). (2005). Findings on
the Health Effects of the Active Ingredient: Sulfuryl Fluoride. Pesticide and Environmental
Toxicology Section, Office of Environmental Health Hazard Assessment, California Environmental
Protection Agency.
https://oehha.ca.gov/sites/default/files/media/downloads/pesticides/report/sulfurylfluoridefindingsoehha2005.pdf
13. EPA. (2005). Human Health Risk Assessment for Sulfuryl Fluoride and Fluoride Anion
Addressing the Section 3 Registration of Sulfuryl Fluoride Fumigation of Food Processing
Facilities. Office of Prevention Pesticides and Toxic Substances.
https://downloads.regulations.gov/EPA-HQ-OPP-2005-0174-0009/content.pdf
14. Eisenbrandt, D.L., et al. (1989). Inhalation toxicity of sulfuryl fluoride in rats and
rabbits. Fundamental and Applied Toxicology, 12(3), 540–557.
https://doi.org/10.1016/0272-0590(89)90027-4
15. Calvert, G.M., et al. (1998). Health effects associated with sulfuryl fluoride and methyl
bromide exposure among structural fumigation workers. American Journal of Public
Health, 88(12), 1774–1780. https://doi.org/10.2105/ajph.88.12.1774
16. Gaeta, D.C., et al. (2024). California dominates U.S. emissions of the pesticide and potent
greenhouse gas sulfuryl fluoride. Communications Earth & Environment, (5)161.
https://www.nature.com/articles/s43247-024-01294-x