STRUCTURAL FUMIGATION: USING SULFURYL FLUORIDE

Transcription

1 STRUCTURAL FUMIGATION: USING SULFURYL FLUORIDE Introduction Definition: Sulfuryl fluoride (SO2F2), also known as Vikane, (99.8% by weight Sulfuryl fluoride and 0.2% inert) is a restricted-use pesticide developed by Dow Chemical in 1. the late 1950 s as a structural fumigant. Vikane possesses characteristics for the eradication of structure-infesting insects. It is non-flammable, non-corrosive, and does not cause any undesirable odors. It quickly penetrates structural material, is effective against a variety of structural pests, and dissipates rapidly during aeration. Past Use: Since first marketed in the U.S. in 1961, sulfuryl fluoride has been used to fumigate more than one million buildings including museums, historic landmarks, libraries containing rare books, government archives, scientific and medical research laboratories, and food-handling facilities All Star Training, Inc. 1

2 Effectiveness: Sulfuryl fluoride is an excellent broad-spectrum fumigant, due to its toxicity to target pests, good dispersion and penetrating qualities. It is commonly used to control a wide variety of household pests, including Dry Wood and Formosan termites, wood-boring beetles (powder post beetles, deathwatch beetles, and old house borers), fabric and museum pests (clothes moths and furniture and carpet beetles), ticks, and rodents (rats and mice) that infest buildings, furnishings, construction materials, and vehicles. Alternative to Methyl Bromide: Sulfuryl fluoride is an established structural fumigant, and therefore is considered an alternative to methyl bromide. Compared to methyl bromide, sulfuryl fluoride penetrates structural materials more rapidly, and is effective against a wide variety of pests, and leaves fewer residues in materials after aeration All Star Training, Inc. 2

3 Fumigant Qualities Compared with Methyl Bromide Unlike methyl bromide, sulfuryl fluoride does not react with sulfur-containing materials that form skunk-odors. Sulfuryl fluoride passes through nylon and polyethylene sheeting much more slowly than methyl bromide, so that the gas is easily confined by the plastic tarps commonly used in structural fumigation. Sulfuryl fluoride penetrates into and aerates 2. MethylBromide.htm from wood much faster than methyl bromide. Rapid penetration of substrates inhabited by the pests allows for variable (shorter) exposure times compared with standard exposure times for methyl bromide. Sulfuryl fluoride is about 20 times less soluble in water than methyl bromide allowing water to be used as a barrier during the fumigation process. Efficacy: Sulfuryl fluoride is highly toxic to all post-embryonic life stages of insects. Eggs of most species are less susceptible All Star Training, Inc. 3

4 Measurement: The efficacy of sulfuryl fluoride depends on the concentration reaching the target pest and the duration of exposure. As a result, the dosage of sulfuryl fluoride required for a specific pest is calculated in ounce-hours, ounces of sulfuryl fluoride multiplied by hours of exposure. Calculation: Fumigators use a fumiguide calculation system to determine the amount of sulfuryl fluoride required for specific pest and fumigation conditions. Use against Insect Eggs: In general, insect eggs require a higher ounce-hour of dosage compared to later life stages (i.e. a 10-fold increase in dosage for some insect species). A Note on Social Insects: The ability to control egg stages of social insects (i.e. termites and ants) is not necessary because these newly hatched larvae cannot survive without adult care. Compensation: 2014 All Star Training, Inc. 4

5 The higher dosages required to control insect eggs can be obtained by increasing the exposure time, concentration of sulfuryl fluoride, or a combination of the two. Cause of Death: Sulfuryl fluoride prevents insects from metabolizing the 3. research/ecology_research/ecology_of_cum berland_plain_woodland/woodland_ecology /Processes_affecting_life_cycle stored fats they need to maintain a sufficient source of energy for survival by disrupting the glycol sis cycle. Death may be delayed for insects for several days following fumigation; therefore insects that have received a lethal exposure to sulfuryl fluoride may still be living immediately following fumigation (no longer than 3 to 5 days for termites). Sulfuryl fluoride has also been demonstrated to reduce oxygen uptake in insect eggs All Star Training, Inc. 5

6 Usage Registered Sites: Sulfuryl fluoride is currently registered to control pests in structures, fumigation chambers, construction materials & furnishings, and all vehicles except aircraft and subsurface water 4. www2.dpi.qld.gov.au/forestry/5026.html vessels. General Use: Sulfuryl fluoride is odorless, colorless, non-flammable, non-reactive, and noncorrosive at temperatures normally encountered in structural and other fumigations. As a result, it can be used to fumigate photographic supplies, metals, paper, leather rubbers, plastics, cloths, wallpapers, household furnishings, and a variety of other articles All Star Training, Inc. 6

7 Effects on Plants: Sulfuryl fluoride has little or no effect on the germination of weed and crop seeds; however, it is injurious to green plants, vegetables, fruits, and tubers. Surface Residue: Sulfuryl fluoride does not form toxic surface residues on household items thus dishes, cloths, and other items do not need to be removed or washed following fumigation. Foodstuffs: 5. ines/msad10may99_1.htm Sulfuryl fluoride is not registered for use where food and grain commodities are present because food residue tolerances have not been established. Guidelines for use of the fumigant specifically state that under no conditions should Vikane be used on raw agricultural food commodities, food, feeds, or medicinal products destined for human or animal consumption, or on living plants All Star Training, Inc. 7

8 Application Dosage: Because of a multitude of structural, environmental, and fumigation variations, no two fumigations are alike. The required dosages of sulfuryl fluoride are influenced by the temperature at the site of the pest, the length of the exposure period, containment or the rate the fumigant is 6. SC%20427/oh427.html lost from the structure, and the susceptibility of the pest to be controlled. Dosages vary, however a typical dry wood home fumigation uses 6-16 ounces ( lbs.) per thousand cubic feet. A specially designed Fumiguide calculator, which takes into account varying fumigation conditions (e.g., wind speed, relative humidity, tarp condition, volume in cubic feet being treated, soil type around the structure, target pest, fan capacity, and exposure duration), is used to determine the required fumigant dosage. Reaction to Heat: As with methyl bromide, exposing sulfuryl fluoride to open flames can form acids that may react with metals, glass, ceramic tiles, or china near the heat source All Star Training, Inc. 8

9 Thus, prior to structural fumigation, all open flames and glowing heat filaments are turned off or disconnected (i.e., pilot lights, electrical heater elements, or automatic switches). Administration: Sulfuryl fluoride is packaged in white cylinders as a liquid under pressure (99.8% Vikane with other pesticides, solvents, or additives); however, it volatizes rapidly upon release from the cylinder. Therefore, the gas is released under its own vapor pressure through tubing directly into the structure from pressurized cylinders. The release of sulfuryl fluoride is dense (3.5 times heavier than air), and will extract heat from the air as it changes from a liquid to a gas. Fans are used not only to distribute the gas throughout the fumigation area, but also to act as heat exchangers to mix cool air near the fumigation introduction site with surrounding warmer air to prevent condensation of moisture from the air. Unlike methyl bromide, no auxiliary heat source is required All Star Training, Inc. 9

10 Monitoring: Concentrations of Sulfuryl fluoride can be monitored during fumigation using a fumiscope. Because sulfuryl fluoride is odorless and does not irritate the eyes or skin, trace amounts of a warning agent (e.g. chloropicrin, which causes irritation to the eyes, tears, discomfort, and has a noticeable disagreeable pungent odor) are typically introduced into the structure prior to fumigation to act as a warning agent. Aeration: Once the fumigation is complete, the fumigator will return to the structure to conduct the aeration procedure the final step in fumigation. This requires proper ventilation and clearance of sulfuryl fluoride and the warning agent from a structure. According to the Occupational Safety and Health Administration 7. (OSHA) permissible exposure limit (PEL) and the American Conference of Governmental Industrial Hygienists (ACGIH) threshold limit value (TLV) for sulfuryl fluoride, the fumigator must aerate the structure so that the concentration is 5ppm or less prior to reentry. Reentry must be approved by trained and state All Star Training, Inc. 10

11 licensed/certified professionals. Because sulfuryl fluoride has a very high vapor pressure (potential to escape from the area) and a low boiling point (it is a gas at - 67 F), it will quickly diffuse from concentrations within a structure to the outside air where it rapidly dissipates to non-detectible levels. Ultraviolet radiation and reactions with solid particles in the atmosphere catalyze the down of sulfuryl fluoride. Ecological Concerns: The relatively small amounts of sulfuryl fluoride released are calculated to have virtually no impact on the global atmosphere or environment. It is broken down mainly through hydrolysis to release fluoride and sulfide ions. Because it is fully oxidized it does not interact with or contribute to local ozone formation. Furthermore, the relative contribution of sulfuryl fluoride to acid rain is infinitely small compared to massive amounts of sulfur released to the atmosphere from industry. Finally, Sulfuryl fluoride contains no chlorine or bromine and therefore does not contribute to stratospheric ozone depletion. Toxicity: Sulfuryl fluoride is a toxic gas that can be handled safely by trained professional fumigators. This gas (as well as methyl bromide) is acutely toxic to humans, 2014 All Star Training, Inc. 11

12 although the severity of toxicological effects is dependent of the exposure to high concentration and exposure duration. Mammalian toxicity by inhalation is about equal to that of methyl bromide All Star Training, Inc. 12

13 Symptoms Short-term Exposure: Short-term inhalation exposure to high concentrations may cause respiratory irritation followed by a pulmonary edema (an accumulation of fluid in the 8. lungs, which can cause death), nausea, abdominal pain, central nervous system depression, and numbness in the extremities. The short-term exposure limit should not exceed 10ppm. Long-term Exposure: Chronic long-term inhalation exposure to concentrations significantly above the threshold limit value (TLV) may result in Fluorosis (i.e., fluoride binding to the teeth and bones) because sulfuryl fluoride is converted to fluoride ion in the body. The threshold limit for sulfuryl fluoride is 5ppm for repeated eight-hour exposures five days per week. Precautions: In proper practice with this material there is no need for the operator to be exposed to the fumigant. In planning fumigation, care should be taken to eliminate the 2014 All Star Training, Inc. 13

14 possibility of anyone breathing any concentration. This is not only good general fumigation practice, but is also particularly important with sulfuryl fluoride because the standard respirator canister affords protection for a very short time, owing to the nature of the gas. According to the instructions on the label issued by the manufacturer, a special canister designed for sulfuryl fluoride and other acid gases is required. Protection from concentrations up to 32 g/m 3 for 15 minutes can be obtained with the appropriate canister. For higher concentrations of sulfuryl fluoride, or for longer periods of time, an air-supplied or self contained breathing apparatus should be used. Product Label: Always read and use according to the product label on any pesticide All Star Training, Inc. 14

15 First Aid: The manufacturers of sulfuryl fluoride supply a booklet giving detailed recommendations for first aid with suggestions to the physician. The following condensed information of first 9. aid is supplied on the manufacturer s label: Send for a doctor in case of accident. If a person should be overcome from breathing this gas, immediately place patient in fresh air, face downward, with head slightly below the level of the lungs. Keep warm. If breathing stops, give artificial respiration. NOTE TO PHYSICIAN: First symptoms expected are those of nausea, respiratory irritation and central nervous system depression; excitation may follow. Treat symptomatically. There is no known antidote All Star Training, Inc. 15