Everything you need to know about Sulfuryl Fluoride
Everything you need to know about Sulfuryl Fluoride
Dow Chemical developed sulfuryl fluoride in the 1950’s to control drywood termites. It was then registered as an insecticide and rodenticide in 1959. This is everything you need to know about sulfuryl fluoride, sold in South Africa under the brand name ProFume® Fumigant Gas.
Sulfuryl fluoride is an odourless gas which is both nonflammable and non explodable. It is stable to store in a steel cylinder for up to 6 years. Although the chemical is in a gas state at atmospheric pressure, it is sold as a pressurized liquefied gas. This is everything you need to know about sulfuryl fluoride.
Background of sulfuryl fluoride fumigant gas
The Dow Chemical Company developed sulfuryl fluoride as a structural fumigant and marketed it as Vikane® in 1961. More than 3 million priceless structures such as cathedrals, historical landmarks and rare-book libraries as well as scientific and medical research laboratories containing highly sensitive electronic equipment have been successfully fumigated with sulfuryl fluoride.
Structure-infesting pests cause costly damage to older homes in warmer climates. Extensive damage from termites and wood-boring beetles may occur before the pests are even noted. Although South Africa’s brick and mortar homes may not collapse as a timber-built home in Florida, USA could, roof trusses, hardwood flooring, wooden bannisters, window frames and of course cupboards and furnishings are at risk to termites and woodborer in warm, humid zones such as Durban, KZN.
Tented fumigation using sulfuryl fluoride has thus far shown 100% efficacy through all life phases of these notorious, hard to reach pests. Cockroaches, rodents and bed-bugs are also eliminated with sulfuryl fluoride treatment.
Postharvest breakthrough with sulfuryl fluoride in 1990’s
Postharvest losses in the United States was estimated at $5 billion per year (Pimental 1991). Insects that infested grains, dried fruits and tree nuts in mills, warehouses and food storage facilities meant product losses. Traditionally, methyl bromide was used to combat postharvest pests but the ozone depleting character of methyl bromide required an alternate solution (per the Montreal Protocol).
In 1995, Dow AgroSciences formed partnerships with leading stored product researchers, fumigators and food industries around the world to evaluate and develop sulfuryl fluoride as a postharvest fumigant. It has proven an effective treatment for all life stages of pest in the postharvest sphere, including phosphine-resistant pests.
Sulfuryl fluoride in South Africa
Fumico is one of two licensed distributors of sulfuryl fluoride in South Africa. It is manufactured and sold under the brand name ProFume® Fumigant Gas. The first fumigation using ProFume was undertaken by us on 8 April 2019
Sulfuryl Fluoride Fumigant Gas
Practical Fumigation with Sulfuryl Fluoride
Uses of Sulfuryl Fluoride
Sulfuryl fluoride is introduced into structures as a gas which fills all air spaces in the enclosed area and penetrate cracks, crevices and pores in the wood. The gas penetrates materials quickly and rapidly but dissipates during the ventilation process. It has been widely used as a fumigant to kill both the eggs and adults of insects such as cockroaches, termites, beetles, moths and flies after exposure of 16–22 hours with a concentration range from 0.5 to 3.5 and 5–77 g m−3 for LD95 for adults and eggs, respectively. Sufuryl fluoride is also used (successfully) on postembryonic forms of fleas, rodents, ants, bees, wasps, spiders, millipedes, bedbugs, silverfish, springtails, earwigs, fire- brats, book lice, and brown dog ticks.
It is crucial to contain sulfuryl fluoride for a sufficient period of time so tenting is used around the structure during fumigation. Any opening is sealed (door frames, window frames, key locks or drainage pipes for example) using a specialized ‘Pink Tape‘. Traditional masking tapes or duct tape are too porous to contain sulfuryl fluoride molecules.
Mechanism of action of sulfuryl fluoride on pest infestations
Sulfuryl fluoride has a complex mode of action. It is thought to be toxic primarily through the action of the fluoride ion which it contains. It inhibits oxygen uptake, disturbs the normal phosphate balance, and inhibits hydrolysis (breakdown) of fatty acids. The fluoride ion in sulfuryl fluoride is thought to bind to calcium (leading to spasms and seizures) as well as potassium and magnesium. Enzymes which require a magnesium ion for their normal function are inhibited by sulfuryl fluoride; these enzymes include enolases (used to metabolize sugar) and ATPase, an enzyme that is important in cellular energy metabolism. The end result is that sulfuryl fluoride prevents stored fats from being utilized, and there is insufficient energy for survival.
You can read more about the chemical action and interactions of sulfuryl fluoride here: Fact Sheet from the Journal of Pesticide Reform
Toxicity management of sulfuryl fluoride
Sulfuryl fluoride is “an extremely hazardous gas.” The most straightforward demonstration of its acute toxicity are the classifications and restrictions placed on itsuse by the U.S. Environmental Protection Agency (EPA). EPA classifies sulfuryl fluoride as a restricted use pesticide. This means that the pesticide must be used by or under the supervision of a certified applicator who is wearing protective clothing. Sulfuryl fluoride is also labeled with the signal word “Danger” by EPA, meaning that it is in the most acutely toxic category of pesticides. Because of sulfuryl fluoride’s acute toxicity, all entrances to the fumigated areas must be posted with a skull and crossbones sign. No one is permitted in the treated area without self-contained breathing apparatus until it has been thoroughly ventilated according to approved procedures and concentrations of sulfuryl fluoride have been measured at less than 5 parts per million.
Efficacy of sulfuryl fluoride in South Africa
Since implementing sulfuryl fluoride in South Africa, we have had a 100% success rate in treating all life stages of pest and has even proven effective against phosphine resistant pests. We estimate over 60% of all fumigations are now undertaken with sulfuryl fluoride. Structural fumigation using sulfuryl fluoride is most cost effective as the quantity of gas required is significantly reduced. Read more When Pesticides No Longer Work
A global search for alternate fumigants for export markets
As methyl bromide is phased out globally, alternatives such as phosphine (PH3), ethyl formate (EF) used in quarantine procedures and ethanedinitrile (EDN) have been introduced in various global markets. Each alternative has distinct disadvantages though:
- EF has a high sorption rate and lower permeability because of its lower vapor pressure compared with other fumigants
- Phospine requires a longer fumigation time than MB or EDN and certain pests have become resistant to it.
- EDN is expensive, costing more than twice that of MB, without a significant difference in the treatment efficacy or convenience of use
ProFume Sulfuryl fluoride, however, has shown tangible efficacy in controlled studies such as this one:
The future of sulfuryl fluoride in South Africa
Aligned to the global trend to find more environmentally friendly fumigants, sulfuryl fluoride shows robust promise to replace methyl bromide for all structural fumigations and most postharvest pest management and ISPM15 export requirements.
To date, the efficacy of sulfuryl fluoride is 100% against all life stages of pest. Since it is effective against phosphine resistant pests, its use is warranted in postharvest applications where phosphine may have dominated a decade ago.
Structural fumigation with sulfuryl fluoride is definitively more cost effective than methyl bromide due to its sorption and penetration results. Postharvest use of sulfuryl fluoride is more expensive than methyl bromide, but its effectiveness offers a degree of quality assurance beyond MB.
As more global markets test and accept sulfuryl fluoride results in ISPM15 commodities, the use of sulfuryl fluoride in export markets will exponentially rise.
Within the food manufacturing industry where senstive electrical equipment forms part of automated manufacturing processes, sulfuryl fluoride is essential. Not only is it able to penetrate into the deep recesses of machinary, it does no damage to electrical components and will not effect the taste, colour or aroma of the product.
The use of sulfuryl fluoride is set to increase globally and in South Africa in the forseeable future.
