Insecticidal gas

Methyl bromide is a fumigant insecticide that rapidly kills insects, mites, and nematodes. It penetrates substrates including soil and wood, it usually does not stain or taint commodities, and is noncorrosive and nonflammable. It has a boiling point of 3.6 °C and is colorless and odorless at concentrations used for fumigation. Chloropicrin is sometimes added at 2% as a warning indicator when this methyl bromide is used in structures. The mode of action is damage to nerve cell membranes, and it reacts with sulflhydryl groups in proteins. Insects usually die within 24 h of exposure, but mortality may be delayed 1-2 days. In 1992 itwas listed as an ozone-depleting substance under the Montreal Protocol on Substances that Deplete the Ozone Layer, and all developed countries are scheduled to eliminate the majority of their use of this chemical by 2005.

Sulfuryl fluoride is a fumigant gas used to control household, structural, and stored-product pests. This chemical is not combustible. It has a vapor pressure of 13 442 mmHg at 25 °C, and aboilingpointof —5.4 °C at 760 mmHg. The critical route of exposure is through inhalation and the threshold limit value is 5 ppm. Under practical conditions, sulfuryl fluoride is fully oxidized in the atmosphere and does not interact with ozone. It readily penetrates mostmaterials, and has no adverse affects on metals. Sulfuryl fluoride is odorless and colorless, and a small quantity of chloropicrin is used with it as a warning agent. Mode of action is by disrupting the glycolysis cycle, thereby depriving the animal's body of metabolic energy. Mortality may be delayed for several days, depending on the animal species.

Phosphine (hydrogen phosphine) is the common name for the active ingredient released from the metal phosphides, aluminum phosphide, and magnesium phosphide. This fumigant is highly toxic, and a concentration of 400 ppm is lethal to insects, humans, and other forms oflife. Itwill corrode metals and may ignite in air at concentrations above its flammable limit of 1.8%. Phosphine has a detectable odor for humans at concentrations as low as 0.018 ppm; normally the gas can be detected before it can cause serious effects. The mode of action includes the nervous system, paralysis of the spiracu-lar muscles to prevent respiration in insects, and the enzyme cytochrome oxidase system is attacked. Exposure periods of 1-5 days are necessary to control most insect pests.

51 Ways to Reduce Allergies

51 Ways to Reduce Allergies

Do you hate the spring? Do you run at the site of a dog or cat? Do you carry around tissues wherever you go? Youre not alone. 51 Ways to Reduce Allergies can help. Find all these tips and more Start putting those tissues away. Get Your Copy Of 51 Ways to Reduce Allergies Today.

Get My Free Ebook


Post a comment