ABERCO Tellitgrams (c)
Propylene Oxide (PPO)
The New Old Fumigant
Many years ago when I was selling emulsifiers to polymer chemists, I found that they always received information about new products with interest. They wanted to stay on the cutting edge of technology. However, new products were far between and besides many developed production problems. Others did not live up to expectations. For this reason I began a "Product of the Month" campaign in which old familiar products were featured with dressed up literature and enthusiasm. It was remarkably successful. People forget and these were new products to the ever changing laboratory personnel. It is this same situation I find now for the 40 year old fumigant, propylene oxide.
100% propylene oxide is a class 3 volatile flammable liquid, requiring the placing of commodities in huge vacuum chambers and all the air removed before PPO is injected. This eliminates any flammable hazard. After treatment the product is then aerated until the very volatile PPO residues are below the EPA established 300 ppm residue "tolerance".ABERCO's EPA approval label allows for the sale of propylene oxide "as an insecticidal fumigant" and "to reduce the bacterial and mold contamination in processed spices, cocoa powder and processed nutmeats (except peanuts)." Residual propylene oxide can be no more than 300 PPM in treated foods. Usually residues are less than 5 PPM or nonexistent by the time it reaches the consumer. PPO just evaporates off.
Propylene oxide is used by the billions of pounds per year to make propylene glycol, a food additive Generally Regarded As Safe (GRAS). This is done by reacting propylene oxide with water using acid as a catalyst. The lower the pH, the faster the reaction. Since human stomach acid has a very low pH of 1, the calculated half life of PPO in the stomach is about 60 seconds, a fact confirmed by recent ABERCO test using the U.S. Pharmacopeia's simulated stomach juice formula and radio labeled propylene oxide. Because propylene oxide has low toxicity, we feel it would be very difficult to find a safer insecticide as human stomach juice would instantly convert any PPO residues to the harmless glycol. The conversion to propylene glycol also takes place in ground water or in the air, but at a slower rate. These facts should make propylene oxide an environmentalist's dream.
When the MeBr situation struck, it was logical that our nut and cocoa customers ask if PPO could be used to replace MeBr to kill insects in raw cocoa beans and inshell nuts. After all, they reasoned, there is already an EPA tolerance (residue allowance) of 300 PPM for the edible part of these commodities. Furthermore, cocoa beans are roasted at high temperatures that are sure to destroy any PPO residues. Naturally, we thought this was a great idea but there were two problems: 1) They want to use it under ambient atmospheric conditions, and 2) there was no insecticidal efficacy data in the literature.
Propylene oxide is known to be an excellent insecticide by killing all stages of the Confused Flour Beetle, Indian Meal Moth, and Warehouse Beetle. These tests were conducted in vacuum chambers at concentrations ranging from 0.6 lbs to 1.2 lbs propylene oxide per 1000 cubic foot of sterilizer space. ABERCO is continuing these tests to determine the optimum dose/time ratios for maximum efficiency.
ABERCO hopes to extend the present registration to allow for insecticidal fumigation of cocoa beans and inshell nuts, then offer the nonflammable mix in cylinders for atmospheric fumigation. We think the time has come to return to a safe well known old product to solve this new problem.
Propylene oxide might just become the "Product of the Century".
[Home] [Propylene_Oxide] [News_Releases] [Research] [Contact_Information] [Company_Profile] [Help]