both acceptable suitability benchmarks for solar cells. Development still needs to be made on optimizing the nanoparticle ink formation and device architecture before commercialization is possible, but commercial spray-on zinc phosphide solar cells may be possible within ten years. Pest control Rodenticide Metal phosphides have been used as rodenticides. A mixture of food and zinc phosphide is left where the rodents can eat it. The acid in the digestive system of the rodent reacts with the phosphide to generate toxic phosphine gas. This method of vermin control has possible use in places where rodents are immune to other common poisons. Other pesticides similar to zinc phosphide are aluminium phosphide and calcium phosphide. Zn3P2 + 6H+ → 3Zn++ + PH3 ↑ Zinc phosphide is typically added to rodent baits in amount of around 0.75-2%. Such baits have a strong, pungent garlic-like odor characteristic of phosphine liberated by hydrolysis. The odor attracts rodents, but has a repulsive effect on other animals; However, birds, notably wild turkeys, are not sensitive to the smell. The baits have to contain sufficient amount of zinc phosphide in sufficiently attractive food in order to kill rodents in a single serving; a sublethal dose may cause aversion towards zinc phosphide baits encountered by surviving rodents in the future. Rodenticide-grade zinc phosphide usually comes as a black powder containing 75% of zinc phosphide and 25% of antimony potassium tartrate, an emetic to cause vomiting if the material is accidentally ingested by humans or domestic animals. However, it is still effective against rats, mice, guinea pigs and rabbits, none of which have a vomiting reflex. Pest control in New Zealand The New Zealand Environmental Protection Authority has approved the import and manufacture of Microencapsulated Zinc Phosphide (MZP Paste) for the ground control of possums. The application was made by Pest Tech Limited, with support from Connovation Ltd, Lincoln University and the Animal Health Board. It will be used as an additional vertebrate poison in certain situations. Unlike 1080 poison, it cannot be used for aerial application. Safety Zinc phosphide is highly toxic, especially when ingested or inhaled. The reason for its toxicity is the release of phosphorus compounds, usually phosphine, when it reacts with water and acids. Phosphine is very toxic and, with trace amounts of P2H4, pyrophoric. Phosphine is also denser than air and may remain close to the ground without sufficient ventilation. References External links Zinc Phosphide Pesticide