Dispersant Corexit 9500 was used on the Deepwater Horizon oil spill. Pemex contracted Conair Aviation to spray the chemical dispersant Corexit 9527 on the oil. PPG is used as a surfactant, wetting agent, dispersant in leather finishing. It also is used as an emulsifier and dispersant in topical preparations. Maritime New Zealand used the oil dispersant Corexit 9500 to help in the cleanup process. The primary dispersant used were Corexit 9527 and 9500, which were controversial due to toxicity. By 30 July 2010, more than of dispersant had been used, mostly Corexit 9500. In petroleum production, it can be used as a dispersant in oil well drilling muds. The oil and dispersant mixture permeated the food chain through zooplankton. The ratio of dispersant to oil is typically 1&colon;20. Studies have so far indicated that the dispersant is toxic to marine life. Researchers say the oil and dispersant mixture, including PAHs, permeated the food chain through zooplankton. Mucilage from prickly pear may work as a natural, non-toxic dispersant for oil spills. Some studies also show that too much lignosulfonate dispersant could result in a set-retarding effect. Officials requested that BP release information on their dispersant effects.