The UN Environment Programme (UNEP) on Thursday warned governments against use of methyl bromide, which could have hinder the global bid to repair the atmospheric ozone layer that filters out harmful levels of the sun's ultra-violet rays.
"We are urging countries today to redouble efforts to assess the quantities of an ozone-damaging chemical being used to kill pests on shipments of rice, maize, nuts and other big commodity export crops," UNEP said in a statement.
"Significant knowledge gaps exist on the true levels of methyl bromide being used around the world," the statement quoted UNEP chief Klaus Toepfer as saying on the International Day for the Preservation of the Ozone Layer.
"This could have implications for the global effort to repair the 20-mile high ozone layer, which filters out harmful levels of the sun's ultra-violet rays," Toepfer said.
Methyl bromide pesticide, one of the major ozone depleting substances in use, is being phased out for some key agricultural purposes under international Montreal Protocol agreement, covering uses like fumigation of soils and pest control on farms.
But other pest-control purposes, involving exports of commodity crops, animal fodder, cut flowers, hides and consignments in wooden pallets, are exempted from the international phase out.
"The effort to repair the ozone layer has been one of the great environmental success stories, with scientists estimating that by the middle of the century and as a result of the phasing out of numerous ozone damaging chemicals, the layer will be repaired, but this is far from guaranteed," Toepfer said.
Under the Montreal Protocol, developed countries are required to end use of methyl bromide on farms by end of 2004, but some developed world farmers in Australia, Europe and North America have expressed concern that alternatives to the chemical could be either less effective and more expensive.
Their governments are thus seeking Critical Use Exemptions beyond 2005 deadline, which will be discussed again when countries meet in Prague, Czech Republic, in November.