hot sun needs a shield A pesticide called methyl bromide is damaging the Earth's protective shield of ozone. Farmers use this pesticide to kill tiny worms called nematodes, bugs and weeds that can affect strawberries, tomatoes and flowers. It is now the third most important cause of ozone destruction, after CFCs and halons. Its use has doubled in six years [1] but now (2004), there's a campaign to convince US supermarkets to stop selling food grown or treated with methyl bromide.

But there is an alternative: methyl iodide which is no threat to the ozone shield [2]. Why aren't farmers using this instead?

[1] New Scientist, 11/12/99, 7; [2] New Scientist, 20/7/96, 9