Permitted Does Not Imply Safe: Why a legal limit is not the same as a safe dose, and how to read India's pesticide limits for drinking water against the world's

If my water is within the limit, is it safe? Why does the European Union allow one tenth of a microgram of malathion in a litre of drinking water while India allows 190? And who checks? This working paper answers those three questions by setting India's 18 pesticide limits for drinking water (IS 10500:2012) beside those of the World Health Organization, the European Union and the United States, each read in the original. It makes three claims. First, a permissible limit is not the same as a safe dose: two different kinds of number share the word 'limit'. Health-based limits divide a tolerable daily intake by assumptions about a 60 kg adult drinking 2 litres a day; the European limit is a purity rule that applies the same 0.1 µg/L to every pesticide, whatever its toxicity. Second, India is looser than Europe on 14 of its 18 pesticides, by up to 1,900 times, and matches or beats Europe only on four persistent organochlorines of the past; for ten of the 18 the WHO sets no guideline value, often because it judges them unlikely to occur, a judgment India's own measurements contradict. Third, a limit is only as real as the laboratory that can see it: India's drinking-water mission tests pesticides at state laboratories only, and the national pollution board reports 'below detection limit' without saying what the limit is. Every limit can be read with four plain questions, and the paper sets them out.