But more than the pesticides we found in the bottles, what shocked us was that there are no regulations for pesticide residues in bottled water in the country. Or put another way, the regulations are weak and ambiguous, giving enough space to manufacturers, to use the norm as a loophole. The Prevention of Food Adulteration Act (PFA) – under the Ministry of Health and Family Welfare – which lays down the standards, and the Bureau of Indian Standards (BIS) regulations – which certify the companies only says that "pesticide residues should be below detectable limits". The BIS then goes on to mandate a methodology for detection, which is not sensitive and would allow high levels of residues to be present in water legally.

Interesting, this when the BIS norm for pesticide residue in drinking water says that these should be "absent". Why, then was it diluted and fudged for the 1000-crore industry? The business of food safety regulation is a serious business. It requires a high order of scientific competence and integrity – both singularly lacking in this case.

Our study has had impact. There is general outrage and shock at the findings. The government has not only set up an enquiry, but also already announced that it will make the norms as stringent as the EU. But that being said, there is still enormous work to be done by all of us.

One key issue is to understand better the impact of ingesting small – possibly miniscule quantifies of toxins – on our bodies. It is clear that this is not about immediate health effects. This is about chronic toxicity and therefore, what we need to learn is how pesticides would slowly, invisibly damage and hurt the body’s immunity or lead to other health disorders.

We know that these pesticides – and we found DDT, lindane (gamma HCH), malathion and chlorpyrifos – have been individually indicated. There is evidence that lifetime exposure to DDT, for instance, induced liver tumours in rats; malathion is a known mutagen, rats exposed to lindane have shown evidence of liver cancer and that chlorpyrifos is a suspected neuroteratogen.

But how much is safe? The government-manufacturer combine find it easy to dismiss concerns by arguing that not enough is know about their impacts. They hide behind the uncertainty – however deadly its implications. It is for this reason that we have to do more, much more, to understand the impacts of these deadly substances on our bodies. This is exactly what we found in our work on air pollution and what we find today in the growing concern over the use of plastics. We need to invest in science for ecological and health security as much as we invest in modern industrial products.

But even as we search for the complete truth, one thing is certain: Regulations have to be based on a combination of science and precaution, so that we ensure that public health is not jeopardised. This is the lesson of environmental health.