Delhi health minister Harsh Vardhan has repeatedly appealed to mustard oil traders to destroy stocks or return the same to producers. But how is this to be done? While officials themselves seem cluesless on the best way of destroying adulterated oil, many traders have already emptied tins of mustard oil into gutters. In the absence of government sugestions, they say, it is the simplest and perhaps only way of destroying oil. However, environmentalists don't aprove of the the traders' step and say that this might have an adverse effect on the Yamuna's ecological balance.