Would it be right for the government to abandon efforts to determine at what levels to allow toxic substances in our food supply? Only if it can reasonably be argued that the only acceptable level of toxic substances in food is zero. However, virtually all foods contain perfectly natural substances that are toxic but cause no harm because they do not occur in food in toxic concentrations. Furthermore, we can never be certain of having reduced the concentration of any substance to zero; all we can ever know is that it has been reduced to below the threshold of detection of current analytical methods. The main conclusion of the argument is that ['the only acceptable level of toxic substances in food is zero', 'the government should continue trying to determine acceptable levels for toxic substances in our food supply', 'the government needs to refine its methods of detecting toxic substances in our food supply', 'naturally occurring toxic substances in food present little danger because they rarely occur in toxic concentrations']