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 only acceptable level of toxic substances in food is zero