The site is no longer being updated, including the FSnet archives, but remains a vast source of food safety information. For current information, please visit the iFSN successor, bites, at

Chronically Overexposed and at Risk: Zeroing in on Zero Tolerance

12.may.03, Janna Schurer, Commentary from the Food Safety Network

12.may.03, Janna Schurer, Commentary from the Food Safety Network
Canadians are, according to a new report by Environmental Defence Canada, chronically overexposed to heavy metals and are at risk of developing heavy metal related health problems.
Yet the report, Metallic Lunch: An Analysis of Heavy Metals in the Canadian Diet, could also pass for another attempt to win media coverage by appealing to a public on the lookout for another Erin Brokovich scandal. According to this report, which analyzed data released by Health Canada, heavy metals in the food supply are putting the public at risk: "Lead, which can cause negative health effects no matter how little is consumed, is in the diets of Canadians of all ages." Scientific evidence, however, shows that while lead is a proven carcinogen, it also has an Acceptable Daily Intake (ADI), and the amounts of lead found in this study were all below the World Health Organization1s recommended limits.
It's a stretch to conclude that every Canadian is at risk of developing heavy-metal related illnesses. In establishing ADIs, toxicologists include many safeguards to ensure that even the most vulnerable person is safe. To put this in perspective, researchers have calculated that a child weighing 40 pounds would have to eat 30,000 pounds of carrots each day for a lifetime in order to be at risk for any adverse effects.
Yet a glance at news clippings from the past decade shows that Canadians are living in an age of fear-mongering and statistical manipulation. Politicians and activists alike are guilty of using the public to make emotionally charged decisions regarding the safety of the food supply. The result is that zero tolerance, previously a scientific term, has become nothing other than a buzzword for the media. Now, substitute pesticides for heavy metals and the result is the same slogan that organic farmers are using to promote their industry. Almost any pro-organic website will state that pesticide residues on non-organic produce are present at unsafe levels and that natural -- whatever that means -- is always better. A look at the evidence however, indicates otherwise.
Approval of pesticides for agricultural use generally takes 10 years and costs an average of $60 to $100 million. A 1994 study conducted by the Agriculture Canada and Canada's Agri-Food Safety Division found that the produce in Canadian supermarkets can be considered safe. Of the 22, 264 produce shipments that were sampled, 98.76 per cent to 100 per cent were below the allowable pesticide residue level; 75 per cent of those samples contained absolutely no detectable residue.
These numbers demonstrate that the rules governing chemicals for food, as well as the long and costly process to approve chemicals, are providing sufficient incentive for farmers to use pesticides sparingly. In considering whether natural is always better, it is important to realize that humans are not doing anything new by synthesizing pesticides. Tomato stems, rhubarb leaves and green potatoes are only three examples of plants that have developed extremely potent toxins as measures of defending themselves. Ironically, because such plants are more resistant to pests, they are also more likely to be grown by organic farmers. Canadians no longer live like the Ancient Athenians, who began testing food to ensure that wine and beer had not been watered down. Canadian chemists are able to find residues up to 0.3 parts per billion, surpassing our neighbours to the south who only recently upgraded their detection capacity to 1 ppb.
Ironically, coinciding with these dramatic improvements in detecting potentially harmful residues is the feeling that people are becoming less confident in the government1s ability to safeguard the food supply. Improvements to analytical techniques have resulted in scientists being able to detect much smaller amounts of residues than previously thought possible. And as a result, the term zero tolerance has in many ways become an empty phrase. Now more than ever, we should look back to Paracelsus, touted as the father of modern toxicology, who said, "All substances are poisons, the right dose differentiates a poison from a remedy."

Janna Schurer is a research assistant with the Food Safety Network in the
department of plant agriculture at the University of Guelph.