Think of a stretch of highway running a distance of 10 kilometres.
Now imagine one centimetre measured out on that stretch of road. That’s the equivalent of one part per million.
Or take one second of time out of the period running from 1977 to today, a period of 32 years. That’s one part per billion.
Those are the kinds of measurements that are routinely used by scientists and analysts establishing tolerance levels for food and grain contaminants.
To the average person, they seem unimaginably, perhaps unnecessarily, tiny.
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An infinitesimal trace of something bad can shut down a factory, result in a product being banned or bring international trade to a halt.
At a wheat industry conference in Saskatoon last week, one leading food safety expert questioned the value of being able to detect things at such tiny levels.
“It’s a bit of a mixed blessing,” said David Lineback of the Joint Institute of Food Safety and Applied Nutrition at the University of Maryland.
“It has enabled us to find more toxic materials, but now we are measuring them at such a low level they may or may not have significance …. The question is how relevant are those numbers.”
He said people consume more toxins each day in the normal diet that nature has provided than in any other way, such as food additives.
“The problem is, once we learn what’s in our food at such low concentrations, it worries consumers and there can be an over-reaction.”
The fear is that the ability to detect such minute amounts could result in unnecessary regulation.
Lineback was speaking during a session on food safety and security at the quadrennial International Wheat Quality Conference in Saskatoon.
Speakers from Canada, the United States and Europe talked about safety issues facing the wheat and wheat food industry and what it can do to provide quality assurance and confidence to consumers.
Lineback said the industry must figure out how to communicate to the average consumer what those numbers really mean and prevent unwarranted fear.
But that won’t be easy, he said, adding food safety and security isn’t necessarily a rational process.
“The science is rational, but as you begin to interpret the science and add in all the societal, political and regulatory factors, it all changes.”
Tom Nowicki, the Canadian Grain Commission’s grain safety program manager, said he is comfortable with the way the system of standards and tolerances works, covering pesticide residues, mycotoxins, heavy metals and radionuclides.
“The vast majority of tolerance limits these days are based on sound science,” he said.
There are times when importers use unnecessarily tight tolerances as a trade barrier, he added, but that’s the exception rather than the rule.
“For the most part, the limits are reasonable and countries have to justify them under international scientific standards,” he said.
“Sometimes we may not like them if we have trouble achieving them.”
Nowicki acknowledged that the extremely low concentrations being measured do lend themselves to distorted results and said grain buyers are becoming more demanding when it comes to safety assurances, requesting detailed documentation, specifications and guarantees.
The commission occasionally receives unusual requests, mainly from Third World countries, seeking assurances that grain is free from “narcotics” or “plague.”
