“When there is substantial, credible evidence of danger to human or environmental health, protective action should be taken despite continuing scientific uncertainty.” That’s the “Precautionary Principle” stated in its simplest format. Sounds like motherhood and apple pie. How can there even be a discussion about its application? But there is. That’s because “substantial, credible evidence” is open to interpretation and different countries approach the issue in different ways. Europe has introduced REACH, which stands for Registration, Evaluation, Authorisation and Restriction of Chemicals, a program that requires manufacturers to submit toxicity data to the European Chemical Agency before a chemical can be approved.
In the U.S., chemicals are governed by the Toxic Substances Control Act which is now under revision but historically has required proof of harm before acting on controlling a chemical. In Canada, chemicals are subject to the Chemicals Management Plan which is not quite as stringent as Europe’s REACH, but caters less to industry than U.S. regulations. The basic problem with all these regulations is that when it comes to the population being exposed to small amounts of chemicals, the data is very difficult to interpret. Occupational exposure, animal experiments and laboratory studies can provide clues but how relevant these data are to everyday human exposure is unclear. The most reasonable approach would be to weigh the need to use a certain chemical against toxicity data.
Consider food dyes as an example. While the data are not particularly compelling, there is some evidence that synthetics such as Red Dye No. 40, Yellow Dyes No. 5 and 6 may cause behavioural problems in some children and animal data suggest possible carcinogenicity. But different countries come to different conclusions about what to do. The U.K. Belgium, Switzerland, Denmark and France do not allow Red Dye No. 40, while Canada and the U.S. do. Here is a case where the precautionary principle should prevail. Food dyes are unnecessary, do not add anything in terms of nutrition and often make nutritionally poor foods more appealing. We don’t need them.
Bromates are another interesting case. When added to flour potassium bromate improves the baking qualities but is a suspected carcinogen. Bromates are not allowed in Europe or Canada but can be used in the U.S. because FDA says that they are destroyed during baking and only trace amounts remain. But if the rest of the world can get by quite nicely without adding bromates to flour, why can’t the U.S.? Because bromates make for the soft white texture and white colour that Americans have been goaded into preferring. Here too one can apply the precautionary principle. Remove bromates from flour.
However, when it comes to chemicals like preservatives, decisions become more difficult because these have obvious benefits. Theoretical risks for something like butylated hydroxyl toluene (BHT) or sodium nitrite have to be weighed against their demonstrated effects at keeping fat from going rancid or preventing botulism. The precautionary principle should also be applied to using the precautionary principle.