BHT

BHT /oss/taxonomy/term/1719/all en Let's preserve rational thinking when it comes to preservatives /oss/article/controversial-science-food-health/lets-preserve-rational-thinking-when-it-comes-preservatives <a href="http://blogs.mcgill.ca/oss/?p=6934"><img alt="preservatives" height="150" src="http://blogs.mcgill.ca/oss/files/2014/11/preservatives-150x150.jpg" width="150" /></a>Open a box of old crackers or potato chips and a smell emerges. It isn’t pleasant. The same goes for that bottle of oil that’s been sitting in the cupboard for months. It’s the smell of rancid fat. Technically speaking, the smell, which consists of numerous compounds, is the result of oxidation. Simply put, that means fats have reacted with oxygen in the air causing them to break down into smaller molecules. Not only are these malodorous, detectable at an unbelievably low concentration of 1.5 picograms per liter of oil, they can have nasty health consequences. It is not a good idea to eat foods in which the fat has gone rancid. Annoyingly, it is the healthier, polyunsaturated fats, that are more prone to rancidity. These fats have multiple double bonds in their molecular structure, a feature that enhances reaction with oxygen. Initially the fats are converted to hydroperoxides which are unstable and decompose to yield compounds like vinyl ketone, nonadienal and malondialdehyde. On top of having very low odour thresholds, some of these, malondialdehyde specifically, can cross-link proteins and DNA molecules and that is bad news. Such an affront to DNA can trigger cancer. Knowledge of the mechanism of such oxidation reactions has led to the use of “antioxidants” that react with hydroproxides and prevent their breakdown. The most effective ones have the tongue twisting names of butylated hydroxytoluene (BHT) and butylated hydroxyl anisole (BHA) which are added to foods containing solid fats or oils such as shortenings, baked goods and cereals. These chemicals are not just randomly added, like all other food additives, their use is strictly regulated. Manufacturers can add BHA or BHT up to 0.02% of the weight of the fat in a food which is an amount determined by extensive studies on animals. Of course if you give enough of any chemical to a test animal something will eventually happen. For example, BHA can cause carcinomas in the forestomach of rodents at a dose of 230 mg per kg per day. Internet bloggers can parlay that into scaring consumers who are unaware of the principles of toxicology and species differences. Humans do not have a forestomach and human exposures are actually less than 0.1 mg/kg/day. So while BHA can indeed be declared to be an animal carcinogen, this has no relevance to humans. On the contrary, studies have shown that at concentrations of 125 ppm which is close to food additive levels, both BHA and BHT have anticarcinogenic properties. Not only have there been no studies correlating these additives with human cancer, rates of stomach cancer have ben significantly decreasing possibly due to the use of preservatives. <a href="http://blogs.mcgill.ca/oss/2014/11/28/lets-preserve-rational-thinking-when-it-comes-to-preservatives">Read more</a> Sat, 29 Nov 2014 04:28:38 +0000 Joe Schwarcz PhD 2216 at /oss The Precautionary Principle /oss/article/controversial-science-health-toxicity/precautionary-principle <a href="http://blogs.mcgill.ca/oss/?p=6697"><img alt="principle" height="150" src="http://blogs.mcgill.ca/oss/files/2014/06/principle-150x150.jpg" width="150" /></a>“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 ne applied to using the precautionary principle. <a href="http://blogs.mcgill.ca/oss/2014/06/27/the-precautionary-principle">Read more</a> Fri, 27 Jun 2014 14:37:06 +0000 Joe Schwarcz PhD 2160 at /oss