Of all the possible contaminating agents in food, dioxins are the ones people seem to worry most about. They appear in such small concentrations that they defy imagination, but their accumulation by ingestion is a health hazard. Although consumers do not know their toxic molecules, or what problems they cause, it is true that they fear them. But only part of this fear is scientifically justified. Only a few of the more than two hundred substances in this group carry a substantial risk. However, the most toxic ones require less than a millionth part of a gram to kill a guinea pig. This is why they are considered the most lethal artificial compounds man has ever synthesized, either intentionally or not.
Nevertheless, other animal species used in experiments are not quite as sensitive as guinea pigs to the toxic effects of dioxins. For example, for some rodents to die they require doses that are a thousand times higher. This is why, if we take this information as a point of reference, many of the most commonly used rat poisons and some pesticides are much more dangerous.
In short, part of the problem resides in determining if human beings are among the more or less sensitive species. But doubtless, the most worrying aspect of dioxins is not this, but their medium or long-term effects or possible effects. In particular, their capacity to cause fetal malformations or malignant tumours.
Dioxins do not have any practical application, because from the beginning it was seen that they were complicated to handle due to the high toxicity of some of their compounds. However, they are inadvertently manufactured during various industrial combustion processes that have to do with the creation or destruction of certain chlorinated compounds. The emissions from these processes make them end up in the environment, where they are very difficult to eliminate because they are extremely resistant to decomposition. Although the main source for the generation of dioxin is industrial, and the most important penetration route for humans is their release into the environment, they mostly accumulate through the food chain, especially in fats, due to eating contaminated foods.
The information available from studies performed in industrialized countries, including Spain, concludes that the median consumption is of 100 to 500 trillion parts of a gram of toxic equivalents per person per day. This amount does not seem like a lot, but we should not forget that these compounds are extraordinarily toxic and that, with substances that cause or may cause cancer, it is difficult to establish if a really safe dose exists. The basic rule in these cases is: less is best.
Can we do something to reduce our intake of these dangerous compounds? Of course, we may consult the published tables of dioxin levels classified by foods and choose the least contaminated ones. But even this way we will not be able to avoid them completely. It is always recommended to eat the most varied diet possible to diversify the risk and to try to reduce the ingested amount of different contaminants. The best thing to do is, of course, to support any environmental measure that tends to reduce emissions. These regulations have an economic cost and require sacrifices. Also, their beneficial effects are long-term. But whatever has been done in this direction in the last years, be it a lot or a little, it has already had an effect: our present intake is somewhat lower than what it was years ago.
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