Dioxin: what it is and where it is found

Dioxin is the common name for a toxic substance, tetrachlorodibenzo-p-dioxin (Tcdd), made up of chlorine, carbon, hydrogen and oxygen.Dioxins make up a group of chemicals. Their scientific name is “polychlorinated aromatic compounds”; they have similar structure, physical and chemical properties.They are formed as a result of chemical processes: natural phenomena (such as volcanic eruptions, forest fires) or of human origin (manufacture of chemicals, pesticides, steel, paints, emissions of unloaded gas and incinerators.

How can humans be exposed to dioxins?
Dioxins are found in the atmosphere, water and soil, in some foods. Man can be exposed to dioxins by working in industrial sectors in which these substances represent by-products, or by accidental events always linked to industry, or through food products of animal origin; overall, skin contact and inhalation represent very limited routes of exposure. The main absorption occurs through contaminated food.

In fact, dioxins are not soluble in water, but are very soluble in fats. As a result, they bind to sediments and organic materials in the environment and are absorbed by human and animal fatty tissues. They are also not biodegradable, so they can accumulate in the food chain.

What health effects does the consumption of dioxin-contaminated foods have?
Dioxins have a number of toxic and biochemical effects; some of them are included among the carcinogenic substances for humans. Tests on laboratory animals have shown a link between the absorption of dioxins and health disorders such as endometriosis (problem affecting the uterus), developmental problems, neurological disorders, reproductive system problems (drop in the number of spermatozoa , malformations), effects on the immune system. These effects may appear at levels of dioxin exposure that are significantly lower than those that cause an increased risk of cancer.

How do dioxins enter the food chain?
Dioxins can enter the diet through several ways. The contamination of the environment is mainly caused by the transport of emissions from different sources (waste incineration, chemical industries, traffic and so on) to the atmosphere and to the ground. Particular sources of pollution can create localized areas where contamination is greater.

Soil is a place of natural accumulation: in addition to atmospheric fallout, dioxins can accumulate due to sewage sludge, uncontrolled landfills, erosion from contaminated areas.

Atmospheric transport and relapse are the main source of pollution of leafy vegetables, pastures and forage. The leaves are then consumed directly by grazing animals or preserved to produce hay or silage (livestock food stored in special silos). The use of sludge as fertilizers can in some cases increase the dioxin exposure of animals.

Dioxins are concentrated in the fatty tissues of cattle, sheep, pigs, poultry and seafood. In principle, the longer the life span of the animal, the easier it is for dioxins to accumulate in its organism.

What are the most at risk foods?
In general, foods of animal origin all contribute 80% of global human exposure to dioxins together. Contamination can vary widely depending on the origin of the food. Meat, eggs, milk and dairy products, farmed fish can have higher dioxin levels due to the dioxin present in feed.

The dose of dioxin absorbed individually varies greatly depending on the type of diet followed. For example, a diet focused on only one type of food from highly polluted areas (such as Baltic fish) will entail greater exposure than a diet rich in foods of vegetable origin and in general very varied.

What practical advice can be given to reduce the absorption of dioxin as much as possible?
As we have seen, the problem is generalized. It is therefore not a question of excluding this or that food, but of organizing one’s daily diet well.

In principle, the tips that can be followed are the same that generally make one’s diet healthier:
• reduce the consumption of food of animal origin (meat, dairy products, eggs), favoring vegetables and fruit, legumes (beans, peas, lentils, chickpeas) and cereals (pasta, rice, corn);
• vary your diet, so as to introduce many different foods. Since dioxins accumulate in fats it is also good to try to maintain a healthy weight.

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