What is dioxin?
Dioxin is a substance sadly known for its extreme toxicity and persistent, capillary and ubiquitous distribution in the environment.
In its molecular formula two benzene rings can be recognized, joined by as many oxygen atoms and conjugated in various positions with chlorine molecules. Dioxin is part of a wider family of chemical compounds closely accumulated due to their characteristics and toxicity - dioxins and furans - which, although causing similar harmful effects, present a different degree of toxicity.
Acute and chronic poisoning
In common parlance, when one simply speaks dioxin, reference is generally made to TCDD (2, 3, 7, 8 tetrachloro-dibenzo-dioxin), the most toxic of all the substances belonging to the homonymous category and also known as dioxin of Seveso (in reference to the disaster that occurred in the homonymous city way back in 1976). In July of that year, following an accident in a plant responsible for the production of herbicides, huge quantities of dioxin were released, with very serious repercussions on the health of the inhabitants of the surrounding areas. Dioxin is in fact carcinogenic and as such, at appropriate concentrations, can cause various cancers - in particular lymphomas, liver and breast cancer - thyroid diseases, endometriosis, diabetes and damage to the immune system, hematopoietic and reproductive.
Another typical manifestation of acute dioxin poisoning is chloracne, similar to juvenile acne, manifested in any part of the body and at any age following massive exposure to the toxic.
The danger of dioxin has been confirmed not only by medical and scientific investigations but also by direct observation of the repercussions on the health of the inhabitants of Seveso and of the Vietnamese villages hit by the agent Orange, an extremely powerful defoliant containing dioxin and used by Americans in the conflict of 1964-1975.
Bioaccumulation
The danger of dioxin is increased by the long persistence in ecosystems ; transported by atmospheric currents, by virtue of its volatility, it falls into areas that are also very distant from the original one, contaminating the water and the ground, and then passing into animal feed and from here to humans.
In the body, being fat-soluble, dioxin concentrates and accumulates in adipose tissue; for man the half life varies from 7 to 11 years (this time frame is necessary to "dispose" 50% of the accumulated dose).
The phenomena of bioaccumulation, contamination on a global scale and elimination through mother's milk also suggest a possible and worrying possibility of trans-generational damage; the danger, therefore, could be concrete even at much lower doses than those considered carcinogenic or otherwise dangerous for health.
In any case, this is a danger that is probably not so serious in the short term (certainly less than the alarmism periodically raised by the media), but which we absolutely must not neglect to protect our future and that of our children.
Production and Pollution
Dioxin and analogues are of no practical use; as such they are not intentionally produced, but are formed during a series of chemical reactions. For example, they are produced as unwanted impurities during industrial processes of combustion in a chlorate environment, such as foundries, pulp bleaching, combustion of waste oils, domestic heating and road traffic.
Among the most important producers of dioxins are waste incinerators, especially when they burn plastic residues such as PVC and other chlorinated compounds. However, much depends on the technologies adopted and in recent years the release of dioxin from incinerators has been significantly reduced, at least in countries that have taken appropriate measures in this regard.
Despite this, the problem periodically returns to alarm consumers and staff in charge of food control, due to the media scoops and the strict measures adopted by the European Union, which set the maximum permitted levels of dioxin both in the human nutrition than in the animal one.
The food products most exposed to the risk of dioxin are the fat parts (in particular butter and fatty fish, such as the blue one and salmon), milk and its derivatives; an important role is played by the positioning in the animal's food chain and the degree of contamination of the areas responsible for its breeding.
