Dioxins are a group of organic compounds that are structurally related to the highly toxic PCDDs (polychlorinated dibenzodioxins).
Dioxins are not made intentionally but are produced as by-products of a variety of human industrial activities. Processes such as smelting, choline bleaching of paper pulp and the manufacturing of herbicides and pesticides contribute to dioxin pollution. Incinerators with incomplete burning such as hospital incinerators are major producers of dioxins (see Waste Management)
Dioxins are then introduced to humans through their diets. More than 90% of human exposure to dioxins is through meat, dairy and seafood products. Once in in the environment, dioxins easily accumulate in the fats and oils in wildlife, especially fishes. From there, dioxins are concentrated throughout the food chain. Dioxins enter the human food sources primarily through contaminated animal feed.
To humans, dioxins are a major threat, causing skin diseases, immunological disorders, hormonal disorders, cancer and birth defects. People are at greater risk if they work with some kinds of chemicals (especially herbicides) or live near major sources of emissions that contain dioxins.
Also at higher risk are developing fetuses and breastfeeding infants who can receive dioxins via their mothers’ blood or milk.
The World Health Organization (WHO) says all people have some dioxins in their tissues, but for most people this will be at very low levels.
A group of dioxin-like chemicals called PCBs are also sometimes referred to as dioxins but they are covered in their own Toolkit page (scroll down).
Dioxins are persistent organic pollutants (POPs) and, as such, they are subject to the Stockholm Convention, which obliges countries to eliminate where possible, and minimize where not possible, all sources of dioxins.
Dioxin emissions from incinerators can be greatly reduced by ensuring complete combustion and by rapidly cooling the emissions just as they leave the chimney (known as quenching).
Many countries now monitor their food supply for traces of dioxins and can act to reduce any threats if they detect excessive levels.
As most food-related exposures are due to contaminated animal feed, the Codex Alimentarius Commission has developed a code of practice to reduce this threat.
In industrialized countries scientists have assessed the sources of dioxins and imposed of dioxins in people’s bodies, but this information is generally lacking in developing nations.
Dioxins are a difficult issue for journalists to report on as it is not easy to prove that any of the associated health problems are a direct result of a particular source of pollution.
Even when it is well known that a large exposure to dioxins has occurred, as in the case of the Seveso chemical disaster (FIX LINK), or the use U.S. Army’s use of Agent Orange in the Vietnam War (see Warfare), it is still not easy to directly show a link between dioxins and health effects in individual people.
It is also very difficult to prove that dioxins are even present as the cost of analyzing samples is very high and only a few laboratories in the world can do this work.
Despite this, such large-scale exposures are themselves are rich sources of strong human stories.
Journalists can also investigate what parties to the Stockholm Convention are doing to minimize or eliminate emissions of dioxins.
As incinerators are the major emitter of dioxins, journalists can investigate how they are controlling emissions – and whether they are seeking or receiving assistance from government or international agencies to do so.
Journalists can also investigate how dioxin levels in food are regulated and monitored by their national authorities, as this is the main source of exposure.
For this kind of reporting, the World Health Organization’s Food Contamination Monitoring and Assessment Programme is a useful source of contacts and information about each of the 70 countries it operates in.
World Health Organization – Dioxins and human health
EJNet Dioxin page – A comprehensive review of dioxins