Chemical Safety

Dioxins, May 2010


Key Facts

  • Dioxins are a group of chemically related compounds that are persistent environmental pollutants.
  • Dioxins are found throughout the world in the environment and they accumulate in the food chain, mainly in the fatty tissue of animals.
  • More than 90% of human exposure is through food, mainly meat and dairy products, fish and shellfish. Many national authorities have programmes in place to monitor the food supply.
  • Dioxins are highly toxic and can cause reproductive and developmental problems, damage the immune system, interfere with hormones and also cause cancer.
  • Due to the omnipresence of dioxins, all people have background exposure, which is not expected to affect human health. However, due to the highly toxic potential of this class of compounds, efforts need to be undertaken to reduce current background exposure.
  • Prevention or reduction of human exposure is best done via source-directed measures, i.e. strict control of industrial processes to reduce formation of dioxins as much as possible.

Background

  • Dioxins are environmental pollutants. They have the dubious distinction of belonging to the “dirty dozen” – a group of dangerous chemicals known as persistent organic pollutants.
  • Dioxins are of concern because of their highly toxic potential. Experiments have shown they affect a number of organs and systems.
  • Once dioxins have entered the body, they endure a long time because of their chemical stability and their ability to be absorbed by fat tissue, where they are then stored in the body.
  • Their half-life in the body is estimated to be seven to eleven years. In the environment, dioxins tend to accumulate in the food chain. The higher in the animal food chain one goes, the higher the concentration of dioxins.

Sources of dioxin contamination

  • Dioxins are unwanted by-products of a wide range of manufacturing processes including smelting, chlorine bleaching of paper pulp and the manufacturing of some herbicides and pesticides.
  • They can also result from natural processes, such as volcanic eruptions and forest fires.
  • In terms of dioxin release into the environment, uncontrolled waste incinerators (solid waste and hospital waste) are often the worst culprits, due to incomplete burning. Technology is available that allows for controlled waste incineration with low emissions.
  • Dioxins are found throughout the world in the environment. The highest levels of these compounds are found in some soils, sediments and food, especially dairy products, meat, fish and shellfish. Very low levels are found in plants, water and air.

Effects of dioxins on human health

  • Short-term exposure of humans to high levels of dioxins may result in skin lesions, such as chloracne and patchy darkening of the skin, and altered liver function.
  • Long-term exposure is linked to impairment of the immune system, the developing nervous system, the endocrine system and reproductive functions.
  • Due to the omnipresence of dioxins, all people have background exposure and a certain level of dioxins in their body, leading to the so-called body burden.
  • Current normal background exposure is not expected to affect human health on average. However, due to the high toxic potential of this class of compounds, efforts need to be undertaken to reduce current background exposure.

Dioxin contamination incidents

  • Many countries monitor their food supply for dioxins. This has led to early detection of contamination and has often prevented impact on a larger scale.
  • One example is the detection of increased dioxin levels in milk in 2004 in the Netherlands, traced to clay used in the production of the animal feed.
  • In another incident, elevated dioxin levels were detected in animal feed in the Netherlands in 2006 and the source was identified as contaminated fat used in the production of the feed.
  • Some dioxin contamination events have been more significant, with broader implications in many countries.
  • In late 2008, Ireland recalled many tons of pork meat and pork products when up to 200 times more dioxins than the safe limit were detected in samples of pork.
  • This finding led to one of the largest food recalls related to a chemical contamination. Risk assessments performed by Ireland indicated no public health concern. The contamination was traced back to contaminated feed.
  • In July 2007, the European Commission issued a health warning to its Member States after high levels of dioxins were detected in a food additive, guar gum, used as thickener in small quantities in meat, dairy, dessert or delicatessen products. The source was traced to guar gum from India that was contaminated with pentachlorophenol (PCP), a pesticide no longer in use. PCP contains dioxins as contamination.
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