Dioxins in fish oil supplements survey - your questions answered

Dioxins and PCBs (polychlorinated biphenyls) are very persistent chemicals and so are widely present in the environment and in foods at very low levels. These chemicals can be washed into rivers and ultimately into the sea where fish can accumulate them, particularly in their livers.

Dioxins have never been produced intentionally. They may be formed as unwanted by-products in a variety of industrial processes and some domestic ones like household fires. The major industrial releases of dioxins are controlled under pollution prevention control measures. PCBs have been used since the early 1930s mainly in electrical equipment. The manufacture and general use of PCBs stopped in the 1970s and is no longer permitted in the UK. The only remaining use of PCBs in the UK is sealed inside some older electrical equipment. However, these PCBs must be phased out and destroyed under UK regulations.

Dioxins and PCBs have no immediate effect on health, even at the highest levels found in foods. The potential risks to health come from long term exposure to high levels. They can cause a wide range of effects in animals, including cancer and effects on the immune and reproductive systems. However, it appears people may be less sensitive.

The TDI is the amount that may be consumed every day over a lifetime without causing harm. Following a review in 2001, requested by the Agency, the Committee on Toxicity (COT) concluded that the Tolerable Daily Intake for dioxins and dioxin-like PCBs should be reduced from 10 picograms (pg) TEQ/kilogram (kg) bodyweight (bw) per day to 2 pg TEQ/kg bw/day.

The tolerable daily intake is the amount that may be consumed every day over a lifetime without causing harm. The levels in the body take many years to build up. Exceeding the TDI leads to a reduction in the protection built into this guideline, but does not necessarily result in an appreciable risk to health.

The UK TDI is in line with recent recommendations from other international expert committees:

• the EU Scientific Committee on Food (SCF) set a tolerable weekly intake (TWI) of 14 pg/kg bodyweight;
• the Joint Expert Committee on Food Additives (JECFA) of the Food and Agriculture Organization (FAO) and the World Health Organization (WHO) set a provisional tolerable monthly intake (PTMI) of 70 pg/kg bodyweight.

Animal fat in milk, meat, fish, eggs (and their products) is the main source of dioxins and PCBs in the diet. Animals and fish take up dioxins and PCBs present in their food and from any soil or sediment they may eat, which then passes into their milk, meat, fish and eggs, concentrating in the fat. The levels of dioxins and PCBs in any individual’s diet will vary depending on the amounts and types of foods they eat but we cannot avoid them completely. Even non-fatty foods such as potatoes contain dioxins and PCBs.

At the time of publication of the dioxin in fish oil supplements survey (June 2002), the Agency was not aware of any products that are fortified with fish oils. Products that are fortified with omega 3 fatty acids (these tend to be margarines) are of plant origin, not fish. Though these will contain some level of dioxins and PCBs they are not considered to make as significant a contribution to the total intake of dioxins and PCBs from the diet.

Note added in September 2004. There are now some products on the market fortified with fish oils containing omega 3 fatty acids.

The current samples were purchased during October 2000 to February 2002. Following analysis, the final report was received on 29 April 2002.

It is possible that manufacturers may have different sources of fish or refining methods, which would lead to different concentrations of dioxins and PCBs in different products. Treatment of oils or changes to the source of fish offer potential means of achieving reduction in the concentrations of dioxins and PCBs. In addition there may be differences in the recommended dose, which would effect the overall intake of dioxins and PCBs from fish oil supplements.

Most people should be able to get all the nutrients they require from a balanced diet without the need for supplements. The Agency recommends that people consume, as part of a balanced diet, two portions of fish, one of which should be oily. Vegetable sources of omega 3 include linseed and rape seed oil, however, recent evidence indicates that these sources are not as effective or as beneficial as fish oils.

Occasional intakes of dioxins and PCBs at the highest level should not present a cause for concern. However, prolonged intake of dioxins and PCBs at high levels should be avoided. Where consumers wish to take such supplements, there is a wide range of fish oil supplements available that have neither health nor consumer protection concerns. Fish liver and body oils are a rich source of certain long chain polyunsaturated fatty acids (PUFAs) and are also a source of vitamins A and D.

From 1 July 2002 it will be an offence to place on the market foodstuffs including fish oil supplements, that contain higher contaminant levels than those specified in the Annex to the Regulation.