The National Food Agency has long been aware of the problem of dioxins in foodstuffs. As early as the beginning of the 1980s, dietary recommendations were introduced concerning fish with elevated levels of organochlorine environmental pollutants. Commercial and recreational fishermen and their families have been identified as possible risk groups with a high consumption of dioxin-contaminated fish. Among these, children and women in their childbearing years (including pregnant and nursing women) should limit their consumption of contaminated fish, such as Baltic Sea herring.
Dietary recommendations for groups at risk
Maximum limits for dioxins in food are one tool for measures against the sale of foodstuffs contaminated with high levels of dioxins. However, the limits do not prevent the groups at highest risk (girls and women of commercial- and recreational fishing families) from eating fish caught by their families. Following the dietary recommendations concerning contaminated fish will give these risk groups adequate protection from a high dioxin intake, at the same time as retaining the nutritional advantages of having fish in their diet. From a public health standpoint, the consumption of fish is generally beneficial. In Sweden the current recommended maximum consumption of Baltic Sea herring and salmon for children up to 18 years and women in childbearing age is 2-3 times per year. For other groups the recommended maximum consumption is once a week.
Decreased average dioxin intake
Emissions of dioxins from combustion processes and the chemical industry have been significant sources of contamination to Swedish foodstuff. Owing to decisive steps taken against emissions, today’s population is exposed to considerably lower levels of dioxins than in the beginning of the 1970s.
The National Food Agency’s investigations of dioxin intake from food suggest that the average intake has been more than halved over the past 15 years (Livsmedelsverket, 2012). The average dioxin level in breast milk, which is a measure of the dioxin concentration in a woman’s body during pregnancy, is less than one tenth of the levels measured in the 1970s in the Stockholm-Uppsala area (Norén and Meironyté, 2000; Lignell et al., 2012).
Low consumption of Baltic Sea herring
The average consumption of herring from the Baltic is at present low in Sweden. A National Food Agency dietary study from 2010 ("Riksmaten 2010") showed that adults in Sweden consumed Baltic herring on average two times per year (Livsmedelsverket, 2011). The average consumption of wild-caught Baltic salmon was less than one portion per year.
In 2007 it was estimated that 6% of Swedish women in the age group 18-45 consumed herring at least 2 times per month (Livsmedelsverket, 2011). This is considered as a high consumption which increases the risk of women exceeding the tolerable intake of dioxins (Livsmedelsverket, 2011). The current recommended maximum consumption of Baltic Sea herring and salmon for young women in Sweden is 2-3 times per year.
A dietary study of children in 2003 showed that more than 60% did not consume Baltic Sea herring at all (Livsmedelsverket, 2011). This can be compared with the recommended intake for this group of 2-3 times per year. About 5% of the children consumed this type of fish once a month or more (Livsmedelsverket, 2011).
Average intake one fourth to one half of the tolerable intake
In the EU, a tolerable weekly dioxin intake of 14 picogram (pg) WHO-TEQ/kg bodyweight has been set by the Scientific Committee on Food (SCF, 2001). The tolerable intake represents the level considered safe over a lifetime and is calculated with the use of safety margins. Exceeding the tolerable intake limit for a brief period does result in increased risk to health, as long as the average intake is below the tolerable intake over an extended time period.
Dioxin intake calculations, based on food consumption data from Riksmaten 2010 conducted by the National Food Agency, indicate that the average dioxin intake among adults is about 25% of the tolerable intake. Among children, the average intake is about 25-50% of the tolerable intake (Livsmedelsverket, 2011). Only a small number of children showed an intake in slight excess of the tolerable intake.
Herring and salmon represent a small part of total dioxin intake
The average intake of dioxins in the adult Swedish population as a whole is at present 3.5 pg/kg bodyweight/week (Livsmedelsverket, 2011). This can be compared to a reported average dioxin intake in Spain of 14 pg/kg bodyweight/week (2006), about 5 pg/kg body weight/week in the Netherlands (2004) and Belgium (2008), and 9 pg/kg/week in Finland (1998-2000) (Livsmedelsverket, 2011). The Scientific Committee on Food reported an average intake in Europe of 8-21 pg/kg bodyweight/week (SCF, 2001).
Overall, among Swedish adults the consumption of fish contributes on average to approximately 50% of the total dioxin intake (Livsmedelsverket, 2012). Consumption of Baltic Sea herring gives a contribution of about 12% (Livsmedelsverket, 2011). Other dietary sources to dioxins are meat, milk and dairy products, eggs and vegetable fat.
Lignell S, Aune M, Glynn A, Cantillana T, Fridén U. Levels of persistent halogenated organic pollutants (POP) in mother´s milk from first-time mothers in Uppsala, Sweden – results from 2008/2010 and temporal trends 1996-2010. Report to the Swedish EPA. http://www.slv.se/upload/dokument/risker/kemiska/Sakrapport_trend9610_121015.pdf
Livsmedelsverket (2011). Redovisning av uppdrag rörande gränsvärden för långlivade miljöföroreningar i fisk från Östersjöområdet. Rapport till Landbygdsdepartementet (in Swedish). http://www.slv.se/upload/dokument/remisser/regeringsuppdrag_2011/rapport_
Livsmedelsverket (2012) Market Basket 2010 – chemical analysis, exposure estimation and health-related assessment of nutrients and toxic compounds in Swedish food baskets. Report no. 7 – 2012. http://www.slv.se/upload/dokument/rapporter/kemiska/2012_livsmedelsverket_
Norén K and Meironyté D (2000) Certain organochlorine and organobromine contaminants in Swedish human milk in perspective of past 20-30 years. Chemosphere 40, 1111-1123.
SCF (Scientific Committee on Food) (2001) Opinion of the SCF on the risk assessment of dioxins and dioxin-like PCBs in food – update based on new scientific information available since the adoption of the SCF opinion of 22nd November 2000 (CS/CNTM/DIOXIN/20 REV 6 final)