NUMBER 05/09 October 2009
SURVEY OF FLUORINATED CHEMICALS IN FOOD
Retail samples of a variety of foods on sale in the UK were analysed for a range of fluorinated chemicals, including perfluorooctane sulphonate (PFOS) and perfluorooctanoic acid (PFOA). The results of this survey do not indicate any concern regarding human health from dietary exposure to these chemicals.
PFOS, PFOA and related fluorinated chemicals were analysed in individual retail samples of fish, offal, meat, eggs, milk, dairy products, bread, cereals, popcorn, vegetables and jams.
None of the chemicals was detected in almost three quarters of the samples, including all meat samples except offal.
PFOS was the chemical detected most frequently and usually at the highest concentrations, especially in fish, liver and kidney samples. The two highest concentrations of PFOS were in smoked eel and whitebait. PFOS was not detected in any samples of meat, potatoes, potato products, popcorn or other cereals, vegetable oils or fish oil dietary supplements.
Perfluorooctane sulphonamide (PFOSA) was the next most frequently detected chemical, but only in fish and shellfish. The highest concentrations were found in two whitebait samples.
PFOA was detected only in one sample of whitebait, six of crab and three of liver, all at low concentrations.
Using the results for foods included in this survey, the estimated average adult dietary intakes from the diet in 2007 were 0.01 microgram/kg bodyweight/day for PFOS and 0.01 microgram/kg bodyweight/day for PFOA (upper bound figures).
The corresponding high level adult dietary intakes were 0.02 and 0.02 microgram/kg bodyweight/day respectively. These are well below the Tolerable Daily Intakes (TDIs) recently set by the European Food Safety Authority of 0.15 and 1.5 microgram/kg bodyweight/day for PFOS and PFOA respectively.
The survey results do not raise any toxicological concerns.
PFOS belongs to a group of fluorinated chemicals often referred to as perfluoroalkyl substances (PFAS). Other chemicals in this group are homologues of PFOS and derivatives such as perfluorooctanesulphonyl fluoride (POSF), amines, amides, carboxylates and perfluorooctane sulphonamide (PFOSA). PFOA includes the anion and salts of perfluorooctanoic acid. PFOS salts are a component of fire-fighting foam concentrates and PFOA is primarily used as an emulsifier in industrial applications, for example in the production of fluoropolymers such as polytetrafluoroethylene (PTFE).
These chemicals have been imported into but not manufactured in the UK. They are very resistant to both chemical and biological degradation and are therefore persistent in the environment. Further information on the chemicals can be found in Food Survey Information Sheet No 11/06.1
Recently PFOS has been designated as a Persistent Organic Pollutant under the Stockholm Convention.2 This designation requires that usage must be phased out, but some uses are allowed to continue until suitable alternative products are available.
PFOS and PFOA tend to bind to certain proteins rather than to bioconcentrate in fat, but they have some potential to bioaccumulate in the food chain. Accordingly, they are more likely to be found in the blood and liver rather than the fatty components of foods. There have been relatively few reported occurrences of PFOS and even fewer of PFOA in food, although there have been some recent surveys, many of which have been of the blood and liver of fish.3-12 However, PFOS has also been detected occasionally in milk, ground beef,13-14 (3M, de Voogt, 2008) eggs,15 (Wang, 2008) and potato products16 and PFOA in eggs,15 (Yan, 2008) bread, apples and beans,13 potato products16 and in microwaveable popcorn bags.17 Cooking has little effect on the concentrations.18 Both chemicals have been detected in human milk.19-20 (So + Bernsmann, 2008). Other PFAS appear only to have been analysed in the liver of cattle, chicken and pigs in a Japanese study of farm animals in which PFOS and PFOA were also analysed.21 There is evidence that chemicals related to PFOS are accumulated into the food chain to a greater extent than chemicals related to PFOA.22 (Conder, 2008) Dietary intakes of PFOS and PFOA have been estimated in Germany by means of duplicate diet samples (Fromme, 2007),23 and in Canada by means of Total Diet samples (Tittlemeyer, 2007) and for the Inuit population, by retail foods.24,25
The Agency previously carried out a survey of the 2004 Total Diet Study (TDS) samples for fluorinated organic chemicals in food in the UK.1 The Total Diet Study is a model of the typical UK diet, and further information can be found in Food Survey Information Sheet No 38/03.26 None of the chemicals was detected in either the fish or offals food groups but several, including both PFOS and PFOA, were detected in the potatoes food group. PFOS was also detected in the eggs, sugar & preserves and canned vegetables food groups.1
This survey was carried out to:
investigate more fully which foodstuffs contain these chemicals,
enable previous estimates of dietary intakes of these chemicals by UK consumers to be improved
to provide data for use in any future EU negotiations
and in response to the suggestion from the scientific advisory Committee on Toxicity of Chemicals in Food, Consumer Products and the Environment (COT) that further data on the occurrence of these chemicals in food should be obtained.
The sampling plan for the survey was drawn up by Ventress Technical, who also purchased the samples.27 The plan covered a range of foodstuffs including fish, shellfish, meat, offal, eggs, milk, dairy products, potatoes and potato products, vegetables, vegetable oils, fish oil dietary supplements, bread, cereals, and popcorn. Sampling was weighted towards those types of food which were found in the 2004 TDS to contribute most to dietary intakes of the chemicals (potatoes and potato products) and those in which it was anticipated that the chemicals might be present on the basis of literature reports (fish, liver, potato products, popcorn) or their presence at low concentrations in the relevant TDS food group (potatoes, vegetables).
Samples were analysed by Food and Environment Research Agency (formerly the Central Science Laboratory (CSL)) using high pressure liquid chromatography-mass spectrometry following extraction and cleanup using the method of Taniyasu.28 Full details of the analytical methodology are about to be published29 and can be found in the contractor’s final report for the survey.30 The compounds measured are listed in Table 1. The inclusion of fluorinated chemicals other than PFOS and PFOA was limited by the availability of internal analytical standards.
For all types of sample the edible portions were analysed. In the case of fresh sprats and whitebait the whole fish were analysed, but for other species the head, bones, skin and gut were removed. Vegetables were washed and/or peeled according to normal culinary practice.
This report presents a summary of the upper bound results for PFOS and PFOA, and both the upper and lower bound results for the sum of all the PFAS analysed. (Tables 2a-2c). The concept of upper and lower bound is explained in Food Survey Information Sheet No 38/03.26 Full details of the results of each of the individual PFAS analysed can be found in Annex 1 and in the contractor’s final report for the work.30 Brand names are included in Annex 2.
In most of the samples none of the fluorinated chemicals was present at concentrations above the limit of quantification (LOQ – Limit of quantification, lowest content of the analyte which can be measured with reasonable statistical certainty).
PFOS was the most frequently detected chemical, and where detected it was usually the chemical present at the highest concentrations. PFOS was detected at the highest concentrations in oily fish samples, especially in one sample of smoked eel and two each of whitebait, and in crab, in liver samples, and at lower concentrations in white fish, some kidney samples and in one egg sample. In the majority of samples it was not found above the LOQ. PFOSA was detected in whitebait (which contained the highest concentration), sprats, sardines and crab. PFOA was detected only in one sample of whitebait, six of crab and three of liver, all at low concentrations. The other fluorinated chemicals measured were detected only occasionally (Table 1), but each chemical was detected in at least one food sample. Six fluorinated compounds were detected in one of the crab samples and five in one of the whitebait samples, in both cases including PFOS, PFOA and PFOSA. None of the chemicals was detected in any of the samples of either farmed or wild salmon.
Dietary intakes of PFOS, PFOA and PFOSA were estimated by applying average concentrations of the chemicals found in the oily fish, white fish, shellfish, liver, kidney, meat, milk and milk products, cereals, popcorn, jams, potatoes and vegetables samples to all samples of the relevant food type. These dietary intake estimates do not take account of the food types that were not included in the survey and cannot therefore be described as ‘total’ dietary intakes. However, the dietary staples (bread, milk and potatoes) and food groups that were anticipated to make the highest contributions to dietary intakes (fish and offal) as well as meat and vegetables were included. Tables 3a and 3b show the dietary intakes (upper and lower bound) of PFOS and PFOA by consumers of various age groups, estimated using food consumption data from various dietary surveys.31-34
The estimated upper bound average dietary intakes of fluorinated chemicals (Tables 3a and 3b) by adults from the diet in 2007 were 0.01 microgram/kg bodyweight per day for PFOS and 0.01 microgram/kg bodyweight per day for PFOA. The corresponding estimated high level (97.5 percentile) intakes were 0.02 and 0.02 microgram/kg bodyweight per day. The concepts of average and high level dietary intakes, are explained in Food Survey Information Sheet No 38.26 Despite the concentrations of PFOS being higher in fish and offal than those of PFOA, the intakes round to the same values due to the relatively low consumption of these food types by most age groups. Dietary intakes have also been estimated specifically for consumers eating portions of smoked eel, whitebait and crab with the highest concentrations of PFOS found in the survey and portions of sprats, whitebait and crab with the highest concentrations of PFOSA (Tables 4 and 5).
The LOQs in this survey were mostly lower than the limit of determination (LOD – The lowest concentration of a chemical that is measurable with confidence by the analytical method used) achieved in the 2004 TDS survey. The current LOQ is lower than the previous LOD as a result of improvements to the analytical methodology. The higher value probably explains why PFOS was not detected in the offals food group in the 2004 TDS.1 Because the quantities and relative proportions of foods making up the TDS are largely based on consumption data, the 2004 TDS fish group contained a higher proportion of white than oily fish. In addition, it did not contain any carp, whitebait or eels (the species with the highest concentrations found in the current survey) because consumption of these species is relatively low. This may also explain to some extent the chemicals were not detected in the fish food group. The results show that PFOS was detected mainly in the fish and offal samples, which is in line with findings in other countries. However the chemicals were not detected in any potato or potato product samples in contrast to the detection of several chemicals in the potatoes TDS food group in the earlier survey1 and in the literature.16 The reason for this difference is unclear and cannot be determined from this work.
The estimated dietary intakes of PFOA from the diet in 2007 are well within the TDI of 1.5 microgram/kg bodyweight set by the COT35 and EFSA.36 Similarly, the estimated intakes of PFOS are well below ther TDIs of 0.3 and 0.15 microgram/kg bodyweight respectively established by the COT37 and EFSA.36 Although there are very few toxicological data on the chemicals other than PFOS and PFOA the very low concentrations found and the small number of foods in which they were detected result in estimated dietary intakes that are below thresholds of concern.38 The intakes of PFOS and PFOA are also well within the TDIs when consuming four weekly portions (the maximum rate of oily fish consumption advised by the Agency)39,40 of the oily fish with the highest concentrations of PFOS (smoked eel and whitebait) in combination with the rest of the diet. Since most oily fish contained much lower concentrations of PFOS and PFOA than whitebait and eel, it is unlikely that even high level consumers of oily fish would exceed the TDI.
The COT noted the results of the 2004 TDS survey and considered that there was considerable uncertainty in intakes, since the majority of food groups did not contain PFOS or PFOA at concentrations above LOQs.35,37 The new survey results help to reduce the uncertainty in the intake assessment and do not raise any toxicological concerns.
Summary of Units
kg a kilogram (kg) is one thousand grams (g)
microgram one millionth of a gram
microgram/kg bw/day nanograms per kilogram of bodyweight per day; equivalent to parts per million million (parts per trillion) by weight.
READ THE FULL 56 PAGE REPORT AT http://www.fluoridealert.org/re/pfoa-pfos.uk.survey.2009.pdf
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