Food Standards Agency UK - Survey of Ethyl Carbame in Whisky (Number 02/00)

• Ethyl carbamate is naturally produced during food processing, particularly in some distilled spirit drinks and fermented foods, such as whisky, fruit brandies, beer, wine, bread and yoghurt.
• In 1992, expert committees recommended that ethyl carbamate in foods should be reduced to the lowest possible levels and supported the need for a further survey after an appropriate period.
• 205 whisky samples were analysed in the survey. The samples included blended and single malt Scotch whiskies and imported whiskies. The highest levels were found in 10 year old malt whiskies produced before new measures were introduced by the industry. The analytical results of 64 additional samples of younger stocks of these whiskies were all much closer to the average concentration of ethyl carbamate found in the whole survey.
• This survey showed that mean levels of ethyl carbamate in whisky were considerably lower than found in previous surveys. The measures taken to reduce the levels were clearly effective.

A comprehensive survey to measure ethyl carbamate in whisky has been completed. 205 samples of whisky were analysed for ethyl carbamate by the Scotch Whisky Research Institute (SWRI). The survey included blended and single malt Scotch whiskies and imported whiskies. The mean level was 29 microgram/l, which was significantly lower than in previous surveys.

Three samples of 10 year old single malt Scotch whiskies produced before industry's action in the early 1990s contained higher levels of ethyl carbamate. The analysis of 64 additional samples of maturing stock of whiskies, produced between 1989 - 1999, contained levels which were much closer to the average level of the other samples, showing that the distillers had successfully taken action to reduce levels of ethyl carbamate.

Ethyl carbamate is a chemical formed naturally during fermentation of food and beverages. It has been shown to be a genotoxic carcinogen in animals and is considered to be a potential carcinogen in humans.¹ When consumed in food or drink, most ethyl carbamate is degraded in the body within 24 hours, to carbon dioxide, water and ammonia, with the intermediate formation of ethanol and other metabolites. The majority of the remainder is excreted in urine as unchanged ethyl carbamate.

Concern first arose in 1985 when a survey of alcoholic beverages sold in Canada found elevated levels of ethyl carbamate in certain alcoholic beverages. As a result the Canadian Health Protection Board introduced a guideline limit of 150 microgram/l for ethyl carbamate in distilled drinks.² There is no similar guideline limit in the UK.

Earlier studies in 1990 - 92³ by the Ministry of Agriculture, Fisheries and Food had analysed spirit drinks, fruit brandies, beer, wine, bread and yoghurt for ethyl carbamate. Using data from these studies and data on consumption of these products, it was possible to calculate which products were the major sources of dietary exposure to ethyl carbamate. The largest mean intakes arose from whisky.³

In 1992, the Committee on Toxicity of Chemicals in Food, Consumer Products and the Environment (COT) considered ethyl carbamate as part of its review of certain naturally occurring toxicants. The Committee recommended that the levels of ethyl carbamate in various items of the diet should be reduced to the lowest technologically achievable. The Food Advisory Committee (FAC) endorsed the COT's recommendations and supported the need for a further survey after an appropriate period of time.

Research on whisky has shown that ethyl carbamate is formed during distillation and using the right barley varieties and distillation conditions are the key control parameters.⁴ As a result, since the early 1990¿s the Scotch whisky industry has taken steps to reduce the level of ethyl carbamate in whiskies by selecting barley varieties with naturally low levels of precursors of ethyl carbamate. Studies have also shown that copper catalyses the formation of ethyl carbamate during the traditional double distillation procedure used in the manufacture of Scotch whisky. If copper contact can be maximised early on in the distillation to promote ethyl carbamate formation from its precursor, the non-volatile ethyl carbamate is not distilled over into the spirit. The industry has gone to considerable length to ensure that the spirit is in contact with copper for as long as possible. For example, distillation of grain spirit is typically carried out in the presence of sacrificial copper. Likewise, a third distillation, as occurs in the production of Irish whiskey, will also help ensure that ethyl carbamate levels are low.

The youngest whisky used during bottling defines the declared age of a whisky. For a blended whisky, this is typically 3 years, but most single malts contain whiskies that are 10 years old or more. Hence, for single malts, it was recognised that some spirit laid down before industry took action was still being bottled and thus likely to be included in the survey.

The objective of this survey was to measure ethyl carbamate concentrations in whisky and to assess the effectiveness of industry's action to reduce levels of this toxicant.

The Scotch Whisky Research Institute (SWRI) was contracted through competitive tender to carry out the analysis. SWRI is an industry-funded institute and, to avoid any suggestion of a possible conflict of interest, an independent laboratory was commissioned to purchase and sub-sample the whiskies. The samples were dispatched to SWRI in identical bottles, sealed in individual bags to ensure sample integrity, with only unique numbers for identification. The SWRI did not know, at the time of analysis, the identity of the samples.

In line with current procedures, the survey was designed to be representative and reflect share in the UK market of blended and single malt Scotch whiskies and imported whiskies. Samples were purchased from 10 geographical locations throughout the UK at a range of retail outlets, taking care to avoid the replication of batch codes on multiple brand purchases.

The samples were analysed using a UKAS accredited method. Whisky samples were adjusted to 70 per cent v/v alcohol strength with an appropriate methanol solution and were analysed directly by Gas Chromatography - Mass Spectrometry (GC-MS) with selected ion monitoring, m/z 62. An internal standard (n-propyl carbamate) was added to the calibration standards, test samples and three quality control samples. The limit of detection was 5 microgram/l, the limit of quantification 10 microgram/l and the measurement of uncertainty 5 microgram/l.

In keeping with the standard method, confirmation and analysis of a further sub-sample was carried out on samples with observed levels of greater than 100 microgram/l, allowing for the measurement of uncertainty. Samples were qualified using ion m/z 74, and the presence of ethyl carbamate confirmed where the relative ratios of ion m/z 62 to m/z 74 lay within acceptable limits.

A mean concentration of 29 microgram/l of ethyl carbamate was found in the 205 samples analysed, with values ranging from not detectable to 239 microgram/l. The data are summarised in Table 1 and Figures 1 & 4. Full results for all samples, including brand names, are at Appendix 1.

Figure 1 shows the distribution of ethyl carbamate contamination found in the whisky samples. The majority of samples 114 (56 per cent) contained ethyl carbamate in the range 11-30 microgram/l. Four samples contained ethyl carbamate above 110 microgram/l. Figure 2 shows the distribution of ethyl carbamate concentrations in the blended whisky samples. Of the 107 samples analysed, 53 (50 per cent) were in the range 11-20 microgram/l. The highest concentration of ethyl carbamate found in a blended whisky sample was 82 microgram/l. Figure 3 shows the range of concentrations for imported whisky samples. 11 (34 per cent) were in the range 11-20 microgram/l and 12 (38 per cent) in the range 21-30 microgram/l. One sample of imported whisky contained a high concentration of ethyl carbamate of 104 microgram/l. Figure 4 shows the range for single malt samples, with the majority 23 (35 per cent) in the range 31-40 microgram/l and with 4 (6 per cent) containing levels greater than 100 microgram/l.

Comparison of the data on Scotch whisky with the findings of the previous surveys has been made in Table 2. The ability to make comparisons between the surveys is limited because of the smaller sample numbers and the different sampling plans in the earlier surveys. Nevertheless, the mean level of ethyl carbamate in whisky has decreased substantially since the earlier surveys (present mean of 30 microgram/l compared with the previous mean range of 45 - 54 microgram/l).

A small number of samples from the present survey were found to have elevated levels of ethyl carbamate. Given the comprehensive nature of the survey and the age of some of the whiskies, it was not surprising that a small number were produced before industry took action to reduce concentrations. The three samples with elevated concentrations were all single malt whiskies with a declared age of 10 years and of two different brand names. As a result, a distillery contracted SWRI to analyse 64 randomly selected samples with a minimum of five from each year of maturing whisky stocks that had been laid down between 1988 and 1999.

The results are given in Appendix 2 and Figure 5. The results show that from an initial mean level of ethyl carbamate of 121 microgram/l in spirit laid down in 1988, levels in subsequent years declined markedly to a mean level of 27 microgram/l in 1999. The overall mean level of ethyl carbamate in spirit laid down in the years 1989 - 1999 was 34 microgram/l. Discussions further revealed that the samples analysed as part of the main survey were solely from spirit laid down in February 1988.

Following the advice and recommendations of the COT and FAC in 1992, industry took action to reduce the levels of ethyl carbamate in whisky. The timing of this survey reflects the delay required before any improvement could have been realistically expected due to the lengthy maturation process for whisky production. A large majority (83.4 per cent) of the whiskies contained concentrations of ethyl carbamate in the range 10 - 40 microgram/l. Of the three elevated results all were single malts with a declared age of 10 years indicating that distillation had occurred before the industry had completed its action. This was confirmed with low analytical results from 64 additional samples of younger stocks of maturing whiskies.

It is only possible to make a limited comparison of data from this and previous surveys as considerably fewer samples were analysed in 1990 - 92. The higher values reported in this survey are due to the more comprehensive nature of the survey. Nevertheless, the mean level of 30 microgram/l for Scotch whiskies found in this survey is significantly lower than the mean values of 45 - 54 microgram/l from the previous studies and this clearly shows an impact of action taken by industry.

In preparing this data, this survey was considered by the FAC, which agreed the following statement.
"The Committee welcomed the decline in ethyl carbamate concentrations in whisky shown by this survey since the earlier surveys in 1990 - 92 and was reassured by the additional data on more recent production. The Committee recommended that the situation should be monitored in the future after an appropriate interval."

It should be noted that although ethyl carbamate is a potential carcinogen to humans, low levels are thought not to pose a risk to human health. In 1987 the COT considered data on the toxicity of ethyl carbamate and concluded that; "The levels and intakes of ethyl carbamate in the UK diet are generally low, any risks to health resulting from these intakes are small, and are likely to be much less than the known risks of consuming alcoholic beverages."

The levels of ethyl carbamate found in whisky in this survey were substantially lower than those observed previously. Samples which were shown to have higher concentrations of ethyl carbamate were from older stock and additional analyses of younger stock showed that levels had fallen in more recent production. This reflects the successful action taken by industry to reduce the levels of ethyl carbamate in whisky. It is, however, recognised that further reduction will become more difficult.

The FAC considered all these data and was reassured that the advice and recommendations had been acted upon. It welcomed the significant decrease in the levels of ethyl carbamate in whiskies as a result of action by the industry. A further survey of ethyl carbamate in whisky is planned after an appropriate time to check that levels have not risen.

Summary of Units

Microgram: one millionth of a gram
Litre (l): one thousand millilitres
Micrograms per litre
v/v: volume/volume
m/z: mass/charge

1. Zimmerli. B and Schlatter. J, (1991) Ethyl Carbamate: analytical methodology, occurrence, formation, biological activity and risk assessment. Mutation Research. 259, 325-350.
2. Dennis. M. J, Howarth. N, Key. P.E, Pointer. M and Massey. R.C, (1989) Investigation of ethyl carbamate levels in some fermented foods and alcoholic beverages. Food Additives and Contaminants. 6 (3), 383-389.
3. Ministry of Agriculture Fisheries and Food (1994) Naturally Occurring Toxicants in Food. Food Surveillance Paper 42, 32-38.
4. Riffkin, H. L., R. Wilson, et al. (1989). "Ethyl Carbamate Formation in the Production of Pot Still Whisky. Journal of the Institute of Brewing. 95, 115-9.

For further information please contact:
Mrs Sue Johns
Food Standards Agency
Contaminants Division
PO Box 31037
Room 210, Ergon House
17 Smith Square
London SW1P 3WG
Tel: + 44 (0) 20 7238 6772
Fax: + 44 (0) 20 7238 5331

Email: sue.johns@foodstandards.gsi.gov.uk

A full copy of the report of this survey has been placed in the MAFF Library, Nobel House, London, SW1P 3JR, Tel: +44 (0) 20 7238 6575. If you wish to consult a copy please contact the library for an appointment giving at least 24 hours notice. Alternatively photocopies can be obtained from the library; a charge will be made for photocopying and postage.

Further copies of this Information Sheet can be obtained from:
Food Standards Agency Information Centre
PO Box 31037
Room 303b, Ergon House
17 Smith Square
London SW1P 3WG
Tel: + 44 (0) 20 7238 6223
Fax: + 44 (0) 20 7238 6330
Email:information.centre@foodstandards.gsi.gov.uk

Copies of Committee on Toxicity of Chemicals in Food, Consumer Products and the Environment (COT) statements can be obtained from:
Mr Jonathan Lighthill
COT Secretariat
PO Box 30077
Room 651C, Skipton House
80 London Road
London SE1 6XZ

Tel: + 44 (0) 20 7972 5007
Fax: + 44 (0) 20 7972 5134
Email: jonathan.lighthill@foodstandards.gsi.gov.uk

Further information on the work of the Food Advisory Committee (FAC) can be obtained from:

Mr John Caseley
FAC Secretariat
PO Box 31037
Room 224, Ergon House
17 Smith Square
London SW1P 3WG

Tel: + 44 (0) 20 7238 6267
Fax: + 44 (0) 20 7238 6263
Email: john.caseley@foodstandards.gsi.gov.uk