Survey of 1,3-Dichloropropanol (1,3-DCP) in Soy Sauce and Related Products (Number 15/01)

Tuesday 19 June 2001

Food Survey Information Sheet

Key Facts

• 1,3-Dichloropropanol (1,3-DCP) belongs to a group of chemical contaminants known as chloropropanols.
• 1,3-DCP is known to cause cancer in animals by directly damaging genetic material. Experts committees have recently reconsidered their opinion and confirmed that it is prudent to assume that this may also occur in humans.
• There are currently no limits for 1,3-DCP, but expert advice is that they should be present in foods at the lowest technologically feasible level, which for soy sauce equates to not present.
• 17 per cent of the 100 samples of soy sauce and related products analysed in this survey contained quantifiable levels of 1,3-DCP.
• Consumers are advised to avoid products identified in this survey as containing 1,3-DCP.
• The Agency is working with Local Authorities to ensure that products identified in this survey as containing 1,3-DCP are no longer on sale in the UK.
• The Agency will shortly commission further surveys of chloropropanols in soy sauces, in both retail and catering outlets, and a survey of 1,3-DCP in foods as soon as possible.

Summary
A survey of 1,3-DCP in a range of soy sauces and related products available in the UK has recently been completed. 100 samples of soy sauce and related products were purchased by Ventress Technical Ltd. from retail outlets in the UK. The analysis of the samples was conducted by the Central Science Laboratory (CSL) using an in-house validated method of analysis with a limit of quantification of 0.005 mg/kg for 1,3-DCP. 1,3-DCP was quantified in 17 per cent of samples. All samples with quantifiable levels of 1,3-DCP were found to contain levels of 3-monochloropropane-1,2diol (3-MCPD) above the proposed EU limit 0.02 mg/kg for 3-MCPD in soy sauce and HVP based on a 40% dry matter content.

Background
1,3-DCP is one of a group of chemical contaminants known as chloropropanols. 1,3-DCP, together with 3-MCPD, was originally identified as a contaminant of the savoury ingredient acid-hydrolysed vegetable protein (acid-HVP),1 which is produced by treating proteins from hydrolysed vegetables, such as soya, with hydrochloric acid. In acid-HVP, components of fats and oils in the starting materials are chlorinated at high temperature to form chloropropanols.

In 1988 the EC Scientific Committee on Foods (SCF) considered chloropropanols and 1,3-DCP in particular; after considering available data, it agreed that 1,3-DCP is a genotoxic carcinogen, that is it causes cancer by directly damaging genetic material. The Committee on Carcinogenicity of Chemicals in Food, Consumer Products and the Environment (COC) first considered 1,3-DCP in 1991. They concluded that it would be prudent to regard it as a genotoxic carcinogen in-vivo. Following this assessment, the FAO/WHO Joint Expert Committee on Food Additives (JECFA) concluded in 1993 that, because of its carcinogenicity, 1,3-DCP is an undesirable contaminant in food and that levels should be reduced to as low as technologically achievable.2 The Committee on Mutagenicity of Chemicals in Food, Consumer Products and the Environment (COM) and COC both recently considered 1,3-DCP and concluded:

COM statement3:"The committee concluded that it would be prudent to regard 1,3-DCP and 2,3-DCP as potentially genotoxic in-vivo and agreed that both compounds should be tested for genotoxicity in-vivo using the approach set out in the COM guidelines."
COC statement4: "It is prudent to assume that 1,3 DCP is a genotoxic carcinogen and that exposure to 1,3 DCP should be reduced to as low a level as technologically feasible."
1,3-DCP is formed from its precursor 3-MCPD and has been shown to occur in soy sauces.5 However, no clear relationship exits between the relative concentration of 1,3-DCP and 3-MCPD in a product except that the concentration of 3-MCPD is significantly higher than 1,3-DCP. In light of this information and the anticipated advice from the COM and COC, the samples collected for the further survey of 3-MCPD in soy sauces and related products, commissioned in 2000, were also analysed for 1,3-DCP. These data are being reported concurrently in Food Survey Information Sheet 14/01.

In line with the guidelines for planning, conducting and reporting surveys,6 manufacturers whose products were found to contain quantifiable levels of 1,3-DCP (i.e. above 0.005mg/kg) were sent details of their individual results. They were invited to submit comments of up to 200 words. These are reported in Annex 1.

Sampling
100 samples of soy sauces and related products were purchased from retail outlets in four areas of the UK; London, Leeds, Manchester and Cambridge during August 2000. Of these samples 67 were soy sauces, the remaining samples were various other related sauces i.e. mushroom soy, oyster and teriyaki. The details of each sample were recorded on receipt and descriptions are reported in Table 1. The absence of a particular brand from this table means only that the product was not included in the survey. 34 of the products sampled had been analysed in the 1999 survey for 3-MCPD. The remaining samples were selected at random to reflect the wide range of products and included own brands as well as proprietary brands.

Methodology
1,3-DCP was measured by an automated headspace procedure with gas chromatographic separation and mass spectrometric detection. The method, which incorporated a deuterium labelled internal standard, had previously been validated in-house and shown to have a limit of quantification of 0.005 mg/kg. Quantification was based on a calibration series of 1,3-DCP standard solutions, equivalent to a range of concentrations 0.003 to 1.3 mg/kg 1,3-DCP, measured with each batch. Recovery is incorporated in the method.

Analytical results have a variability known as the measurement uncertainty (details are given in Annex 2). For any analytical method each result reported is the best estimate for that sample, it is always qualified by the measurement uncertainty, e.g. x mg/kg ¿ y mg/kg. The analytical data showed that the analyses met the quality assurance criteria set (details are given in Annex 3).

Results
A full list of results, including details of the brand names for each product is given in Table 1. 17 out of 100 samples (17 per cent) contained quantifiable levels of 1,3-DCP, all of which contained levels of 3-MCPD greater than 0.02 mg/kg and also greater than the level of 1,3-DCP observed. The highest level of 1,3-DCP was 0.345 mg/kg, in a soy sauce.

Interpretation
Quantifiable levels of 1,3-DCP were only found in samples that had levels of 3-MCPD above 0.02 mg/kg. This was not unexpected, as 3-MCPD has been shown to be a precursor of 1,3-DCP.7 The results of this survey also indicate that when 3-MCPD and 1,3-DCP are found, the amount of 3-MCPD is always significantly higher. However, no direct correlation was observed between the levels of 3-MCPD and 1,3-DCP.

Expert committees have advised that it is prudent to consider that 1,3-DCP is a genotoxic carcinogen, and it should therefore be reduced to the lowest technologically feasible level in foods. It is possible to eliminate the chloropropanols from soy sauces and related products, as shown by the results of this survey and from published literature on the origin of chloropropanols in soy sauce. Hence, 1,3-DCP need not and should not be present in soy sauce and related products.

Possible sources of chloropropanols in soy sauces are:

• The addition of acid-HVP,
• Acid hydrolysis of some or all of the soya bean/wheat and
• The toasting of the wheat component.

However, it is not possible to explore any link between method of manufacture and level of chloropropanols, without further verifiable information from the producers.

Conclusion
This is the first survey of 1,3-DCP in soy sauce that has been reported by the Agency. Quantifiable levels of 1,3-DCP were found in 17 per cent of samples analysed and all those samples also contained levels of 3-MCPD greater than the proposed EU limit. The results show that sauces with unacceptable levels of 1,3-DCP are available in the UK. It is possible to eliminate 1,3-DCP from soy sauces and related products therefore any quantifiable amount is unacceptable. Those retailers responsible for selling soy sauces identified as containing quantifiable levels of 1,3-DCP and 3-MCPD above the proposed EU limit, were asked to remove any remaining stock from the shelves.

The Agency is working with the Local Authorities Co-ordinating Body on Food & Trading Standards (LACOTS) to take this forward as set out in Information Sheet 14/01 with enforcement officers visiting retailers whose products were shown to have high levels. This course of action supplements our dialogue with UK distributors of these products. Consumers are advised to avoid products identified in this survey as containing 1,3-DCP.

The Agency will conduct further surveys of soy sauces shortly to assess the progress made by industry in reducing levels of chloropropanols in soy sauce and related products in both retail and catering establishments. Those products found to have unacceptable levels of 1,3-DCP in this survey will be targeted in the follow up survey. The Agency also intends to commission a survey of 1,3-DCP in selected foods as soon as possible.

Summary of Units
Milligram (mg): one thousandth of a gram
Kilogram (kg): one thousand grams
Milligrams per kilogram (mg/kg)

References

1. Velisek, J. D., Davidek, J., Kubelka, V., Janicek, G., Svobodova, Z and Simicova, Z. New Chlorine Containing Organic Compounds in Protein Hydrolysates. Journal of Agricultural and Food Chemistry, 1980, 28, 1142-44.
2. Olsen P. (1993) Chloropropanols In: Toxicological Evaluation of Certain Food Additives and Contaminants, Joint Expert Committee on Food Additives, World Health Organization, Geneva, Switzerland, (41st Meeting). [WHO FOOD ADDITIVES SERIES: 32] 267-285.
3. Mutagenicity of 1,3-Dichloropropan-2-ol (1,3-DCP) and 2,3-Dichloropropan-1-ol (2,3-DCP) Statement - COM/01/S2 - May 2001. http://www.advisorybodies.doh.gov.uk/com/statements.htm
4. Carcinogenicity of 1,3-Dichloropropan-2-ol (1,3 DCP) and 2,3-Dichloropropan-1-ol (2,3 DCP)Statement - COC/01/S1 - January 2001. http://www.advisorybodies.doh.gov.uk/coc/cocdcp.htm
5. 5 Crews C., Le Brun G., Hough P., Harvey D. and Brereton P. Chlorinated propanols and levulinic acid in soy sauces. Czech Journal of Food Sciences, 18, 276-277, 2000.
6. Velisek J., Davidek J.,Hajslova J., Kubelka V., Janicek G., Mankova B. Z.Lebensmit.-Untersuch. Forsch., 167, 241-244, 1978.

Further Information
Further information on this survey can be obtained from:
Mrs Sue Johns Contaminants Division Room 707c, Aviation House 125 Kingsway London WC2B 6NH
Tel: +44 (0) 20 7276 8712 Fax number: 020 7276 8717 Email: sue.johns@foodstandards.gsi.gov.uk

The full report of this survey is held in the Elsie Widdowson Library at Aviation House, 125 Kingsway, London WC2B 6NH Tel: +44 (0) 20 7276 8181. If you would like to consult a copy, please contact the Library giving at least 24 hours notice or, alternatively, copies can be obtained from the Library; a charge will be made to cover photocopying and postage. Further copies of this Information Sheet can be obtained from: Library and Information Service Food Standards Agency Room 115B, Aviation House 125 Kingsway London WC2B 6NH Tel: +44 (0) 207 276 8187 Email: library&info@foodstandards.gsi.gov.uk

Copies of the statements from the Committee on Mutagenicity of Chemicals in Food, Consumer Products and the Environment and the Committee on Carcinogenicity of Chemicals in Food, Consumer Products and the Environment the can be obtained from: Khandu Mistry Room 692D, Skipton House 80 London Road London SE1 6LH Tel: +44 (0) 20 7972 5020 Fax: +44 (0) 20 7972 5156 Email: Khandu.Mistry@doh.gsi.gov.uk

Annex 1 - COMMENTS
From Lee Kum Kee

As a manufacturer of high quality products, Lee Kum Kee is in full compliance with regulatory standards worldwide.

Lee Kum Kee takes its responsibilities to its consumers around the world very seriously. In fact, the company introduced new operating procedures following the FSA report in 1999 to ensure the highest quality of products - meeting or exceeding local regulatory standards. These procedures included changes in sourcing raw materials, changes in product formulations, and stringent testing at all stages of ingredient selection and production.

Consumers can be assured that Lee Kum Kee has eliminated any traceable levels of the reported substances, including 3-MCPD, 1,3-dichloropropan-2-ol (1,3-DCP) and 2,3-DCP in those products produced by the company after October 1999. Samples identified in the FSA reports were all products manufactured by Lee Kum Kee prior to those operating procedures introduced by the company in 1999.

Lee Kum Kee is, in fact, the only Hong Kong food company with its own laboratory that has received Hong Kong Laboratory Accreditation Service's international accreditation for testing against 3-MCPD in raw materials and finished products. In addition, Lee Kum Kee continues to work closely with internationally accredited laboratories as part of its quality assurance measures.

From JK Foods (UK)
Sample No. 60036
Tung Chun Thick Soy Sauce 250ml
We have withdrawn current stock from sale and initiated a recall for stock that has been sold within the last six months. We will put this product on hold until our supplier in Hong Kong can revise the formula to eliminate 1,3-DCP.

Sample No. 60062
Golden Mountain Soya Bean Sauce 200ml
This product is a discontinued line, the last imported consignment was received on 12th July 2000 and sold by 7th September 2000.

Sample No. 60076
Pearl River Bridge Superior Soy 150ml
We no longer import this product. The sole importer is: SW Trading.

Annex 2 - MEASUREMENT UNCERTAINTY
1,3-DCP
The measurement uncertainty was calculated from between-batch precision and mean recoveries for soy sauces containing about 0.005, 0.1 and 1 mg/kg 1,3-DCP and a sauce without detectable 1,3-DCP which had been fortified with 1,3-DCP at these levels. These were considered to be representative of levels in the survey samples. The measurement uncertainty samples were analysed in eight separate batches over a period of three weeks. The samples were analysed in batches. Each batch included a reagent blank, and reference soy sauces containing approximately 0.005 and 0.1 mg/kg 1,3-DCP.

Measurement uncertainty for 1,3-DCP was assessed to be ±0.002 mg/kg at a level of 0.005 mg/kg 1,3-DCP, ±0.085 mg/kg at a level of 0.1 mg/kg 1,3-DCP and ±0.27 at a level of 1 mg/kg 1,3-DCP.

Annex 3 - ANALYTICAL QUALITY ASSURANCE
1,3-DCP
Formal quality criteria were not set for 1,3-DCP as the method has not yet been fully validated and reference materials have not been fully characterised. However batches in which the reagent blank contained detectable 1,3-DCP were to be repeated, and samples containing in excess of the calibration range were to be diluted.

Results

• In each batch the reagent blank contained less than the equivalent of 0.003 mg/kg 1,3-DCP.
• No samples contained 1,3-DCP in excess of the calibration range.
• The linearity of the calibration graphs for each batch exceeded 0.99.
• The standard deviation of the results for the reference sauce containing 0.005 mg/kg was 0.0007 and for the reference sauce containing 0.1 mg/kg was 0.0138