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Processing
"An update on 3 MCPD issues"
September 19, 2011
One of the processing sessions of the conference, chaired by Gerhard de Ruiter (Sime Darby, The Netherlands) was composed to give an update on issues with regard to 3-monochloropropane-1,2-diol (3- MCPD) esters and 2,3-epoxy-1-propanol esters (glycidyl) esters. 3- MCPD and glycidyl esters have recently been found in refined fats and oils. Although no evidence is available indicating any adverse health effects caused by the consumption of these substances, they have raised safety concerns due to being potential indirect sources of free 3-MCPD and glycidol.
This session started by a key note lecture given by Professor Yvonne Rietjens of the Wageningen University: "Is there a need for Concern?" The presentation provided an overview of the current status of the safety assessment of 3-MCPD esters and glycidyl esters. Rietjens presented her work to come to a toxicological risk assessment of 3-MCPD-and glycidol esters. Several safety evaluations concluded that there are no data available about the toxicological effects of 3-MCPD-and glycidyl esters. Therefore risk assessment is generally based on toxicological data on free 3-MCPD or glycidol, under the assumption that upon intake 100% of 3-MCPD or glycidol are released from their esters. She explained that 3-MCPD is a non-genotoxic carcinogen and a Tolerable Daily Intake (TDI) of 2 µg/kg body weight per day was established by the Scientific Committee on Food (SCF) and the Joint FAO/WHO Expert Committee on Food Additives (JECFA). Both SCF and JECFA used an uncertainty factor of 500 to account for three aspects: i) the default uncertainty factor of 100 for intra-and interspecies differences, ii) the fact that the TDI was derived from a Lowest Observed Adverse Effect Level (LOAEL) and not a NOAEL (No Observed Adverse Effect Level) for renal tubular hyperplasia, and iii) other limitations in the database (e.g. lack of reproduction/developmental toxicity studies). However, she showed in her presentation that, when using another approach to establish the TDI, the so called BenchMark Dose (BMD) methodology with a BMDL10 value as point of departure instead of the LOAEL, part of this uncertainty factor of 500 would no longer be needed. This BMD approach derives a TDI-range for 3-MCPD of 6,6-8,7 µg/kg body weight per day, which is much higher than the TDL as established by SCF and JECFA. This TDI is no longer below the estimated current worst case intake levels of 3-MCPD, indicating that there is no need for concern. Furthermore, she presented the latest study from EFSA of 3-MCPD measurements in rats, which were published last month. These very essential new data gave new insight in the amount of hydrolysis of 3-MCPD esters. When using these new data in calculating the risk assessment, this could result in even a higher TDI. She ended her presentation by also shortly focussing on the risk assessment of glycidol. Glycidol is judged to be a genotoxic carcinogen and its risk assessment can be based on estimating a Margin of Exposure (MOE) using the BMDL10 value derived from the National Toxicology Program (NTP) carcinogenicity study on glycidol. Her conclusion was that, with regard to glycidol, based on this approach, it emerges that for most groups within the population, except for babies fed infant formula, there would be only a low level of concern.
The second presentation of this session on 3-MCPD issues was given by Kornél Nagy (Nestlé Research Center in Lausanne, Switzerland). He presented the newest insights in the mechanisms of the formation of MCPD- and Glycidyl-ester in edible oils. He showed that, thanks to techniques based on isotope dilution combined with liquid chromatography-mass spectrometry and thanks to the recent introduction of novel mass spectrometric approaches such as ultrahigh resolution based mass defect filtering, the holistic mapping of chlorinated compounds is feasible. These new analytical opportunities enable the discovery of chlorine sources potentially responsible for the generation of 3-MCPD-esters and open new ways to understand their formation mechanisms.
The third presentation of this session came from Karel Hrncirik (Unilever R&D in Vlaardingen). The large variation in the levels of 3-MCPD/glycidyl esters observed amongst oils of different origin (and even within the oils of the same origin) suggests that they are dependent on minor intrinsic compositional changes of oils and/or different processing conditions. In his speech, Hrncirik gave an overview of factors affecting the formation of 3-MCPD/glycidyl esters during edible oil refining, covering both refining conditions and compositional variation of the crude oils, and relevant possibilities to develop the most effective mitigation strategy. He concluded that, also due to the fact that the chlorine source responsible for the formation of 3-MCPD esters remains unknown, an outcome of the effort to reduce the precursors of 3-MCPD esters in raw material, for example by changing cultivation conditions or minimizing enzymic hydrolysis of triglycerides, is uncertain and the attention should focus more on refining. While reviewing the entire refining process, Hrncirik showed that the formation of 3-MCPD and glycidyl esters occurs mainly during the deodorisation step, typically at temperatures above 180 ºC and 230 ºC, respectively. Several pathways of heat-induced formation of 3-MCPD/glycidyl esters have previously been proposed, but the reaction mechanisms still remain to be completely elucidated. He demonstrated that the type and amount of bleaching earth plays a role, since acidity (and possibly chloride content) of bleaching earth may have an impact on the formation of 3-MCPD esters, although, there is a risk that altered conditions of bleaching may negatively impact the quality of the final product. With regard to post-refining, his experimental data showed that interesterification, introduced as an additional post-treatment, is an efficient step to reduce the level of 3-MCPD esters. But he stressed again that the quality of the final product must be taken into account, since physical properties of treated oil/fat might be changed significantly by this process.
Bertrand Matthäus from the Max Rubner-Institute in Germany presented the results from the German FEI Research Project concerning 3-MCPD esters and related compounds. The definition of mitigation strategies for 3-MCPD-esters and related compounds was the aim of one part of a research project (initiated by the German food industry with financial support of the Research Association of the German Food Industry (FEI) and the German Federal Ministry of Economics and Technology). In his presentation, he summarized the main results of the project. According to Bertrand, by changing the refining process it is possible to reduce the content of 3-MCPD esters and related compounds in the products. Examples are the introduction of an additional washing step, the use of citric acid during deodorization or the change of the temperature-time profile during deodorization (two-step deodorization). Furthermore, the choice of appropriate raw material is a further component for the reduction of the esters in fats and oils.
The final presentation in this session was given by Voon Phooi Tee from the Malaysian Palm Oil Board. She presented the results of a study to assess toxicity of 3-MCPD esters, by performing cytotoxicity assays at cellular level in vitro and by conducting an acute oral toxicity study using rats. In these studies different 3-MCPD-esters were used. These studies could give more insight in the amount of hydrolysis of 3-MCPD esters. In this oral toxicity study, in total 30 rats were (=5 per sex per group) fed with a single dose of 3-MCPD esters at 50, 200 and 400 ppm for 14 days. Results showed that 3-MCPD esters have no effects on mortality, body weight changes, organ weight changes, clinical observations or gross findings alteration for both genders.
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