Assessment of veterinary drug residues in food: Considerations when dealing with sub-optimal data.

The use of veterinary drugs in food-producing animals may lead to residues in animal-derived foodstuffs, potentially posing a risk to human safety. While the process of veterinary drug residue risk assessment continues to evolve as new data emerges, a recurring challenge is when sub-optimal or incomplete data are provided with the expectation of supporting a robust risk assessment. The Joint FAO/WHO Expert Committee on Food Additives (JECFA) is comprised of international experts who routinely deal with such data challenges when performing veterinary drug residue evaluations. Recent developments in veterinary drug residue risk assessment are described, including specific consequences of sub-optimal data during the risk assessment process. When feasible, practical solutions to such challenges are also highlighted. Case examples from recent JECFA veterinary drug evaluations are provided to clearly quantify and illustrate the concepts described. The information provided is intended to facilitate the generation of improved quality data, enabling more timely and robust veterinary drug residue risk assessments.

Japan Flavour and Fragrance Materials Association's (JFFMA) safety assessment of food-flavouring substances uniquely used in Japan that belong to the class of aliphatic primary alcohols, aldehydes, carboxylic acids, acetals and esters containing additional oxygenated functional groups.

We performed a safety evaluation using the procedure devised by the Joint FAO/WHO Expert Committee on Food Additives (JECFA) of the following four flavouring substances that belong to the class of 'aliphatic primary alcohols, aldehydes, carboxylic acids, acetals, and esters containing additional oxygenated functional groups' and are uniquely used in Japan: butyl butyrylacetate, ethyl 2-hydroxy-4-methylpentanoate, 3-hydroxyhexanoic acid and methyl hydroxyacetate. Although no genotoxicity study data were found in the published literature, none of the four substances had chemical structural alerts predicting genotoxicity. All four substances were categorised as class I by using Cramer's classification. The estimated daily intake of each of the four substances was determined to be 0.007-2.9 µg/person/day by using the maximised survey-derived intake method and based on the annual production data in Japan in 2001, 2005 and 2010, and was determined to be 0.250-600.0 µg/person/day by using the single-portion exposure technique and based on average-use levels in standard portion sizes of flavoured foods. Both of these estimated daily intake ranges were below the threshold of toxicological concern for class I substances, which is 1800 µg/person/day. Although no information from in vitro and in vivo toxicity studies for the four substances was available, these substances were judged to raise no safety concerns at the current levels of intake.

Magnesium stearate, a widely-used food additive, exhibits a lack of in vitro and in vivo genotoxic potential.

Magnesium stearate is widely used in the production of dietary supplement and pharmaceutical tablets, capsules and powders as well as many food products, including a variety of confectionery, spices and baking ingredients. Although considered to have a safe toxicity profile, there is no available information regarding its potential to induce genetic toxicity. To aid safety assessment efforts, magnesium sulfate was evaluated in a battery of tests including a bacterial reverse mutation assay, an in vitro chromosome aberration assay, and an in vivo erythrocyte micronucleus assay. Magnesium stearate did not produce a positive response in any of the five bacterial strains tested, in the absence or presence of metabolic activation. Similarly, exposure to magnesium stearate did not lead to chromosomal aberrations in CHL/IU Chinese hamster lung fibroblasts, with or without metabolic activation, or induce micronuclei in the bone marrow of male CD-1 mice. These studies have been used by the Japanese government and the Joint FAO/WHO Expert Committee on Food Additives in their respective safety assessments of magnesium stearate. These data indicate a lack of genotoxic risk posed by magnesium stearate consumed at current estimated dietary exposures. However, health effects of cumulative exposure to magnesium via multiple sources present in food additives may be of concern and warrant further evaluation.

The Japan Flavour and Fragrance Materials Association's (JFFMA) safety assessment of acetal food flavouring substances uniquely used in Japan.

Using the procedure devised by the Joint FAO/WHO Expert Committee on Food Additives (JECFA), we performed safety evaluations on five acetal flavouring substances uniquely used in Japan: acetaldehyde 2,3-butanediol acetal, acetoin dimethyl acetal, hexanal dibutyl acetal, hexanal glyceryl acetal and 4-methyl-2-pentanone propyleneglycol acetal. As no genotoxicity study data were available in the literature, all five substances had no chemical structural alerts predicting genotoxicity. Using Cramer's classification, acetoin dimethyl acetal and hexanal dibutyl acetal were categorised as class I, and acetaldehyde 2,3-butanediol acetal, hexanal glyceryl acetal and 4-methyl-2-pentanone propyleneglycol acetal as class III. The estimated daily intakes for all five substances were within the range of 1.45-6.53 µg/person/day using the method of maximised survey-derived intake based on the annual production data in Japan from 2001, 2005, 2008 and 2010, and 156-720 µg/person/day using the single-portion exposure technique (SPET), based on the average use levels in standard portion sizes of flavoured foods. The daily intakes of the two class I substances were below the threshold of toxicological concern (TTC) - 1800 µg/person/day. The daily intakes of the three class III substances exceeded the TTC (90 µg/person/day). Two of these, acetaldehyde 2,3-butanediol acetal and hexanal glyceryl acetal, were expected to be metabolised into endogenous products after ingestion. For 4-methyl-2-pentanone propyleneglycol acetal, one of its metabolites was not expected to be metabolised into endogenous products. However, its daily intake level, based on the estimated intake calculated by the SPET method, was about 1/15 000th of the no observed effect level. It was thus concluded that all five substances raised no safety concerns when used for flavouring foods at the currently estimated intake levels. While no information on in vitro and in vivo toxicity for all five substances was available, their metabolites were judged as raising no safety concerns at the current levels of intake.

The JFFMA assessment of flavoring substances structurally related to menthol and uniquely used in Japan.

Using the procedure devised by the Joint FAO/WHO Expert Committee on Food Additives (JECFA), we performed safety evaluations on four flavoring substances structurally related to menthol (L-menthyl 2-methylbutyrate, DL-menthyl octanoate, DL-menthyl palmitate, and DL-menthyl stearate) uniquely used in Japan. While no genotoxicity study data were available in the literature, all four substances had no chemical structural alerts predictive of genotoxicity. Moreover, they all four are esters consisting of menthol and simple carboxylic acids that were assumed to be immediately hydrolyzed after ingestion and metabolized into innocuous substances for excretion. As menthol and carboxylic acids have no known genotoxicity, it was judged that the JECFA procedure could be applied to these four substances. According to Cramer's classification, these substances were categorized as class I based on their chemical structures. The estimated daily intakes for all four substances were within the range of 1.54-4.71 µg/person/day and 60-1250 µg/person/day, using the methods of Maximized Survey-Derived Intake and Single Portion Exposure Technique, respectively, based on the annual usage data of 2001, 2005, and 2010 in Japan. As the daily intakes of these substances were below the threshold of concern applied to class I substances viz., 1800 µg/person/day, it was concluded that all four substances raise no safety concerns when used for flavoring foods under the currently estimated intake levels.