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Toxicological evaluation of some enzymes, modified starches and certain other substances
296
REVIEWS OF RECENT PUBLICATIONS
report enabled the Sub-Committee to reclassify several substances in group A and also to include some previously unconsidered compounds in this category. These substances, on which no further work is urgently required, include carrageenan, polyoxyethylene sorbitan esters, polyoxyethylene (8) and (40) stearates, polyglycerol esters of polycondensed fatty acids of castor oil, furcelleran, xanthan gum and propylene glycol/glycerol esters of fatty acids and lactic acid. It is interesting to note that whereas the 1970 Report requested 18month feeding studies in the mouse for several compounds, it is now recommended that such a study should be carried out on polyoxyethylene sorbitan mono-oleate, as a representative of the whole group of polyoxyethylene sorbitan esters. Additives reclassified into group B include sucrose esters and sucroglycerides. Less than 10 ppm methyl alcohol and less than 50 ppm dimethylformamide are now considered acceptable as contaminants in these materials. Adequate short- and long-term studies on dimethylformamide are not available and studies of this contaminant in two species are considered essential before a higher classification can be considered for these food additives. Citroglycerides are hydrolysed in vitro to simple glycerides and citric acid but further data on the extent of in rive hydrolysis by human and animal enzymes are required before the next review. A long-term feeding study on gum ghatti is also required but is not considered of high priority. A representation that metabolic studies in man on Emulsifier YN could only be carried out using radioactive material, which in this case would not be justified, has been accepted by the PSC, but the results of long-term studies at present being carried out at BIBRA are required by the time of the next review. A single 18-month feeding study in mice on sorbitan monostearate is to be accepted as representative of the whole group of sorbitan esters of fatty acids. Long-term feeding studies in mice are not required on all individual compounds. Results of short-term feeding studies in the rat and mouse on the mono-oleate and monolaurate esters are required before the next review. Also by that time, results of long-term studies on the stearoyl lactylates in two species other than the dog are required, together with investigations showing that man metabolizes these compounds in the same way as other species. While polyglycerol esters of dimerized fatty acids of soya-bean oil are acceptable for tin-greasing with a transfer limit of 20 ppm into the food, adequate metabolic studies and short-term studies in several species are still considered necessary. Finally, two compounds were classified in group E: insufficient data were available on tamarind-seed flour, and adequate long-term feeding tests on sodium lauryl sulphate were lacking.
Toxicological Evaluation of Some Enzymes, Modified Starches and Certain Other Substances.
Joint FAO/WHO Expert Committee on Food Additives. WHO/Food Add. 72.1; F.A.O. Nutr. Mtg Rep. Ser. no. 50A, Rome 1972. pp. 109. £0.60. Monographs have now been issued on the toxicological evaluation of some enzymes, modified starches and certain other substances considered in the report of the Fifteenth Meeting of the Joint FAO/WHO Expert Committee on Food Additives (Tech. Rep. Ser. Wld Hlth Org. 1972, 488) held in Rome in June 1971, but the publication of specifications for the identity and purity of these materials is still awaited. These supporting monographs have been drawn up for six enzymes derived from microbial sources, 11 modified starches, caramel colourings made by the ammonia process, esters of glycerol and thermally-oxidized soya-bean fatty acids, hexamethylenetetramine, micro-
REVIEWS OF RECENT PUBLICATIONS
297
crystalline cellulose, propylene glycol alginate, calcium and sodium salts of stearoyl lactylic acid and tin and stannous chloride. It is interesting to note that the new data on esters of glycerol and thermally-oxidized soya-bean fatty acids and on calcium and sodium stearoyl lactylates may have been responsible for the recent up-grading of these two materials in the U K Food Additives and Contaminants Committee's recent supplementary report on emulsifiers and stabilizers (see previous review). Furthermore, it is understood that, both in the U K and within the EEC, a new instrument or directive will be drawn up for modified starches, which are now exempt from regulations covering emulsifiers and stabilizers in food. The toxicological data that have been evaluated will probably be used as a basis for permitted lists, and further data on metabolism in man may well be required in the near future. The situation with regard to caramel colourings made by the ammonia process has been complicated by the discovery of imidazoles and pyrazines in these materials. Since 4methylimidazole has been shown to be a convulsant when administered orally to rabbits, mice and chicks, long-term feeding studies on caramel colourings prepared by the ammonia or ammonium sulphate process and containing several levels of 4-methylimidazole are required by 1974. The publication of adequate specifications for these and other materials considered at the Expert Committee's meeting in 1971 is eagerly awaited.
Phosphorus and Calcium Intakes by Dutch Diets. By M. I. El-Shaarawy, Doctoral Thesis, State University of Utrecht, 1971. The idea of phosphorus poisoning immediately conjures up visions of Victorian match factories--lucifers and luminous paint rather than food additives. However Dr. EI-Shaarawy expresses concern at the "growing application of phosphorus containing food additives". Nearly every foodstuff normally contains phosphorus and he feels this natural phosphorus content should be considered when assessing the risk associated with the use of these additives. The metabolism of phosphorus is closely interlinked with that of calcium, so dietary calcium levels are important in any study of dietary phosphorus. This is especially so in assessments of the phosphorus intakes of underdeveloped countries where the calcium intake is likely to be low. In general, a higher phosphorus intake may be allowed for populations with a higher calcium intake. Fortunately we are not threatened with the unpleasant consequences of ingesting pure phosphorus as were the match makers. Most of the phosphorus naturally in, or added to, food is in the form of organic or inorganic compounds. Overdosage with such compounds leads to metastatic calcification in rat kidneys, which may be more susceptible than human kidneys to damage by phosphates. At similar dose levels, guinea-pigs have shown calcification of the soft tissues. On the basis of these rat experiments the FAO/WHO Joint Expert Committee on Food Additives concluded in its seventh report that the lowest phosphorus level likely to be nephrocalcinie to man would be around 100 mg P/kg body weight/day. The Acceptable Daily Intake (ADD was given as 30-70 mg P/kg body weight, depending on the diet. Dr. EI-Shaarawy contends that the safety margin allowed by this ADI is insu~cient, especially for groups with a low calcium intake. Old people and children may come into this category even in highly developed industrial communities.
REVIEWS OF RECENT PUBLICATIONS
report enabled the Sub-Committee to reclassify several substances in group A and also to include some previously unconsidered compounds in this category. These substances, on which no further work is urgently required, include carrageenan, polyoxyethylene sorbitan esters, polyoxyethylene (8) and (40) stearates, polyglycerol esters of polycondensed fatty acids of castor oil, furcelleran, xanthan gum and propylene glycol/glycerol esters of fatty acids and lactic acid. It is interesting to note that whereas the 1970 Report requested 18month feeding studies in the mouse for several compounds, it is now recommended that such a study should be carried out on polyoxyethylene sorbitan mono-oleate, as a representative of the whole group of polyoxyethylene sorbitan esters. Additives reclassified into group B include sucrose esters and sucroglycerides. Less than 10 ppm methyl alcohol and less than 50 ppm dimethylformamide are now considered acceptable as contaminants in these materials. Adequate short- and long-term studies on dimethylformamide are not available and studies of this contaminant in two species are considered essential before a higher classification can be considered for these food additives. Citroglycerides are hydrolysed in vitro to simple glycerides and citric acid but further data on the extent of in rive hydrolysis by human and animal enzymes are required before the next review. A long-term feeding study on gum ghatti is also required but is not considered of high priority. A representation that metabolic studies in man on Emulsifier YN could only be carried out using radioactive material, which in this case would not be justified, has been accepted by the PSC, but the results of long-term studies at present being carried out at BIBRA are required by the time of the next review. A single 18-month feeding study in mice on sorbitan monostearate is to be accepted as representative of the whole group of sorbitan esters of fatty acids. Long-term feeding studies in mice are not required on all individual compounds. Results of short-term feeding studies in the rat and mouse on the mono-oleate and monolaurate esters are required before the next review. Also by that time, results of long-term studies on the stearoyl lactylates in two species other than the dog are required, together with investigations showing that man metabolizes these compounds in the same way as other species. While polyglycerol esters of dimerized fatty acids of soya-bean oil are acceptable for tin-greasing with a transfer limit of 20 ppm into the food, adequate metabolic studies and short-term studies in several species are still considered necessary. Finally, two compounds were classified in group E: insufficient data were available on tamarind-seed flour, and adequate long-term feeding tests on sodium lauryl sulphate were lacking.
Toxicological Evaluation of Some Enzymes, Modified Starches and Certain Other Substances.
Joint FAO/WHO Expert Committee on Food Additives. WHO/Food Add. 72.1; F.A.O. Nutr. Mtg Rep. Ser. no. 50A, Rome 1972. pp. 109. £0.60. Monographs have now been issued on the toxicological evaluation of some enzymes, modified starches and certain other substances considered in the report of the Fifteenth Meeting of the Joint FAO/WHO Expert Committee on Food Additives (Tech. Rep. Ser. Wld Hlth Org. 1972, 488) held in Rome in June 1971, but the publication of specifications for the identity and purity of these materials is still awaited. These supporting monographs have been drawn up for six enzymes derived from microbial sources, 11 modified starches, caramel colourings made by the ammonia process, esters of glycerol and thermally-oxidized soya-bean fatty acids, hexamethylenetetramine, micro-
REVIEWS OF RECENT PUBLICATIONS
297
crystalline cellulose, propylene glycol alginate, calcium and sodium salts of stearoyl lactylic acid and tin and stannous chloride. It is interesting to note that the new data on esters of glycerol and thermally-oxidized soya-bean fatty acids and on calcium and sodium stearoyl lactylates may have been responsible for the recent up-grading of these two materials in the U K Food Additives and Contaminants Committee's recent supplementary report on emulsifiers and stabilizers (see previous review). Furthermore, it is understood that, both in the U K and within the EEC, a new instrument or directive will be drawn up for modified starches, which are now exempt from regulations covering emulsifiers and stabilizers in food. The toxicological data that have been evaluated will probably be used as a basis for permitted lists, and further data on metabolism in man may well be required in the near future. The situation with regard to caramel colourings made by the ammonia process has been complicated by the discovery of imidazoles and pyrazines in these materials. Since 4methylimidazole has been shown to be a convulsant when administered orally to rabbits, mice and chicks, long-term feeding studies on caramel colourings prepared by the ammonia or ammonium sulphate process and containing several levels of 4-methylimidazole are required by 1974. The publication of adequate specifications for these and other materials considered at the Expert Committee's meeting in 1971 is eagerly awaited.
Phosphorus and Calcium Intakes by Dutch Diets. By M. I. El-Shaarawy, Doctoral Thesis, State University of Utrecht, 1971. The idea of phosphorus poisoning immediately conjures up visions of Victorian match factories--lucifers and luminous paint rather than food additives. However Dr. EI-Shaarawy expresses concern at the "growing application of phosphorus containing food additives". Nearly every foodstuff normally contains phosphorus and he feels this natural phosphorus content should be considered when assessing the risk associated with the use of these additives. The metabolism of phosphorus is closely interlinked with that of calcium, so dietary calcium levels are important in any study of dietary phosphorus. This is especially so in assessments of the phosphorus intakes of underdeveloped countries where the calcium intake is likely to be low. In general, a higher phosphorus intake may be allowed for populations with a higher calcium intake. Fortunately we are not threatened with the unpleasant consequences of ingesting pure phosphorus as were the match makers. Most of the phosphorus naturally in, or added to, food is in the form of organic or inorganic compounds. Overdosage with such compounds leads to metastatic calcification in rat kidneys, which may be more susceptible than human kidneys to damage by phosphates. At similar dose levels, guinea-pigs have shown calcification of the soft tissues. On the basis of these rat experiments the FAO/WHO Joint Expert Committee on Food Additives concluded in its seventh report that the lowest phosphorus level likely to be nephrocalcinie to man would be around 100 mg P/kg body weight/day. The Acceptable Daily Intake (ADD was given as 30-70 mg P/kg body weight, depending on the diet. Dr. EI-Shaarawy contends that the safety margin allowed by this ADI is insu~cient, especially for groups with a low calcium intake. Old people and children may come into this category even in highly developed industrial communities.