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1121. More on environmental radioactivity
552
"I'HE CHEMICAL ENVIRONMENT
The present study was conducted on pooled fractions of steam-refined PA which contained either saturated or aromatic hydrocarbons. These fractions accounted for almost all the ultraviolet fluorescence of asphalt and were thus considered likely to contain all probable carcinogenic hydrocarbons. Thrice-weekly skin painting of the pooled fractions produced local carcinomas in over 40~o of the animals examined at autopsy. These animals had received in all 72-242 treatments. The tumours were identified histologically as leiomyosarcoma, epidermoid carcinoma and basal cell or baso-squamous carcinoma. Other animals displayed well-developed papillomas, hyperkeratosis and epilation. It was thought unlikely that more detailed fractionation of PA for carcinogenicity tests would yield any valuable information, because of the variable chemical composition of PA. 1121. More on environmental radioactivity
Ellis, R. E. (1965). An appraisal of the current fall-out levels and their biological significance. Physics Med. Biol. 10, 153. Mayneord, W. V. (1965). Mans' natural radiation environment. In Radioaktive Isotope in Klinik und Forschung, Vol. VI. Proceedings of International Symposium at Bad Gastein, Austria, in January 1964. Urban & Schwarzenberg, Munich-Berlin, 1965. Environmental radioactivity has been a recurring feature in these pages, the main villains of the piece being strontium-90 (9°Sr), caesium-137 (~37Cs) and iodine-131 (13~I) (Cited in F.C.T. 1964, 2, 598; ibid 1965, 3, 517). A useful appraisal of current fall-out levels and their biological significance is provided by Ellis (cited above). This covers the range of levels in members of a particular community due to variations in age and diet and local meteorological conditions and an interpretation of the risk to the individual from chronic radiation. Gonads, cells lining bone surfaces and bone marrow are most readily affected by chronic radiation, and irradiation of these tissues may cause hereditary defects, bone turnouts and leukaemia respectively. Carcinomas of the thyroid, particularly in children, constitute another hazard. Doses received from fallout by these critical tissues are in general well below those of the natural radiation levels of about 100 mrad/yr. Possible exceptions are some Arctic populations. On account of the high 137Cs content of reindeer and caribou meat, Laplanders and Eskimos receive at least 100 times as much 137Cs in their foods as do other communities. Thus although a typical adult 137Cs burden is 150 pc ~37Cs/g K, those reported for Lapps and Eskimos are usually 10004000 pc ~37Cs/g K and values as high as 25,700 pc 137Cs/g K have been reported. It is a sobering thought that although the radiation dose from one particular series of weapon tests will have been received within 50-60 yr for most nuclides, this is not true for carbon-14, which has a mean life of 8000 yr, so that only 8 ~o of the dose commitment will have been received in this period. Much attention is paid to the UK levels of 9°St and ~37Cs in drinking water, milk, total diet and in man, but we need hardly burden our readers with facts that we have brought to their attention before. Mayneord (cited above) discusses the natural radioactivity of man's environment, particularly with respect to radon (Rn). Twelve isotopes of Rn are known but the most important are 222Rn, 22°Rn and 219Rn, produced by disintegration of radium-226 (226Ra), 224Ra and 223Ra, and having half-lives of 3.82 days, 54-5 sec and 3-92 sec, respectively. 222Rn provides approximately 3 ~o of the total natural radiation dose in man; in the body about 70 ~o is present in fat and 11 ~o in bone marrow. Relatively high concentrations of Rn are found in natural waters and in particular in spa waters such as those at Bad Gastein. Cornish waters also are rich in Rn. Drinking water provides most of the ingested Rn but since it is rapidly removed by boiling it is unlikely to present any hazard in tea- and coffee-
NATURAL PRODUCTS
553
drinking communities. In fact no ill-effects have been reported following the drinking of Rn-eontaining water. It is argued that not until more analytical and biological data are available will there be a sound basis on which to establish maximum permissible levels of Rn in food or water.
N A T U R A L PRODUCTS 1122. Reflections on acetaldehyde: Past and present
Amerine, M. A. (1964). Acetaldehyde and related compounds in foods. J. Fd Sci. Technol. 1, 87. Since acetaldehyde (I) is produced during alanine breakdown and also in carbohydrate metabolism in micro-organisms and higher plants and animals, it occurs in small amounts in a large number of foods, in which its presence may have adverse or favourable effects on quality. I is at least partly responsible, for example, for deleterious changes in fruit during storage and for off-flavour in certain frozen vegetables. On the other hand, it is an important ethanol intermediate in fermentation processes. In this paper, largely devoted to metabolic pathways leading to production of I in many micro-organisms, Amerine points out that I is present in wines in widely varying amounts. The content in California wines tested varied from 9 to 217 mg/l, while some Spanish sherries were found to contain as much as 500 mg/1. I exists in wines in three forms: free, as a sulphite addition compound and as addition complexes with polyphenols. One reason for adding sulphur dioxide to wine is to reduce the level of free I, which tends to have an adverse effect on quality. The content of I in wines appears to increase with age, but in Russian brandy the opposite effect has been found, the older spirits containing far less aldehyde and more acetal than the new..A Russian study (Denshchikov et al. Trud. tsent, nauehnoizsled. Inst. pivovar, bezalk, vinnoi Prom. 1962, (9), 14) of the aldehyde content of a beer fermentation mash showed that the aldehydes gradually disappeared during the fermentation, but failed to demonstrate conclusively that I was one of the aldehydes concerned. I has received little toxicological attention compared with its close relative formaldehyde, which is biologically-speaking a very different kettle of fish. Its subcutaneous effects were studied some years ago in Japan by Watanabe & Sugimoto (Gann 1956, 47, 599) and it is worthwhile to outline in this abstract the results they obtained. In this study, gradually increasing doses of I, ranging from 0.5 ml of a 0.5 Yo solution to 1.5 ml of a 5 % solution were injected subcutaneously into rats, twice weekly for 3 wk and thereafter once weekly. Of 14 animals which survived 76-81 injections, 4 developed sarcomas at the injection site. The authors claim that while this incidence is not high, it cannot be considered insignificant, and they suggest that this result, coupled with earlier findings with formaldehyde and urotropin, point to some carcinogenicity of the aldehyde group. [Readers of the comments on subcutaneous sarcoma studies in the previous issue of the Journal (Cited in F.C.T. 1966, 4, 454) will realize that, in discussing these papers together, we are not advocating abstinence from the preprandial sherry!] 1123. Mahogany dust: A new sensitizer Morgan, J. W. W. & Wilkinson, D. S. (1965). Sensitization to Khaya anthotheca. Nature, Lond. 207, I101. African mahogany is derived from the genus Khaya and commercial supplies consist chiefly of K. ivorensis and K. anthotheca, with smaller amounts of K. grandifoliola. About 2 yr ago an outbreak of dermatitis occurred in about 10~o of the employees in a factory concerned with the processing of this timber and a similar outbreak prompted the present investigation.
"I'HE CHEMICAL ENVIRONMENT
The present study was conducted on pooled fractions of steam-refined PA which contained either saturated or aromatic hydrocarbons. These fractions accounted for almost all the ultraviolet fluorescence of asphalt and were thus considered likely to contain all probable carcinogenic hydrocarbons. Thrice-weekly skin painting of the pooled fractions produced local carcinomas in over 40~o of the animals examined at autopsy. These animals had received in all 72-242 treatments. The tumours were identified histologically as leiomyosarcoma, epidermoid carcinoma and basal cell or baso-squamous carcinoma. Other animals displayed well-developed papillomas, hyperkeratosis and epilation. It was thought unlikely that more detailed fractionation of PA for carcinogenicity tests would yield any valuable information, because of the variable chemical composition of PA. 1121. More on environmental radioactivity
Ellis, R. E. (1965). An appraisal of the current fall-out levels and their biological significance. Physics Med. Biol. 10, 153. Mayneord, W. V. (1965). Mans' natural radiation environment. In Radioaktive Isotope in Klinik und Forschung, Vol. VI. Proceedings of International Symposium at Bad Gastein, Austria, in January 1964. Urban & Schwarzenberg, Munich-Berlin, 1965. Environmental radioactivity has been a recurring feature in these pages, the main villains of the piece being strontium-90 (9°Sr), caesium-137 (~37Cs) and iodine-131 (13~I) (Cited in F.C.T. 1964, 2, 598; ibid 1965, 3, 517). A useful appraisal of current fall-out levels and their biological significance is provided by Ellis (cited above). This covers the range of levels in members of a particular community due to variations in age and diet and local meteorological conditions and an interpretation of the risk to the individual from chronic radiation. Gonads, cells lining bone surfaces and bone marrow are most readily affected by chronic radiation, and irradiation of these tissues may cause hereditary defects, bone turnouts and leukaemia respectively. Carcinomas of the thyroid, particularly in children, constitute another hazard. Doses received from fallout by these critical tissues are in general well below those of the natural radiation levels of about 100 mrad/yr. Possible exceptions are some Arctic populations. On account of the high 137Cs content of reindeer and caribou meat, Laplanders and Eskimos receive at least 100 times as much 137Cs in their foods as do other communities. Thus although a typical adult 137Cs burden is 150 pc ~37Cs/g K, those reported for Lapps and Eskimos are usually 10004000 pc ~37Cs/g K and values as high as 25,700 pc 137Cs/g K have been reported. It is a sobering thought that although the radiation dose from one particular series of weapon tests will have been received within 50-60 yr for most nuclides, this is not true for carbon-14, which has a mean life of 8000 yr, so that only 8 ~o of the dose commitment will have been received in this period. Much attention is paid to the UK levels of 9°St and ~37Cs in drinking water, milk, total diet and in man, but we need hardly burden our readers with facts that we have brought to their attention before. Mayneord (cited above) discusses the natural radioactivity of man's environment, particularly with respect to radon (Rn). Twelve isotopes of Rn are known but the most important are 222Rn, 22°Rn and 219Rn, produced by disintegration of radium-226 (226Ra), 224Ra and 223Ra, and having half-lives of 3.82 days, 54-5 sec and 3-92 sec, respectively. 222Rn provides approximately 3 ~o of the total natural radiation dose in man; in the body about 70 ~o is present in fat and 11 ~o in bone marrow. Relatively high concentrations of Rn are found in natural waters and in particular in spa waters such as those at Bad Gastein. Cornish waters also are rich in Rn. Drinking water provides most of the ingested Rn but since it is rapidly removed by boiling it is unlikely to present any hazard in tea- and coffee-
NATURAL PRODUCTS
553
drinking communities. In fact no ill-effects have been reported following the drinking of Rn-eontaining water. It is argued that not until more analytical and biological data are available will there be a sound basis on which to establish maximum permissible levels of Rn in food or water.
N A T U R A L PRODUCTS 1122. Reflections on acetaldehyde: Past and present
Amerine, M. A. (1964). Acetaldehyde and related compounds in foods. J. Fd Sci. Technol. 1, 87. Since acetaldehyde (I) is produced during alanine breakdown and also in carbohydrate metabolism in micro-organisms and higher plants and animals, it occurs in small amounts in a large number of foods, in which its presence may have adverse or favourable effects on quality. I is at least partly responsible, for example, for deleterious changes in fruit during storage and for off-flavour in certain frozen vegetables. On the other hand, it is an important ethanol intermediate in fermentation processes. In this paper, largely devoted to metabolic pathways leading to production of I in many micro-organisms, Amerine points out that I is present in wines in widely varying amounts. The content in California wines tested varied from 9 to 217 mg/l, while some Spanish sherries were found to contain as much as 500 mg/1. I exists in wines in three forms: free, as a sulphite addition compound and as addition complexes with polyphenols. One reason for adding sulphur dioxide to wine is to reduce the level of free I, which tends to have an adverse effect on quality. The content of I in wines appears to increase with age, but in Russian brandy the opposite effect has been found, the older spirits containing far less aldehyde and more acetal than the new..A Russian study (Denshchikov et al. Trud. tsent, nauehnoizsled. Inst. pivovar, bezalk, vinnoi Prom. 1962, (9), 14) of the aldehyde content of a beer fermentation mash showed that the aldehydes gradually disappeared during the fermentation, but failed to demonstrate conclusively that I was one of the aldehydes concerned. I has received little toxicological attention compared with its close relative formaldehyde, which is biologically-speaking a very different kettle of fish. Its subcutaneous effects were studied some years ago in Japan by Watanabe & Sugimoto (Gann 1956, 47, 599) and it is worthwhile to outline in this abstract the results they obtained. In this study, gradually increasing doses of I, ranging from 0.5 ml of a 0.5 Yo solution to 1.5 ml of a 5 % solution were injected subcutaneously into rats, twice weekly for 3 wk and thereafter once weekly. Of 14 animals which survived 76-81 injections, 4 developed sarcomas at the injection site. The authors claim that while this incidence is not high, it cannot be considered insignificant, and they suggest that this result, coupled with earlier findings with formaldehyde and urotropin, point to some carcinogenicity of the aldehyde group. [Readers of the comments on subcutaneous sarcoma studies in the previous issue of the Journal (Cited in F.C.T. 1966, 4, 454) will realize that, in discussing these papers together, we are not advocating abstinence from the preprandial sherry!] 1123. Mahogany dust: A new sensitizer Morgan, J. W. W. & Wilkinson, D. S. (1965). Sensitization to Khaya anthotheca. Nature, Lond. 207, I101. African mahogany is derived from the genus Khaya and commercial supplies consist chiefly of K. ivorensis and K. anthotheca, with smaller amounts of K. grandifoliola. About 2 yr ago an outbreak of dermatitis occurred in about 10~o of the employees in a factory concerned with the processing of this timber and a similar outbreak prompted the present investigation.