Radioactivity and foods.

The purpose of this article is to describe and contrast two relationships between radiation and food--on the one hand, beneficial preservation of food by controlled exposure to ionizing radiation; and, on the other, contamination of food by accidental incorporation of radioactive nuclides within the food itself. In food irradiation, electrons or electromagnetic radiation is used to destroy microorganisms and insects or prevent seed germination. The economic advantages and health benefits of sterilizing food in this manner are clear, and numerous studies have confirmed that under strictly controlled conditions no undersirable changes or induced radioactivity is produced in the irradiated food. An altogether different situation is presented by exposure of food animals and farming areas to radioactive materials, as occurred after the major Soviet nuclear reactor accident at Chenobyl. This article furnishes the basic information needed to understand the nature of food contamination associated with that event and describes the work of international organizations seeking to establish appropriate safe limits for levels of radioactivity in foods.

[Radioactivity and food]. / La radiactividad y los alimentos.

Two topics relating to radioactivity and food are discussed: food irradiation for preservation purposes, and food contamination from radioactive substances. Food irradiation involves the use of electromagnetic energy (x and gamma rays) emitted by radioactive substances or produced by machine in order to destroy the insects and microorganisms present and prevent germination. The sanitary and economic advantages of treating food in this way are discussed. Numerous studies have confirmed that under strictly controlled conditions no undesirable changes take place in food that has been irradiated nor is radioactivity induced. Reference is made to the accident at the Chernobyl nuclear power station, which aroused public concern about irradiated food. The events surrounding the accident are reviewed, and its consequences with regard to contamination of different foods with radioactive substances, particularly iodine-131 and cesium-137, are described. Also discussed are the steps that have been taken by different international organizations to set limits on acceptable radioactivity in food.

Contamination of human milk with chlorinated pesticides in Guatemala and in El Salvador.

In Central America huge amounts of persistent organochlorine pesticides are being used. This paper presents data on organochlorine residues in human milk. The samples studied were collected from areas with different spraying patterns. The results show very high contamination rates with organochlorine pesticides, especially with DDT. The highest levels were found in cotton-growing areas. Compared with residue levels in areas where cotton is not grown the difference was found to be statistically significant. Many of the quoted values are among the highest reported for the Western World. However, very high residue levels were also found even in Guatemala City, suggesting that other than agricultural uses of pesticides are important contamination sources. It is believed that these high levels of pesticide residues in human milk reflect a high contamination among the population in general.

Correlation Between Total DDT Residues in Blood and Fat of Beef Animals 1.

In Guatemala, where in certain regions heavily pesticide-sprayed cotton fields are interspersed with pastures for cattle, pesticide residues in beef fat represent a problem. Organochlorine pesticides are still widely used and even if the use of DDT has been decreasing over the last few years, this pesticide is still a major food contaminant. The present study was undertaken to establish if a correlation between total DDT levels in blood and fat could be found. Samples of blood and fat from 30 bovines were analyzed by gas-liquid chromatography. The "ppm in fat/ppb in blood" ratio was calculated to be 0.96 ± 0.39 (mean ± S.D.), the regression line to be Y = 2.54 + 0.61 X (Y = ppb in blood, X = ppm in fat) and the correlation coefficient to be 0.889. It was established that blood analysis may be used to estimate, before slaughter, if the residue levels in the fat are exceeding the legal limits.

Contaminants in human milk.

There is a paucity of information regarding excretion of contaminants in human milk, due to experimental difficulties and until recently a general lack of interest. Because of the high fat content of milk and as its acidity is higher than that of plasma, nearly all liposoluble and basic agents consumed by the mother will be excreted in the milk. Distinction must be made between, on the one hand drugs and social toxicants such as smoking and alcohol, whose intake can be stopped or limited during pregnancy and lactation, and ecological toxicants present in a polluted environment to which the mother is exposed. Cases have occurred of heavy prenatal and postnatal intoxication of infants with hexachlorobenzene in Turkey and methylmercury in Iraq due to consumption of fungicide-treated seed wheat by pregnant and lactating mothers. Recent attention has been concentrated on contamination of milk with organochlorine compounds such as DDT and PCB's, that are found in many parts of the world. The heaviest contamination with DDT has been found in Guatemala, resulting in suckling infants consuming many times the Acceptable Daily Intake of this compound proposed by WHO, with unknown future effects.