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Biomedical subjects

R Truhaut

Publications and source records attributed to R Truhaut.

At least 163 records · Page 9Linked to original sources
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The concept of the acceptable daily intake: an historical review.

In the first section the sequence of events is outlined which leads to the author's proposal to consider the concept of acceptable daily intake (ADI) for pesticide residues. He developed his theory referring to specific aspects during meetings with experts on the toxicological evaluation of chemical agents which become introduced into foodstuffs intentionally or unintentionally. These meetings were organized periodically by the European Council or Joint FAO/WHO Expert Committees on food additives (JECFA) or pesticide residues (JMPR). The general principles of the ADI evaluation are briefly described as being based on the determination (after extended absorption) of a no-effect dose level in an appropriate animal species; followed by the application, for the extrapolation of the results in animals to humans, of safety factors taking into account the interspecies sensitivity variations and individual sensitivity variations in the groups of essentially heterogeneous human consumers. It is pointed out that the ADI value, which depends on a series of factors, is not a constant, but a guide serving to calculate the admissible limits of diverse chemical agents incorporated in foodstuffs. It must take into account the usual normalities between medium terms of consumption varying a lot with the countries and the various consumer groups. It is clearly noted that, because of the fluctuations in the type and the quantities of absorbed diets, the ADI is in reality an integrated value with regard to the time, a notion that is often forgotten. Other ideas are developed, in particular on the adoption of a temporary ADI and on the concept of a non-specified ADI.

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[Toxicologic evaluation of irradiated corn starch by long term experimentation with rats].

Maize starch pasteurized by irradiation was fed to OFA rats (Sprague Dawley derived) in an uncooked form (irradiated at 300 krad.) and in a cooked form (irradiated at 300 and 600 krad.) at dietary level of 62%. A six month toxicity trial was performed with uncooked starch and a 24 month trial with cooked starch. At the same time a reproduction study was conducted, over 3 generations with 2 litters per generation, using both uncooked and cooked irradiated starch. The parent generation (Fo) was randomly selected from animals in the feeding study and after the production of the F1a and F1b generations they were returned to that study. Control groups corresponding to each form of starch were established. They were fed the same diet except that the starch was not irradiated. The results of the various investigations conducted during the study (behavior, growth, mortality, haematology, serum biochemistry, histopathology) did not reveal any toxicological effect due to treatment, nor any effect on reproduction. No significant differences were shown between treated and control group.

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[Toxicologic and pharmacologic study of tributyltin oxide (TBTO)].

Toxicological study on bis-(tributyl-tin) oxyde shows a delayed toxicity of this compound in acute experiments. The same result is obtained in sub-chronic study. Most of the animals die after a great loss of weight. In pharmacological study, T. B. T. O. depresses central nervous system, but his action on ortho and parasympathetic system is slight and non specific. In rat, rabbit and dog, the effect is a fall in blood pressure that result from a depression of the vascular smooth muscle. The death of the animal is due to respiratory arrest by a central mechanism.

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PubMedDate not supplied

[Recent progress in the evaluation of the dangers of chemical carcinogens].

The paper begins with a brief historical account of the production of cancers through exposure to chemicals, first in humans, then in animals, followed by the identification of chemically defined agents. Such agents have progressively been discovered in the most diverse chemical families. The present classification of chemical carcinogens includes those demonstrated as carcinogenic for humans by adequate epidemiological studies and those considered, on more or less limited basis, as probably or possibly carcinogenic for humans. The first category is divided into three groups: complex mixtures-defined chemicals-industrial operations. The materials and compounds of the last two categories are called "potential carcinogens". The present international trend is to consider them as dangerous for humans as long as their innocuousness has not been demonstrated. The author stresses that the compounds of the three categories are either manufactured or developed by man, or of natural origin. The latter seem, by far, to cause the highest percentage of cancers in humans. Then he develops, in their general outline, the pluridisciplinary methodological approaches in view to revealing the carcinogenic potentialities of compounds to which man can be exposed in various fields (occupational, food, therapeutic, household,...). This leads him to underline the factors of uncertainty involved by the extrapolation to humans of the results of animal experimentation and the importance of observations on groups of humans. He also stresses the multifactors which intervene in the various steps of evolution towards malignancy (initiation, promotion, influence of synergistic or antagonistic factors-role of "free radicals" the type of which is the superoxyde anion radical O2-.). He emphasizes the difficulties of interpretation resulting from the multifactorial nature of the processes of malignancy, as well as the interest of revealing the intimate mechanisms of activity (genotoxic mechanisms with the transformation of certain genes: protooncogenes to oncogenes, epigenetic mechanisms); this demonstration becomes more and more performant thanks to the spectacular progress of basis sciences to which cancer evaluation methodology appeals more and more. Evaluation of carcinogenic risks which, together with early diagnosis, constitutes a fundamental basis of cancer prevention is thus considerably improved. The author is thus led to discuss the possibility of setting threshold values, at least for some types of carcinogenic chemicals. In the end, he insists upon the necessity of an active international cooperation for carcinogenicity studies, either experimental or epidemiological.

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