Transfer And Incorporation Of Tritium In Milk And Grass Constituents In Natural Conditions

Le tritium suscite un interet croissant en raison de son importance potentielle comme contaminant radio-actif du milieu, liee au developpement de l'industrie nucleaire. Des experiences de contamination volontaire de prairies, par depot d'eau tritiee, ont permis de calculer le taux d'incorporation du tritium dans l'herbe et de suivre 1'evolution de la contamination apres depat a differentes saisons. Le taux et la vitesse de transfert ainsi que la repartition du tritium dans le lait produit par des vaches consommant de l'herbe contaminee ont aussi ete determines; ces donnees sont comparees a celles obtenues dans le cas de la contamination du lait resultant de l'ingestion repetee d'eau tritiee: il apparait que l'incorporation relative du tritium daps la matiere organique du lait est jusqu'a 10 fois plus elevee dans le cas de consommation d'herbe contaminee que dans celui d'eau d'abreuvage contaminee. Les resultats indiquent un transfert tres rapide dans le cas d'ingestion d'eau contaminee, alors que dans le cas d'ingestion d'herbe contaminee le niveau maximum de contamination a ete observe au quatrieme jour. // There is an increasing interest in tritium because of its potential importance as a radioactive environmental contaminant associated with the development of nuclear industry. Deliberate experimental contamination of grazing land by the deposition of tritiated water has made it possible to calculate the level of incorporation of tritium into the grass and to follow the pattern of contamination after deposition at different seasons. It was also possible to determine the level and rate of transfer and thence the distribution of tritium in the milk produced by cows eating the contaminated grass. These data are compared with those obtained for the contamination of milk resulting from the repeated ingestion of tritiated water. It appears that the tritium in the organic material is 10 times higher in the case of cows fed with contaminated grass than for cows drinking tritiated water. The results show a very rapid transfer in the case of the intake of contaminated water while, in the case of ingestion of grass, the maximum level of contamination was found on the 4th day.