致死濃度以下のパラチオンが水産動物に及ぼす影響

Abstract

Goldfish (Carassius auratus) and Japanese killifish (Oryzias latipes) were kept for a long time, about a month, in the water containing an insecticide, parathion (Diethyl-para-nitrcphenyl-thiophate) in various concentrations lower than its lethal value and its toxicity upon fish was observed. By the culture experiment it was known that the insecticide gave many racognizable effects upon fish even at low concentrations as 1/30 th of its 48h-TLm (median tolerance limit), i.e., the movement of gill opercula and pectoral fins of the fish was observed to decline until the above mentioned concentration of the insecticide (Fig. 2, 3). Retardness in growth of fish due to the decrease in the amount of food eaten was also apparent at these low concentrations (Fig. 4 Table 1). The results show us that the permissible concentration of parathion upon aquatic animals should be regarded as far lower than the value of 48h-TLm×0.1, which is now considered as might be permissible for general pollutants.