四アルキル鉛中毒

Abstract

The present writer's address on this subject was given at the 82 nd ASSEMBLY of KANTO DISTRICT of JAPAN ASSOCIATION OF INDUSTRIAL HEALTH on Nov. 15, 1969. Since this address was given, the fate of tetra-alkyl lead has greatly changed in this country. This article has been rewritten summarizing the contents of the address with the writer's sense of the time at the meeting and concerns mainly with the results of the work of the writer and his colleagues.1) History. Regarding the tetraethyl lead (TEL) in U.S.A. the manufacture and the use started in 1923, and in Japan the first use began in 1931 and the manufacture in 1938. About the tetramethyl lead (TML) in U.S.A. the manufacture and the use began in 1960, and in Japan the first use in 1963. With regard to their physical mixture (PM) and chemically reacted products (CR) of tetraalkyl lead in U.S.A., the manufacture and the use began in 1962 and in Japan the first use in 1963.2) Chemistry. The odor of TEL is like the smell of acetylene gas or the thick solution of calcium chlorate.3) The method of manufacturing. The manufacturing of TEL in Japan was formerly done by lead-sodium-alloy method.4) The chances of poisoning. The possibility is mostly occurring at the time of manufacturing, transportation, blending to gasoline, misusing leaded-gasoline and tank-cleaning.5) Toxicity. The toxicity (M.L.D.) differs depending upon the route of absorption and the grade of purity of the material as well as upon the species, the maturity, the nourishment and the individuality of the testing animals, and upon the temperature of the environment (season), etc.On TEL : The experiment through respiratory tract on mice with the air of 0.65 mgPb/l resulted in deaths by inhalation for 210 minutes in matured, 140 minutes in immatured in summer time, and in winter time 30 minutes inhalation in both maturity. No difference due to the sex was observed.By the experiment through skin on matured rabbits M. L. D. was found proving when TEL was applied at the rate of 1.5 cc/kg in summer time ; 1.2 cc/kg in winter time ; 0.5 cc/kg under malnutrition ; and 0.5 cc/kg on an immatured individual.The experiment of M. L. D. through digestive tract on matured rabbits decided on 0.024 cc/kg in summer time and in 0.018 cc/kg winter time.On TML : By the experiment through skin on matured rabbits M. L. D. proved to be 1.7 cc/kg (Ethyl product) in summer time, and 2.0 cc/kg (Du Pont product) in winter time.By the experiment through digestive tract on matured rabbits, M. L. D. proved to be 0.013 cc/kg in summer time, and 0.012 cc/kg in winter time.Thus toxicity through skin revealed TEL > TML and through digestive tract, TEL < TML, This might be partly due to volatility.6) Pathology. Pathological findings of TEL as well as TML poisoned animals showed the same nature, though the grades were different, those of TML being stronger than those of TEL. The changes were observed mostly in the central nervous system, lungs, liver, etc. However, pathognomonic findings were not proved.7) Symptom.(a) In human cases : Symptoms experienced in patients were as follows, when subacute as well as chronic poisonings were prevalent among the workers of TEL manufacturing plants.Symptoms of the early stage of poisoning : insomnia, nightmare, anorexia.Symptoms that were increased by the length of factory service : pallor face, dull feeling, night sweat, dizziness, heavy head, headache, memory deficiency, molilalia, excitement, melancholia, stricture feeling in throat, pain in throat and chest, compressed feeling in stomach, and tremor.Thus the symptoms of circulatory and central nervous systems were prevalent.Measurable data : They are the decreases in body weight and in the difference of the chest girth on extreme breathing as well as in the circumference of the upper arm on maximum bending, in the muscular strength of arm and back, in body temperature and