In order to make clear the toxicity of two kinds white gasoline containing tetraethyl lead (LG) and organic solvents besides tetraethyl lead (LBTX), the survival rate and the electrocorticogram (E.Co.G.) in rats injected with either of them intraperitoneally were analysed.
Thirtynine white male Wistar rats, weighing about 400 g and aged 7 months, were implanted with bipolar electrodes on the surface of the brain about 3 mm apart over the frontal and occipital lobes of the left hemisphere under Nembutal-ether anaesthesia. The rats were divided into two groups, each rat in one of them was intraabdominally injected with 1 ml/100 g of LG and each rat in the other with the same dosis of LBTX. Tetraethyl lead content of LG was 1. 0 ml/liter that is, 16.5 mg/kg body weight of rat, and LBTX contained 5% benzene, 10% toluene and 15% xylene and 70% LG, tetraethyl lead in LBTX becoming 11.6 mg/kg body weight of rat. RG and HG, used in the former experiment, are commercially available leaded regular and high-octane gasolines. Tetraethyl lead contents of RG and HG were 0.15 ml/liter and 1.41 ml/liter, i.e. the amount of tetraethyl lead in rat were 2.5 mg and 23.3 mg/kg body weight respectively.
Observations were made one month after recovery from the implant operation. Brain waves were recorded on one day before and at 1, 2, 3, 4, 5, 7 and 10 days after the injection. The original wave, the momentary waves of δ, θ, α, β₁ and β₂ in the E.Co.G. and each 10 second integral value of these brain waves were recorded at the same time, and the data for 5 to 10 minutes were analysed.
One to 4 days after the gasoline injection rats showed slowing of movements, a crouching posture and absence of reaction to stimuli. After fifth day from the gasoline injection, the rats in the LG group showed excessive tension, excitement and anxiety, and the rats in the LBTX group showed continuously the same symptoms as crouching posture and slowing of movements. But about half of the rats in the LBTX group showed delirium and were dead within 2 days after LBTX injection, while almost of the rats in the LG group were alive. The death rate of HG and LG group was similar with LBTX group.
The control E.Co.G. before the injection showed a dominant θ and marked α waves, and the amplitude of these waves ranged from 50 to 150 microvolts. One to 5 days after the gasoline injection the basic rhythm and the amplitude in the E.Co.G. decreased and this phenomenon was more marked in the LBTX group than in the LG group, that is, α wave on the 1st day, δ and β₂ waves on the 4th day and θ wave on the 5th day after the gasoline injection decreased significantly compared to those of the LG group. The α wave of the rats in the LG group increased markedly and dominantly 7 days after the LG injection. The E.Co.G. of rats in the serious state before death caused by LBTX showed high voltage fast waves, arhythmic pattern of the brain waves appearing and disappearing, and slow and fast brain waves.
From these results it was concluded that the toxicity of LBTX was stronger than that of LG.

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ガソリンは，石油系炭化水素による土壌汚染の代表的な物質である。本研究では，ガソリンの主成分であるメタン系炭化水素（アルカン類：n-ペンタン～n-ドデカン）に着目して発光バクテリアを用いた急性毒性試験を実施した。そして，アルカンの炭素数間での発光バクテリアに及ぼす急性毒性影響の違いについて検討を行った。

メタノール溶媒を伴わない100 vol％のアルカンを検液とした試験では，発光バクテリアの相対発光強度比に及ぼすアルカンの影響はかなり小さく，バクテリアが疎水性であるアルカン類を吸収できなかったと思われるため，アルカンの急性毒性を明確には評価できなかった。一方，メタノールに溶かしたアルカンを検液とした試験では，有意な結果を得ることができた。炭素数が高いアルカンほど，また濃度が高いほど相対発光強度比が一定値になるまでに掛かる時間が長くなった。アルカンの種類に関わらず，全体的には，アルカン濃度が高いほど相対発光強度比は低くなった。相対発光強度比に及ぼすアルカン濃度の影響は，炭素数が高いアルカンよりも炭素数が低いアルカンの方が強くなる傾向が見られた。これは，炭素数が高いアルカンほど発光バクテリアに及ぼす急性毒性影響に関する反応速度が低くなることを推量させた。それゆえ，本試験条件においてアルカンに関する急性毒性評価を行う場合，反応時間30分よりも60分のデータを使用することが望ましいと思われる。また，ガソリンなどのように混合成分から成る物質の急性毒性影響は，それらに含まれている単成分の特徴を強く反映していることが本研究によって示唆された。

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