Distribution of Dearomatised White Spirit in Brain, Blood, and Fat Tissue after Repeated Exposure of Rats

Abstract

Petroleum products with low content of aromatics have been increasingly used during the past years. This study investigates tissue disposition of dearomatised white spirit. In addition, brain neurotransmitter concentrations were measured. Male rats were exposed by inhalation to 0, 400 (2.29 mg/1), or 800 p.p.m. (4.58 mg/l) of dearomatised white spirit, 6 hr/day, 5 days/week up to 3 weeks. Five rats from each group were sacrificed immediately after the exposure for 1, 2, or 3 weeks and 2, 4, 6, or 24 hr after the end of 3 weeks' exposure. After 3 weeks of exposure the concentration of total white spirit was 1.5 and 5.6 mg/kg in blood; 7.1 and 17.1 mg/kg in brain; 432 and 1452 mg/kg in fat tissue at the exposure levels of 400 and 800 p.p.m., respectively. The concentrations of n-nonane, n-decane, n-undecane, and total white spirit in blood and brain were not affected by the duration of exposure. Two hours after the end of exposure the n-decane concentration decreased to about 25% in blood and 50% in brain. A similar pattern of elimination was also observed for n-nonane, n-undecane and total white spirit in blood and brain. In fat tissue the concentrations of n-nonane, n-decane, n-undecane, and total white spirit increased during the 3 weeks of exposure. The time to reach steady-state concentrations is longer than 3 weeks. After the 3 weeks' exposure the fat tissue concentration of n-nonane, n-decane, n-undecane, and total white spirit decreased very slowly compared with the rate of decrease in blood and brain suggesting that long-lasting redistribution from fat to brain may occur. One week of exposure at 800 p.p.m. caused a statistically significant increase in whole brain dopamine concentration while the noradrenaline concentration was unaffected. Exposure at both exposure levels for 1 week caused a statistically significantly decreased concentration of 5-hydroxytryptamine in whole brain. The reduction was related to the exposure concentration. These changes in neurotransmitter concentrations were normalised after 2 and 3 weeks' exposure. In conclusion, after 3 weeks of exposure the fat:brain:blood concentration coefficients for total white spirit were approximately 250:3:1, and redistribution from fat to brain is possible. As total white spirit behaved similarly to the n-alkanes in blood, brain, and fat tissue, we suggest that the non-n-alkane white spirit components possess toxicokinetic properties similar to the n-alkanes.

Richtwerte für die Innenraumluft: Aromatenarme Kohlenwasserstoffgemische (C9–C14)

“…Bei spiels wei se las sen sich in ei nem entaro ma ti sier tem Test benzin über 150 Ver bin dun gen nach wei sen [4]; das Stod dard sol vent IIC ent hält über 80 Ver bin dun gen mit ei nem An teil über 0,1 und 30 Ver bin dun gen mit ei nem Anteil über 1 der Ge samt men ge [5].…”

“…Pha se nicht be stimmt wer den. Die Ki ne tik des un ter such ten Testben zins spie gel te sich auch in den zu sätz-lich un ter such ten Leit ver bin dun gen n-Nonan, n-De can und n-Un de can wi der [4]. Die im entaro ma ti sier ten KWL ent hal tenen ver zweig ten Al ka ne ver hiel ten sich toxi ko ki ne tisch wie die n-Al ka ne [4,22,23,24].…”

“…Die Ki ne tik des un ter such ten Testben zins spie gel te sich auch in den zu sätz-lich un ter such ten Leit ver bin dun gen n-Nonan, n-De can und n-Un de can wi der [4]. Die im entaro ma ti sier ten KWL ent hal tenen ver zweig ten Al ka ne ver hiel ten sich toxi ko ki ne tisch wie die n-Al ka ne [4,22,23,24]. Nach 12-stün di ger In ha la ti on ei nes Ge mi sches aus den 3 C 9 -Ver bin dun gen nNo nan, Tri me thyl cy clo he x an und Tri methyl ben zol ließ sich hin sicht lich Auf nahme und Ver tei lung kei ner lei Wech sel wirkung er ken nen [25].…”

“…In meh re ren tier ex pe ri men tel len Un tersu chun gen an er wach se nen Wi star-Rat ten zeig ten sich bei ei ner 6-stün di gen Ex po si tion pro Tag über 21 Tage ge gen über 0, 2300 oder 4600 mg entaro ma ti sier tem Test benzin 6 /m 3 in der ers ten Ex po si ti ons wo che deut li che Reiz wir kun gen an den Schleimhäu ten mit Trä nen fluss und Na sen blu ten, die mit fort schrei ten der Ex po si ti ons dau er all mäh lich zu rück gin gen [4,35,36,37].…”

“…Der No rad rena lin-Spie gel im Ge hirn blieb un ver än dert. In bei den expo nier ten Grup pen fiel in der ers ten Ex posi ti ons wo che eine se die ren de Wir kung auf, die mit fort schrei ten der Ex po si ti on zu rück-ging [4]. In den Hirn syn ap to so men nahm die Men ge an re ak ti ven Sau er stoffs pe zi es zu [28].…”