The Experiment Study On Mechanism Of The Central Nervous System Injury Of Mice Caused By Bitumen Fume

AIM: Asphalt or Bitumen Fumes is a special complex air pollutant producedin road paving ,aluminum industry and waterproofing and other jobs entailing exposure to bitumen fume.The fume consist of liquid hydrocarbon particles and gaseous hydrocarbon derivatives, is a mixture of paraffinic and polycyclic aromatic hydrocarbons ( PAH) and heteroatomic compounds containing sufur, nitrogen and oxygen.More than 10 chemical materials of the fume are carcinogen to humans.The workers exposed to bitumen fume have potential health problems. The A great deal of study expresses the damage of the lung and the skins of the workers exposed to bitumen fume are more familiar, but the damage of the nervous system is less. In this topic, we will observe and study the pathological changes of the neuron cell , the content of neurotransm itter including dopamine(DA), norepinephrine(NE) and 5-hydroxyptamine(5-HT) and apoptosis ratio in brain cells in bitumen fume-treated mice brain tissue and investigate the mechanism of the damage on nerve system.METHODS:In this subacute toxicity study,200 Kunming mice were providedby Laboratory Animal Center of Lanzhou University .They were 4 weeks old and half were male .All the mice were randomly divided into experimental and control groups.Each group had 40 mice .The experimental groups were exposed to bitumen fumes (average 41mg/m~3, 82mg/m~3 and 165mg/m~3) by inhalation in a sealed vessel for 2 hours/day, 6days every week. One third of the mice were executed after inhale bitumen fume for 2w, 4w and 8w .The weight of the mice and were measured once a week. Apoptosis ratio of cells in brain tissue were detected by flow cytometry.Morphologic features of brain tissue were observed by optical microscopy and electronic microscopy. The content of DA,NE and 5-HT were measured by the fluorescence.RESULTS:1.Effect on growth: Bitumen fume has negative effect on the growth of the animals. The body weight gains of the animals in bitumen fume-treated were lower than in the control groups, significantly on the high treated group in early time.The weight of every treated groups is lower significantly than normal control group in lw,2wand 3w.2.Effect on: The Apoptosis ratio is not significant in erery bitumen fume- treated group in Second acute treated model and every time segment.But in the middle treated group and the high treated group, the apoptosis ratio is higher significantly than the rest groups in acute treated model.3.Effect on neurotransm itter: The bitumn fume could result in the decrease of the contents of in all groups. All the changes were correlated with the exposure level and the tim of action.4.Effect on brain tissue morphology: The main mitochondria changes of bitumen fume-treated groups were the mitochondria swollen, chromatin margination ,pyknosis and apoptosis in neuro cells.No Obvious changes in every group Observed by optical microscopy.CONCLUSIONS: Bitumen fume can cause negative effect on the micegrowth and development .A long-time exposure of bitumen fume can cause the decrease in content of DA,NE and 5-HT and mitochondria swollen, chromatin margination ,pyknosis apoptosis in neuron cell. And acute exposure bitumen fume can cause damage neuron cell seriously.