| Vanadium is one of the main chemical elements of fossil fuel and is abundant in petroleum and coal. In recent years along with China's fast growing economy, consumption of energy products increases quickly. Vanadium enters into the atmosphere with gas produced by the burning of much petroleum and coal, thus renders all people exposed in increasing vanadium burden. At the same time, vanadium is widely used in petroleum chemical engineering, steel smelting, welding and catalyst...etc. as an important chemical element. Therefore the number of occupational people who are exposed to vanadium compound is quite huge.The nervous system is the most sensitive to poisonous or hazardous factors and usually is the first organ to be injured when one is exposed to those factors, causing the body's behavior change in early days. Many researches concerning the toxicity of vanadium compound have no involved this aspect, and there is especially lack of epidemiological study. This research aims to evaluate whether vanadium compound has toxicity to neurobehavioral effect and elaborate its effect characteristic. The thesis is divided into three parts: test on neurobehavioral function among people; evaluation on neurobehavioral function among rats; pathological diagnosis. The following is the results of these three parts. 1. Vanadium compound's influence on neurobehavioral function among workers exposed to vanadiumWe adopted the NCTB (Neurobehavioral Core Test Battery) recommended by the World Health Organization and tested 193 workers exposed to vanadium (exposed group) and 273 workers unexposed (control group). There was no statistically significant difference between two groups in gender distribution. Educational background in the control group was higher than that in the exposed group (P<0.05). For the average age, there is no significant differences between two groups, respectively 35.9 + 6.7 in exposed group and 34.5 + 5.6 in control group. Also there is no significant differences for work duation, respectively 16.6 + 6.8 in exposed group and 14.3 + 6.2 in control group. Vanadium dust density in the exposed group's workshops exceeded the occupational exposure limit for nearly 20 times in general, with some differences among each workshop. There was no vanadium dust tested in the control group's workshops. Blood vanadium density test showed that almost all blood vanadium densities of exposed workers exceeded occupational exposure limit about 10-20 times averagely.After adjusting mixing factors, the NCTB emotion test results showed that workers exposed to vanadium got higher scores than control group workers in "Tension-anxiety", "Depress-dejection", "Anger-hostility", "Fatigue-inertia", "Confusion-bewilderment", while they got lower scores in "Vigor-activity", with all differences statistically significant (P<0.05). The results indicated that the vanadium compound increased the negative motion (including anxiety, depression, anger, fatigue, confusion) in workers exposed to vanadium, and decreased the positive motion (activity). After splitting the data according to gender, the results displayed that vanadium compound increased negative motion and decreased positive motion in male workers exposed to vanadium, while in female it only decreased positive motion. After splitting the data according to work duration, the results displayed that among workers less than 10 years, there was no statistically significant difference; among those between 10 and 20 years, vanadium compound increased negative motion and decreased positive motion in exposed group and the differences were statistically significant (P<0.05); among those over 20 years, vanadium compound increased negative motion in exposed group and the difference was statistically significant (P<0.05) while there was no statistically significant difference in scores of negative emotion between two groups.As to neurobehavioral, there were no statistically significant differences in simple reaction time between two groups (P>0.05); As to digit span, the exposed group got a higher scores in forward and a lower scores in backword with no statistically significant differences (P>0.05); As to Santa Ana, the exposed group got a lower scores either with habitual or non-habitual hand and the difference was statistically significant (P<0.05); as for digit symbol and Benton visual retention, the exposed group got lower scores and the differences were statistically significant (P<0.05); as to pursuit aiming, the exposed group got less right points , more wrong points as well as a lower exactness rate than the control group and the differences were statistically significant (P<0.05). After splitting the data according to gender, we found that male workers were more sensitive than females, as the differences were statistically significant (P<0.05) in indexes of Santa Ana, digit symbol, Benton visual retention, pursuit aiming etc. in male workers from two groups, while there was no statistically significant differences in female workers. After splitting the data according to work duration, we found that most indexes had statistically significant differences in workers between 10 and 19 years. The results indicated that the sensitivity of different nerve behavior functions to vanadium compound varied, and was influenced by workers' age. The more sensitive indexes were, the earlier these functions change appeared. Yet along with the growth of age, the harm effect of vanadium compound decreased because of the aging effect interference.We extracted 7 main compositions using the Main Composition Analysis method. Its analytical results were in accordance with the multivariate analysis results of nerve behavior function.2. Sodium metavanadate's influence upon the neurobehavioral function of ratsThe exposed rats were divided into three dose groups: high dose, medium dose and low dose. At the same time we adopted a positive control group (manganese chloride) and blank control group (distilled water). All rats were made by intragastric administration for 30 days. Then all rats finished three tests, including Open Field Test, Rotarod and Maze experiment, mainly reflecting cognition ability, sport vitality and sport coordinate ability. Totally we did tests for 4 times, respectively on the 0 days (before stomach infusion), 30 days (just after stomach infusion), 40 days (10 days after stomach infusion) and 50 days (0 days after stomach infusion).Experiments indicated that sodium metavanadate showed a toxicity to gastrointestinal and respiratory, which was reflected as follows:â‘ Only 65 rats survived, and 25 rats died. The main reasons for death might the two kinds of toxicity mentioned above;â‘¡Rats in sodium metavanadate group (especially in the high dose group) had lower weight than those in blank control group.Results of the neurobehavioral function evaluation showed:â‘ As to the rats exposed to sodium metavanadate, the higher dose they were exposed to, the less lattices they could walk through. But there were not so much differences in the times for straighten;â‘¡There were not too many differences between results of rats in the low dose group and that of rats in the blank control group, while results of rats in the high dose group was similar to that of rats in the positive control group. This results indicted that sodium metavanadate could decrease the rats's coordinate ability ?When it came to memory, there was not much difference in the time it took rats to arrive at the end between each exposed group and their corresponding control group. As to times of mistakes, it was higher in each exposed group than that in their corresponding control group. The times of mistakes in medium and high dose groups were close to that in manganese chloride groups.3. Pathology test to rat brain tissue exposed to sodium metavanadateOn the 30th days after intragastric administration, 30 rats were chosed randomly with each 10 from medium dose group, low dose group, positive control group and blank control group respectively as samples for pathologic section. All the 4 rats survived in the high dose group were killed for pathologic section. The position is median sagittal plane of brain, including cerebrum, cerebellum and hippocampus. We mainly concerned whether there were any pathologic changes in these three parts.The pathologic section results showed that there were no significant pathological changes in the cerebrum, cerebellum, hippocampus and brain stem in all rats. Though there are some changes found in section, such as hemorrhage and thickening in meninges, proliferation of gliocyte cell in hypoependyma, proliferation of horizontal cell in brain mantle, cyst, etc. No inflammation was found nearby pathologic parts, and the difference wasn't statistically significant in groups. As a result, we thought sodium metavanadate wouldn't cause pathological changes in the brain, cerebellums and brain stems.In general, as the vanadium burden keeps rising in our daily environment and the number of occupational workers exposed to vanadium is quite huge, it is practically meaningful to evaluate whether vanadium compound has toxicity to neurobehavioral function and its effect characteristics. This thesis studied the nerve toxicity comprehensively and systematically. It explored the neurobehavioral changes in occupational group and accumulated epidemiological data. After a comprehensive evaluation on vanadium compound's neurobehavioral toxicity (including neurobehavioral changes among people, behavior changes of rats and brain pathology test of rat), we concluded that vanadium compound had neurobehavioral toxicity, and the effect characteristics were relative with gender and time of exposure. The specific effect characteristics included:â‘ vanadium compound can increase the negative motion (including anxiety, depression, anger, fatigue, confusion) and decrease the positive motion (activity) in workers exposed to vanadium.â‘¡both animal experiment and epidemiological investigation indicated that vanadium compound can lower the coordination ability;â‘¢it is not sure that vanadium compound might decrease short-term memory and further research is needed.
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