| Part1: Effect of MMT-containing gasoline on plasma oxidative stress andHsp70among Gas station workersObjective To investigate the effect of MMT-containing gasoline on plasmaoxidative stress and Hsp70levels among gas station workers, and explore theearly sensitive indicators of health response among gas station workers.Methods A cross-sectional study was conducted. All subjects were selectedfrom9gas stations of four areas in Nanning, Guangxi. The gasoline operatorswere selected as the exposure group, and the gas station executives wereselected as the control group. A structured questionnaire was used to collect dataon demographic information, drinking and smoking habit, occupational history,as well as medication history. The manganese cumulative exposure index andthe mixed benzene exposure index were calculated. Plasma oxidative stress andHsp70levels were determined by ELISA in all the subjects. Simultaneously, theambient concentrations of manganese, BTEX were monitored in the work placesof gas station workers.Results:1. A total of144gas station workers were recruited into this study.48gas station executives were selected as the control group.13of them were male,35were female, the age ranged from from23to47years old, and the mean age ofthe workers was (33.0±5.9) years, the length of service ranged from1.7to21.7years, and the mean of the length of service was (9.8±5.9) years.96gasolinepipeline staffs were selected as the exposure group.32of them were male,64were female, the age ranged from from20to54years old, and the mean age was(33.8±7.2) years, the length of service ranged from1.0to13.7years, and themean of the length of service was (7.7±4.2) years. There were significantdifference in education and length of service between the two groups (P<0.05),while There were no significant difference in gender, age, nationality, marital,and drinking and smoking rate between the two groups (P>0.05).2. A total of86air manganese samples and36air BTEX samples weretaken from the sampling sites. The qualified rate was100%. At refueling area, the time weighted average concentration of manganese ranged from6.44to127.34μg/m3, which was higher than that of (3.16~7.22μg/m3) in the office area.Both of them were lower than the occupational exposure limit, which was150μg/m3. At refueling area, the air concentrations of benzene, toluene,ethylbenzene, and xylene ranged in (19.86~202.42)μg/m3,(77.09~886.53)μg/m3,(7.59~102.85)μg/m3, and (36.21~521.57)μg/m3, respectively. While in the officearea, the air concentrations of benzene, toluene, ethylbenzene, and xyleneranged in (2.31~29.36)μg/m3,(2.32~177.86)μg/m3,(1.26~45.95)g/m3, and（4.02~182.57） μg/m3, respectively. All of them were lower than theoccupational exposure limit.3. The activities of SOD and GSH-Px in exposed group were (39.18±6.05)U/ml and (186.07±15.63) U, which significantly lower than those of the controlgroup[(52.84±3.87)U/ml and (194.38±10.42)U, respectively], all p<0.05. These plasma indices had a significantly decreasing trend with the extending length ofservice, elevation of manganese and mixed benzene exposure level. The level ofMDA in exposed group was (1.68±0.52) nmol/ml, which was significantlyhigher than that of the control group[(1.68±0.52) nmol/ml](p<0.05). The levelof MDA had a significantly increasing trend with the extending length of service,elevation of manganese and mixed benzene exposure level.4. Plasma Hsp70levels in exposure group was (2.77±0.64)ng/ml, whichwas significantly higher than that of the control group[2.31±0.87(ng/ml)](P<0.05). After stratification by length of service, among the gas station workerswhose length of service were longer than10years, plasma Hsp70levels was(3.05±0.66)ng/ml, higher than that in the control group[2.38±0.90(ng/ml)](P<0.05). Plasma Hsp70levels had a significantly increasing trend with theextending length of service, elevation of manganese and mixed benzeneexposure level. Pearson correlation analysis showed that there was negativerelatioship between plasma Hsp70level and the activities of SOD(r=-0.305,p=0.003), as well as the activities of GSH-Px(r=-0.302, p=0.003) in theexposure group(p<0.05). While a positive correlation was found between plasmaHsp70levels and plasma MDA levels(r=0.653, p=0.000) in the exposure group.Conclusion:1. MMT-containing gasoline may reduce antioxidant ability of body andincrease lipid peroxidation levels among gas station workers. Moreover, theactivities of SOD and GSH-Px have a significantly decreasing trend with theextending length of service, elevation of manganese and mixed benzeneexposure level. The level of MDA has a significantly increasing trend with theextending length of service, elevation of manganese and mixed benzeneexposure level. It suggests that the plasma SOD, GSH-Px and MDA may be valuable in the early effective biomarkers of oxidative damage among gasstation workers.2. MMT-containing gasoline may increase plasma Hsp70levels, which hasa significantly increasing trend with the extending length of service. Hsp70maybe a sensitive biomaker of MMT-containing gasoline exposure．Part2: Effect of MMT-containing gasoline on cognitive function among gasstation workersObjective To investigate the the effect of MMT-containing gasoline oncognitive function among gas station workers, analyse the relationship betweenHsp70, oxidative stress and cognitive function impairment.Methods The Montreal Cognitive Assessment(MoCA) test was applied toassess cognitive function among all subjects in part1. The relationship betweencognitive function and Hsp70, oxidative stress were analysed.Results:1. The abstract ability scores, memory scores and MoCA scores in exposuregroup were (0.90±0.07),(2.75±0.14) and (23.08±0.28), which were significantlylower than those in the control group(1.29±0.11),(3.30±0.21) and (24.37±0.41),respectively. After stratification by gender, among the female subjects, thememory scores, abstract ability scores and MoCA scores in exposure group were(0.81±0.10),(2.43±0.21) and (22.70±0.41), which were significantly lower thanthose in the control group(3.24±0.35),(1.36±0.14) and (24.58±0.57),respectively. After stratification by length of service, among the gas stationworkers whose length of service were longer than10years, the abstract abilityscores, memory scores and MoCA scores in exposed group were (0.88±0.11), (2.40±0.20) and (22.62±0.42), which were significantly lower than those in thecontrol group(1.40±0.15),(3.65±0.27) and (24.52±0.59), respectively. Partialcorrelation analysis showed that there was a negative correlation betweenmanganese exposure levels and memory scores(r=-0.201, p=0.012), as well asMoCA total scores(r=-0.185, p=0.021), and there was a negative correlationbetween mixed benzene exposure levels and memory scores(r=-0.196, p=0.016),as well as MoCA total scores(r=-0.220, p=0.006).2. There was a negative correlation between plasma Hsp70levels andMoCA total scores among the exposed group (r=-0.477, P=0.019).Conclusion:1. MMT-containing gasoline may impair cognitive gas station workers’ function.The abstract ability scores, memory scores and MoCA total scores wereinversely associated with manganese and mixed benzene exposure levels.2. There was a negative correlation between plasma Hsp70levels andMoCA total scores, the increase of plasma Hsp70level may be associated withlipid peroxidation which was induced to preotcet nerve cell.The mechanism ofcombined neurotoxicity of manganese and BTEX could be related to Hsp70. |
