A Follow-up Study On Skin Injuries Of Local Residents In An Arsenic Exposed Area By Arsenic Removal Actions In Drinking Water

Objective:Skin lesion is the most significant clinical symptoms of arsenic poisoning,but there is no consistent view on the out of skin lesion after water arsenic reduction,and epidemiological evidences in this field are not sufficient.So we should carry out more investigation and research.Our research team condectd a follow-up survey by gangfangying village to explore the prognosis of the skin lesion and impact of various factors on it.Methods:In July 1999,our team conducted a survey of gangfangying village,an endemic arsenic exposure area in Inner Mongolia,with a total of 99 people.We through questionnaire asks and measure to collect the general characteristics of the local residents such as gender,age,height,weight,and take blood samples and urine samples for the arsenic content determination.At the same time,we take photos and evaluate the level of skin lesion through People’s Republic of China health industry standards《WS/T211—2015》by two doctors.After that our team go to the village many times to continue the follow-up investigation after two decades.According to the changes of skin lesion,the follow-up subjects were divided into remission,invariance and deterioration.Use the data to establish a database and make statistical analysis through SPSS 24.0 software.The continuous data satisfying normal distribution are described by means and standard deviation,and use one-way ANOVA analysis to determine the different groups.For non-normal distribution data,such as arsenic content in blood and urine use the median and interquartile interval to express,and used to determine the difference by non-parameter test.Through the classification variables to describe frequency(rate),and used to test the difference by chi-square test or Fisher’s exact probability method,p<0.05 was statistically significant.Results:1.Generally residents before the water improvement:The average concentration of arsenic exposure in drinking water was 202.73μg/L.There were no significant differences in the distribution of age,BMI,gender,smoking and drinking under different levels of arsenic exposure(≥100μg/L,10-100μg/L,≤10μg/L)(p<0.05).The contents of different forms of arsenic(iAs,MMA,DMA)and total arsenic(tAs)in blood and urine were different under different arsenic exposure levels of drinking water,and the difference was statistically significant.However,the difference of PMI and SMI in blood and urine were not statistically significant(p>0.05).The higher the exposure concentration of arsenic in water,the higher the proportion of skin lesion level,the proportion and severity of male patients were higher than those of females,and the above differences were more severe(p<0.001).The difference was statistically significant(p<0.05).2.Evaluation of the effect of water improvement:The urine arsenic level of the residents decreased significantly half a year after the water improvement,but the urine arsenic level of the villagers who had drunk water≥100μg/L group was still significantly higher than that of the arsenic concentration≤10μg/L group,and the level of 8-OHdG in each group decreased significantly one year after the water improvement,and the difference was statistically significant(p<0.05).3.The changes of skin injury at different time points after water improvement:The change of local residents’skin lesion one year after water improvement is related to the clinical division of the skin before the water improvement,and the differences were statistically significant(c~2=28.432,p<0.001).After one year,residents who have had mild skin lesion or above may be relieved.Most of the residents without skin lesion remain unchanged,but some of the them appear the skin lesion.The change in skin lesion of local residents in the five years after water improvement was consistent with the one year after water improvement,and the differences were statistically significant(c~2=12.871,p<0.05).In the eleven years after water improvement,all the residents whose skin lesion level was relieved were moderate,and among those who remained unchanged,the proportion of without skin lesion was still the largest,followed by moderate and severe,and the worsened residents were suspicious and severe.However,the change of skin lesion regardless of the clinical division of the skin lesion before water improvement(c~2=8.691,p=0.096).The the change of skin lesion after 17-20 years regardless of the clinical division of the skin lesion before water improvement(c~2=7.344,p=0.217).4.The skin lesion of residents with low arsenic exposure is more likely to remain unchanged,while the skin lesion of residents with high arsenic exposure is easier to alleviate,but the different is not statistically significant(c~2=5.435,p=0.059).Skin lesion in male patients is more easily relieved,and female is easily to control,but skin lesion in male is also more likely to worsen than women,the different is statistically significant(c~2=9.486,p=0.009)..Residents with low levels of urinary arsenic are more likely to be controlled,and residents with high levels of urinary arsenic are more likely to worsen,and the different is statistically significant(c~2=10.576,p=0.003).Conclusion:1.Arsenic removal by water treatment can effectively reduce urinary arsenic level and oxidative damage in arsenic exposed population.2.Different Skin lesions still appear after removing arsenic from water.The prognosis of arsenic-induced skin lesions may be related to the skin lesions before water treatment.3.Gender and urinary arsenic levels may have certain influence on the outcome of arsenic-induced skin lesion.