The Factors Of Nitrogen Pollution,Dietary Behavior And Other Comprehensive Factors Related To Liver Cancer In Chaoshan Area

BackgroundAs the sixth most common cancer worldwide,Liver Cancer(LC)is the most common primary cancer of the liver,which caused by a variety of causes.Liver cancer is also a common malignant tumor in China.In 2018,there were about 393,000 cases of liver cancer and 369,000 cases of death in China,accounting for 9.2% and 12.9% of all cases of malignant tumors in China,and 46.7% and 47.2% of all cases of malignant tumors in the world.The incidence and mortality of liver cancer are rank ahead in China.We considered that LC might be related to exposures to specific environment,dietary behavior and other factors because of the significant gender and regional differences in the incidence and mortality of liver cancer,in our country.At present,the research on the correlation between LC and natural environment,environmental pollution,social and economic conditions,dietary behavior and other comprehensive factors in Chaoshan area has not been seen.In order to understand the exposure status of certain factors and the frequency(incidence and mortality)of LC in different populations or regions,and then analyze the relationship between the exposure factors and LC,we designed this study.Based on the Chaoshan data in the national database of cancer prevention and control,environment,meteorology,industry and agriculture,and socio-economic and cultural,the methods of data mining and field questionnaire survey in the study were adopted to investigate the dietary behavior of people in Chaoshan area.And through the trend surface analysis and multi-factor model(linear,nonlinear),the study aimed to find the comprehensive related risk factors of liver cancer,to explore the relationship between geographical distribution of liver cancer and environmental and living exposure factors,and to verify the hypothesis of environmental factors for liver cancer in Chaoshan area.MethodsIn Haifeng,Lufeng,Jieyang,Shantou City,Chenghai,Chaozhou City,Raoping,Nan’ao a total of 8 areas,1-2 city / county senior middle schools were selected by using the convenience sampling method.The parents of the students in the middle school were taken as the research participants to investigate the demographic characteristics and dietary behaviors of each city /county.The data of LC mortality,environmental nitrogen pollution,agricultural production,climate and geography,social and economic conditions and other factors in Chaoshan county(city)were obtained from the public health science data center,the national agricultural science data center,the national population and health science data sharing service platform.Different modeling methods(Trend Surface Analysis,Structured Multiphase Regression Model,Factor Analysis-Logarithmic Regression Model and BP Neural Network Model)and data mining methods were used to analyze different types of data,to explore the related factors that may affect the mortality of LC among residents in multiple ways,and to evaluate the possible influence of various factors on the mortality rate of LC in Chaoshan area.The statistical analysis software used in this study are SPSS 25.0 and SAS 9.4.Results1.Environment,economy and residents’ dietary behavior in Chaoshan areaThe differences of socioeconomic status(population,population density,GDP,first output value per capita),land resources(per capita cultivated land,dry land ratio,vegetable land ratio),climatic and geographical factors(average altitude,annual rainfall,annual evaporation,aridity),environmental pollution factor(pig nitrogen load index,amount of pesticides per arable land,amount of nitrogen fertilizer per arable land,the amount of fertilizer per arable land)among 8counties(cities)in Chaoshan area are all statistically significant(all P < 0.05).The smoking rate(60.26%)and drinking rate(30.15%)in 8 counties(cities)of men are much higher than the smoking rate(3.06%)and drinking rate(3.21%)of women in Chaoshan area.The cumulative estimated smoking and alcohol consumption per capita of male residents in Nan’ao are higher in all age groups.In terms of diet,the higher intake frequency of pickles is Nan’ao;the higher intake frequency of salted fish is Lufeng,Haifeng and Nan’ao;the residents of Chenghai,Chaozhou,and Raoping areas often consume fish sauce,(30～years old)and(45～years old)age group residents often consume fish sauce;the highest intake frequency of vegetables,fruits,bean products is Lufeng(269.70 ± 54.46 days / year,213.73 ± 66.09 days / year,143.32 ± 61.90 days/ year);the highest consumption frequency of seafood is Nan’ao(21.31 ± 7.29 days / month;the highest frequency of meat consumption is Chaozhou(24.63 ± 6.35 days / month);Chaozhou and Lufeng residents’ egg intake frequency is higher;Shantou and Chaozhou residents’ milk intake frequency is higher and the difference is statistically significant(all P < 0.05).The regular tea consumption rate of male residents(74.48%)is higher than the rate of female tea-drinking(60.99%)in Chaoshan area,all three levels of LC-SMR have the highest proportions of "drinking kungfu tea" and "moderate concentration" of tea(all P < 0.05).2.Analysis of liver cancer-related factors in Chaoshan areaThe geographical distribution of mortality rate of LC is similar to the trend surface image of pig-nitrogen load index in Chaoshan area.There are 2 trends can be found: the first is a gradual decline from the inland areas,northeast of Guangdong(Nan’ao,Raoping)to the southeast of Guangdong(Haifeng,Lufeng),the second is a gradual decline along the coastline,from the east to the west of the Chaoshan area(male: rs=0.938;female: rs=0.931;all gender:rs=0.955,all P <0.05).In Structured Multiphase Regression Model and Factor Analysis-Logarithmic Regression Model,the standard coefficient of regression of pig nitrogen load index was the largest,followed by environmental pollution factor(F1),and the standard coefficient of regression of temperature factor(F2)was negative(the absolute value was larger than other variables and factors).We find that the main potential risk factors of LC death in Chaoshan area are cultivated land pollution factors(including pesticides per cultivated land,nitrogen fertilizers per cultivated land,chemical fertilizers per cultivated land),and pig nitrogen load index.The main potential protective factors of LC death in Chaoshan area are temperature factors(including annual ground temperature,annual 10 cm ground temperature,annual average temperature)and Plant-based food factors(fruit and vegetables).The BPNN Model finally screened 12 factors from 30 variables in total.The top six factors in the importance of normalization are: annual rainfall,pig nitrogen load index,annual average temperature,pesticides per cultivated land,nitrogen fertilizers per cultivated land,chemical fertilizers per cultivated land.We can see the significance of cultivated land pollution factors(especially nitrogen pollution factors)and geographical climate factors play an important role in the possible influencing factors of LC death.The prediction accuracy of LC-SMR by BPNN was 99.49%.ConclusionsAfter considering the combined effects of many factors,under certain environmental conditions,there has a positive correlation between nitrogen pollution from pig manure and LC mortality in Chaoshan area.The results support the hypothesis of the etiology of nitrogen cycle in liver cancer in Chaoshan area.