Study On The Risk Of Cardiovascular Diseases In Residents Drinking Desalinated Seawater

BackgroundWorld Health Organization(WHO)defines cardiovascular diseases(CVDs)as a group of cardiac and vascular diseases,which is the leading cause of death in the world.Data show that there are 17.7 million people died of CVDs in 2015,and mainly died of coronary heart disease and stroke.Heart attacks and strokes are generally considered to be a combination of smoking,unhealthy diet,obesity,lack of physical activity and abusing alcohol,hypertension and other risk factors[1].The water resources of China are severely depleted.Groundwater is seriously oversubscribed and surface water pollution is serious.To ensure safe and adequate water supply,we need to make comprehensive use of water resources.Desalination is one of the important drinking water resources,especially in coastal cities and some special circumstances.In a non-polluting environment,food and drinking water intake can be considered as the most important way for human body to expose to chemical substances.The physical and chemical properties and chemical components of desalinated seawater may be different from the surface water and underground water.Research focused on this field is very limited.Therefore,this study has practical value and certain theoretical significance.Desalinated seawater is different from traditional water sources,which is with low mineral content,poor water quality stability,and hardness often less than 75 mg/L.Water usually contributes a small part of the recommended daily intake of essential elements of the human body.And most of it is ingested from food.However,since ions in water are usually directly used by organisms,it is likely that drinking desalinated seawater for a long time may result in inadequate mineral deriving from water resources.The results of Zhang Yongli[2]and Fei Junliang[3]about desalinizated seawater and the health of residents show that people who drink desalinated seawater have higher prevalence of blood pressure,dyslipidemia and coronary heart disease than those who drink fresh water and mixed water sources(diluted desalinated seawater and fresh water).Yang Xiaoxiong[4]investigated the relationship between desalinated seawater and hyperlipidemia,and there is no statistical correlation between them.At present,the health effects on drinking desalinated seawater still need to explore further.This research field is located in the northern of East China Sea,which has small land area and lack of water resources.Due to lacking fresh water resources,the local residents rely heavily on desalinated seawater.In some townships,the consumption of domestic water almost dependent on desalinated water entirely.The investigation of desalinated seawater quality shows that desalinated seawater is a typical "soft water".The content of calcium and magnesium in water is often lower than that of traditional freshwater resources[5],and insufficient intake of calcium,magnesium and other minerals may be related to cardiovascular disease[6-8]Therefore,the study aims to know about the local prevalence of cardiovascular disease and analyze its possible risk factors,and to explore whether drinking desalinated seawater is a risk factor for the occurrence of cardiovascular disease among residents,and to explore other possible risk factors for the residents of the island.The research will provide theoretical basis,basic data and clues for the study on the relationship between residents' health and drinking desalinated seawater in China.ObjectivesTo understand the current status of desalinated seawater hygiene research in China,to understand the prevalence of cardiovascular disease among island residents and the local water quality hygiene situation.To explore the relationship between residents' cardiovascular disease and local residents' lives,behavioral habits,and drinking water exposure.To provide data support and theoretical basis for local cardiovascular disease prevention and policy intervention.MethodsThe status of hygiene management of desalinated seawater in China was analyzed by field surveys,expert discussions,and literature surveys.Through investigations,we obtained cardiovascular disease data about residents of an island county to analyze its epidemic characteristics.Local water supply sources,basic water quality,and domestic water were surveyed in each township in the county,and G townships that supply seawater desalinated water and H townships that supply fresh water were identified as two survey sites.We collected some of the water quality data and the residents' health checkups data from 2013 to 2016 as the retrospective baseline data.With nested case-control study,new cases of cardiovascular disease were included in the case group,with the same gender,age ± 2 years,and matched controls(1:1)during the same period.At the same time,the urine samples of the subjects were collected for measuring the concentration of calcium,magnesium and urinary creatinine content.The Epidata 3.1 was used for double-entry questionnaire,and SAS 9.3 for conditional logistic regression analysis.ResultsPart 1 Current situation of hygienic management of seawater desalination in ChinaThe desalinated seawater project for residents' domestic water accounts for 1/3 of the total scale.The main problems of water quality for desalinated seawater are low TDS,low mineral ion contents and hardness,and the hardness of desalinated seawater is generally in the range of 10?75 mg/L.In addition,there are problems concerning corrosion of the water transmission network,as well as imperfect health supervision,policies and regulations.The main health effects of desalinated seawater on human bodies include cancer,thyroid disease,and cardiovascular diseases.Part 2 The prevalence of cardiovascular diseases in the island countyFrom 2013 to 2016,the incidence of cardiovascular disease in the county showed an upward trend,and the mortality rate steadily decreased.The prevalence of cardiovascular diseases among people over 35 years old who participated in the health checkups in 2013 were related to age,(central)obesity,hyperglycemia,hypertension,physical exercise,desalinated drinking water and heart rate.Part 3 Nested case-control study on the risk of cardiovascular diseases in residents drinking desalinated seawaterThe results of data review and laboratory analysis showed that there were no significant differences between H townships and G townships except for the significant differences in water quality.The tap water hardness of H township is 140 mg/L,while it is lower than 5 mg/L in G townships.And there is no significant statistical difference for calcium and magnesium metabolism levels between two township residents(p>0.05).The nested case-control study showed that the cumulative incidence of cardiovascular disease in the two townships for the period from 2013 to 2016 was 18.83‰,and the main risk factors for residents'cardiovascular disease were obesity(OR=5.38,95%CI=1.05?27.45),lack of physical activity(OR=0.35,95%CI-=0.16?0.75),hypertension(OR=3.61,95%CI=1.58?8.25),alcohol drinking(OR=2.57,95%CI=1.02?6.47),and irritability(OR=4.30,95%CI=1.93-9.60).And drinking desalinated seawater has shown no effect on the occurrence of cardiovascular disease in residents(OR=0.94,95%CI=0.49?1.83).ConclusionChina's desalinated seawater needs improvment in many aspects such as water quality,management and policies.The special geographical environment of the island and the diet habits of the island residents may lead to a special epidemic of cardiovascular disease in the island residents.Through the ecological study,the second part of the article initially explored the possible association between the occurrence of cardiovascular diseases in local residents and drinking desalinated seawater.The third part of the nested case-control study further test the relevant hypotheses and found that the possible risk factors for cardiovascular disease in local residents are obesity,lack of physical activity,hypertension,alcohol drinking,and irritability.The study did not find out that drinking desalinated seawater can increase the risk of cardiovascular diseases in the local residents.