Water Quality Monitoring And Health Survey In Typical Area Using Desalinated Seawater As Drinking Water

BackgroundWith the global population growth, climate change, environmental pollution and many other factors, shortage of freshwater resources has become one of the major issues in the world. Many countries turned to the sea to seek a possible way of getting water. Desalination made it practicable. Desalination is trend to become an important government advocates and strategies to develop new water sources. China is one of the world’s most water-scarce countries.400 out of 669 cities face water shortage and 110 face serious water shortages. Lack of freshwater resources has become a serious constraint to social progress and development in China. Desalination has great strategic significance.It is still unclear about whether desalinated seawater leads to health problems. There are doubts about it among average people. It’s necessary to conduct hygiene evaluation on desalinated seawater and health survey in demonstrative district. A certain county, located in the east China sea, applied desalination in municipal water supply from 1997. It had become an important water source, making up more than 70% of water supply in dry season,60% in the whole year. Water quality monitoring and health survey in a typical district using desalinated seawater as drinking water, would help us to figure out the water quality and the health effects of desalinated seawater.ObjectivesTo investigate the qualities of the product water and tap water of desalination; to analyze the characteristics of death in this county; to explore prevalent state of chronic diseases and risk factors; to explore the health effects of desalination and to try to come up with an evaluation system on desalinated seawater quality.MethodsWater quality monitoring was conducted in the county from May 2015 to April 2016.5 surveillance sites of product water and 23 surveillance sites of tap water were set. Monthly water samples were collect and detected. Detection was carried out in accordance with Drinking Water Sanitation Standardized Testing Method(GB/T5750-2006). Evaluation of water test results was according to Standard for drinking water quality(GB5749-2006). A cross sectional study was carried out in May 2015 to investigated a total of 2219 people aged above 20 in the county by questionnaire for information about the prevalence rate and influence factor of 4 kinds of chronic disease. The data was analyzed by chi-square test and multivariate logistic regressions. Local historical data, such as monitoring datas on water quality and datas of the death-surveillance were collected for analysis.Results1. The quality of desalinated seawaterMicroorganism could be intercepted in desalination plants effectively. Desalinated seawater had good sensuous properties. Each general chemical index met the requirement of sanitation standards. Excessive levels of boron were widespread in both product water and tap water of desalinated seawater. The boron level was in the range of 0.68-1.46mg/L and 0.62-1.26mg/L, respectively. The other 15 toxicology indexes all met the requirement of sanitation standards.2. Residents’health statusDuring 2008-2012 in the county the crude mortality was 673.26/105, and the age-standardized rate was 481.55/105. The five major causes of death were malignant neoplasms, cerebrovascular disease, cardiovascular disease, respiratory disease, poisonings and injuries. Then crude mortality of cardiovascular disease(CVD) was 125.23/105, the age-standardized rate was 86.03/105. There was no significant change in the mortality of CVD in the county during 2008-2012. The age-standardized mortality of CVD was lower compared with nation level in 2012.According to the results of field epidemiological investigation held in 2015, the morbidity rate of hypertension was 16.31%(the standardized rate was 13.11%); the morbidity rate of hyperlipidemia was 3.56%(the standardized rate was 3.08%); the morbidity rate of heart disease was 4.91%(the standardized rate was 4.19%); the morbidity rate of diabetes was 2.79% (the standardized rate was 2.32%). Compare with the morbidity rate of national and provincial level, the 4 kinds of diseases didn’t show an obvious increasing trend. Risk factors relative to hypertension included age, BMI, diabetes, hyperlipidemia. Risk factors relative to hyperlipidemia included smoking, average monthly income, BMI, family history, hypertension, diabetes. Risk factors relative to heart disease included age, family history, BMI, excessive drinking, hypertension and hyperlipidemia.Conclusion(1) Evaluated by Standard for drinking water quality(GB5749-2006), desalinated seawater basically meets the requirement of sanitation standards. The unconventional water treatment processes gives desalinated seawater the qualities, such as high boron content and low hardness. The evaluation system of safety and hygiene of drinking water must be made.(2) The results of the cross-sectional study showed that the prevalence rates of hypertension, hyperlipidemia, heart disease and diabetes in 2015 were lower than national and provincial level. It calls for further cohort studies to track health conditions of people in those areas and evaluate the safety of desalinated seawater.