The Research On An Integrated Fuzzy Model For Assessment Of Water Environmental Health Risk Based On Interval Numbers

Uncertainties is found in the process of water environmental health risk assessment. The urgent affair is how to deal with the uncertainties in the assessment process to make sure the result of the assessment is more exact. In this study, the interval numbers and the fuzzy theory were adopted to reduce the uncertainties in the assessment process. In the tradition assessment process, the average concentration of the contamination was used. However, the concentrations of contaminations in the river vary with time. Therefore, the usage of average concentration of the contamination to assessment the health risk may ignored the mutative characteristic of the concentration in a certain extent, and resulted in the uncertainties in the assessment process. In the present study, the interval numbers were used to express the concentration of the contaminations, the maximum and the minimum of which are the highist and the lowest value of the monitoring value in the whole year. The interval number is not a number but a range, which include more information. Using nterval number can reduce the uncertainties in the assessment process comparing to use the average concertainty.Evaluation standard is the importance basis in the health risk assessment. Recently, the frequently adoptive evaluation standards are from United States Environmental Protection Agency and the International Commission on Radiological Protection. The EPA take for the 10-4 level as the safe level, while the ICRI think the risk must be less than 10-5. Distinction of the two ecaluation standards is very distinctive, and consequently, it's hard to choose a comparatively reasonable evaluation standard to evaluation the health risk. In the present study, we adopt the fuzzy theory to describe the risk evaluation standard. The fuzzy theory is used to fix quantify of those factors which is difficulty to make clear the boundary and measure. The fuzzy theory also is a integrate evaluation method in this study. The experts consultation method based on information was used to establish the evaluation standard system. In the system, the risk were classified as six levels of"low","low-medium","medium","medium-high","high"and"very-high", following: C1={â… /low}; C2={â…¡/low-medium}; C3={â…¢/ medium}; C4={â…£/medium-high}; C5={â…¤/high}; C6={â…¥/very-high}.On the basis of the interval numbers and fuzzy theory, an integrated fuzzy model for water environmental health risk assessment was developed. The model was used to assess the health risk for the Xiangjiang River of the Changsha-Zhuzhou-Xiangtan Reach from 2005 to 2007.It is shown by this research that the integrated fuzzy model for water environmental health risk assessment can reduce the uncertainty in the assessment process in a certain extent. Compared with the confirm assessment model, the assessment conclusion of the integrated fuzzy model is more all-around and reasonable to reflect the true condition of the water environmental health risk level.