ABSTRACT
Objective To learn the exposure levels and health hazards of long-term exposure to hexavalent chromium (Cr6+) through drinking water in a west county,and to provide a scientific basis for making preventive measures.Methods Five water points were selected to test the Cr6+ concentration of drinking water in the county in 2015,data of 3 water points with water Cr6+ concentrations exceeded the standard (Cr6+ ＞ 0.05 mg/L) were selected from 12 drinking water points in some west counties in the recent six years (2009-2014) as the exposed group,2water points that drinking water Cr6+ concentrations not exceeded the standard (Cr6+ ≤0.05 mg/L) in the county and adjacent to the exposed group were selected as the control group.Sixty villagers were selected as the investigation objects in each water point to conduct internal medicine,ears,nose,throat (ENT),dermatology and health examination,urinary chromium content,routine blood and urine test were done.Determination of hexavalent chromium concentration in drinking water was done according to The Drinking Water Standard Examination Method 1,5-diphenylcarbazide Spectrophotometry (GB/T 5750-2006);routine urine was tested using the 10 urine analyzer test;urinary chromium was tested using graphite furnace atomic absorption spectrometer;routine blood five classification was tested using automatic blood analyzer;determination of drinking water hexavalent chromium concentration was done according to The Hygienic Standard for Drinking Water (GB 5749-2006).Higher than 0.05 mg/L was judged as exceeded the standard;physical examination was done according to The Diagnostic Criteria of Occupational Chromium Nasal Disease (GB Z12-2002) and The Diagnostic Standard of Occupational Contact Dermatitis (GB Z20-2002).Results There were 184 and 109 people in the exposed group and the control group,respectively.The average concentration of Cr6+ exceeding the standard ratio was 2.82-3.22 in drinking water,the nasal septum nucosa perforation,skin erythema edema,skin ulcers were 4.9％ (9/184),4.3％ (8/184) and 4.3％ (8/184) in the exposed group,and the urinary chromium level (0.31 μg/L) in the exposed group was significantly higher than that of the control group (0.27 μg/L,Z =-4.078,P ＜ 0.05).Routine blood test result of mean corpuscular haemaglobin (MCH) was (29.56 ± 2.07) pg,platelet counts (PLT) was (222.38 ± 47.53) × 109/L and plateletcrit (PCT) was (0.25 ± 0.05)％ in the exposed group,it was all higher than those of the control group [(29.03 ±2.95) pg,(211.74 ±75.27)× 109/L,(0.24 ± 0.08)％,t =1,940,2.318,2.079,all P ＜ 0.05];standard difference coefficient of variation of red blood cell distribution width (RDW-CV) was (13.14 ± 1.05)％,lymphocyte number (LYMPH) was (2.01 ± 0.64) × 109/L in the exposed group,it was all lower than those of the control group [(13.38 ±1.54)％,(2.21 ± 1.02) × 109/L,t =-1.989,-1.956,all P ＜ 0.05].The positive rate of glycosuria,uric bravery red,and urine nitrite in routine urine test of exposed group was 17.39％ (32/184),23.36％ (43/184),7.61％ (14/184);it was all higher than those of the control group [(8.25％ (9/109),11.93％ (13/109),0.91％ (1/109),x2 =4.746,5.798,6.309,all P ＜ 0.05].Conclusions Urine chromium accumulation has been found in populations long-term exposed to 2.82-3.22 times excessive Cr6+ through drinking water,which has affected the population's health to some extent.Therefore,it is necessary to speed up the local drinking water improvement project.