Screening of high-arsenic water resources in Dali Prefecture, Yunnan / 中国地方病学杂志

ABSTRACT

Objective To find out the distribution characteristics of drinking water with high arsenic in Dali Prefecture, Yunnan. Methods General investigation plus sampling survey was adopted in the city of Dali and 11 counties. The arsenic content in water was tested by half-quantitative fast reagent-box method. The water samples exceeding the standard(≥0.03 mg/L) were re-tested by silver diethyldithiocarbamate eolorimetric method or mercury-atomic fluorescence spectrometric method. Population and children exposed by high-arsenic were statistically analyzed. Results Arsenic content in 15 180 samples from 2639 villages are screened, of which 14 976 samples were less than 0.01 mg/L, reaching 98.66% (14 976/15 180); 110 samples was no less than 0.05 mg/L, only accounting for 0.72%(110/15 180). Water sources with excessive arsenic was found in 29 villages, in a percentage of 1.1% of all covered villages(29/2639). The samples were constituted of 10 399 portions of well water(well was less than 10 m deep), 3903 from spring, 93 from river water, 69 from hot spring water, 26 from reservoir water and 690 from surface water. And for the samples which arsenic content were ≥0.05 mg/L, 89 samples(0.86%, 89/10 399) were from well water, 15 from spring water(0.38%, 15/3903) and 6 from spring water(8.70%, 6/69). A total of 1 561 553 individuals were investigated, in a percentage of 67.83%(1 561 553/2 302 156) of the whole population, among those 420 513 were children, rating 26.93% of the investigated population(420 513/1 561 553); 27 865 were exposed to arsenic, accounting for 1.78% of the investigated population 27 865/1 561 553; 8993 children were exposed, rating 2.14% of the investigated population(8993/420 513). Conclusions There exists high-arsenic water resources in Dali Prefecture, Yunan, so the local inhabitants are in the danger of high-arsenic exposure. Urgent attention shall be paid for the endemic arsenic including investigation, prevention and control.