Background The
safety of
drinking water is closely related to people's
health. In recent years, relevant studies have identified some
health related problems with
drinking water in
Inner Mongolia Autonomous Region. The complex and diverse natural
environment embraced by the vast jurisdiction of the region may
lead to uneven
drinking water quality across the region. Objective To evaluate eight
chemicals including
arsenic,
cadmium,
chromium (hexavalent),
lead,
mercury,
fluoride,
trichloromethane, and
carbon tetrachloride in urban
drinking water in
Inner Mongolia Autonomous Region in 2021, and to provide reference for optimizing urban
water supply system and ideas for further developing
strategies to promote
population health.
Methods A total of 1228
monitoring sites were set up in
urban areas of
Inner Mongolia, and
water samples were collected once in
dry season (May) and once in
wet season (August−September). Eight
chemicals of interest in
drinking water were detected according to the Standard examination
methods for
drinking water, and assessed for
health risks using the
health risk assessment model recommended by the
United States Environmental Protection Agency (
USEPA) and following the Technical guide for
environmental health risk assessment of chemical exposure.
Mann-Whitney U test was used to compare the concentrations of eight
chemicals in urban
drinking water by
water seasons and
water sample types. Results In 2021, a total of 2381 samples of urban
drinking water were tested in the
Inner Mongolia Autonomous Region, including 1195 samples in
wet season and 1186 samples in
dry season; 389 samples of finished
water and 1992 samples of tap
water. The positive rates of
arsenic and
fluoride were 26.25% and 96.77%, respectively. The positive rates of
cadmium,
chromium (hexavalent),
lead,
mercury,
trichloromethane, and
carbon tetrachloride were 6.22%, 16.63%, 6.09%, 16.67%, 18.98%, and 8.36%, respectively. The exceeding standard rate of
fluoride was 4.87%.
Trichloromethane and
carbon tetrachloride were qualified in all samples. There were statistical differences in the concentrations of
arsenic,
cadmium,
chromium (hexavalent),
lead, and
carbon tetrachloride in urban
drinking water between
water seasons (Z=−3.847, P<0.05; Z=2.464, P=0.014; Z=−3.129, P=0.002; Z=4.341, P<0.05; Z=4.342, P<0.05). Only
fluoride concentration was found statistically different among different
water sample types (Z=−2.287, P=0.022). The non-carcinogenic
risks of
ingestion and dermal exposure to each chemical in
drinking water by
water seasons and
water sample types were all less than 1, but the P95 total non-carcinogenic
risks of oral exposure were greater than 1. The P95 carcinogenic
risks of oral exposure to some
chemicals in
drinking water by
water seasons and
water sample types were>10−4, which suggested carcinogenic
risks, while the carcinogenic
risks of dermal explore to
chemicals were all less than 10−6. Conclusion In 2021, urban
drinking water in
Inner Mongolia Autonomous Region is generally safe, but
arsenic,
cadmium,
chromium (hexavalent),
lead,
mercury, and
fluoride still exceed the national limits, posing certain
health risks.