Gross alpha and beta measurements in drinkable water from seven major geographical regions of China and the associated cancer risks.

In this study, human health risk derived from radioactive pollution in drinking water of China was assessed based on gross alpha and beta. Considering the presence of numerous data under the detection limits, the left-censored handling methods were employed to deal with the non-detected values in gross alpha and beta radioactive concentrations. Results show that concentrations of gross alpha and beta range from 4.98 × 10-4 Bq/L to 0.49 Bq/L with a mean value of 0.029 Bq/L and 5.00 × 10-3 Bq/L to 1.26 Bq/L with a mean value of 0.091 Bq/L, respectively. With the average effective dose being 1.41 × 10-2 mSv/y, the annual cancer risk due to radioactive pollution in Chinese drinking water is 7.75 × 10-7 /y. This study aimed to provide an easier method to quantify the radioactive pollution in drinking water and give a scientific basis for making policy decisions on radioactive pollution management.

Co-infection risk assessment of Giardia and Cryptosporidium with HIV considering synergistic effects and age sensitivity using disability-adjusted life years.

Co-infection with multiple pathogens, especially the spread of Giardia and Cryptosporidium in source water among those with immunodeficiency, is common worldwide, which will result in an increase in overall risk. In this study, the quantitative microbial risk assessment model was used to estimate the cumulative risk of co-infection with Giardia and Cryptosporidium promoted by HIV, considering age sensitivity. The sensitivity of population segments with different ages was estimated by the optimization method, based on clinical data of cryptosporidiosis and giardiasis with age structure. The factors of co-infection enhancement were used to quantify HIV synergism with the action of other pathogens. The removal rates of Giardia and Cryptosporidium through water treatment were estimated by a model involving turbidity and particles. The results showed that children (0-4 years) were 17.911-fold more sensitive to infection with Giardia than adults (15-64 years), and that with Cryptosporidium was 10.592-fold. Removal rates of these parasites in water treatment plants in major cities in China were estimated to be 2.03 log10. Considering the HIV-synergistic and age-susceptibility effects, the cumulative risk of exposure to Giardia or Cryptosporidium was about 38.781 × 10-6DALYs (Disability-adjusted life years) per person per year, which was much higher than the reference risk level recommended by the World Health Organization (10-6DALYs). The methodology and results of this study will be useful in better evaluating and reducing the burden due to infection of Giardia and/or Cryptosporidium in China and other countries.

Health risk assessment on N-nitrosodimethylamine in drinking water and food in major cities of China with disability-adjusted life years (DALYs).

In this study, a health risk assessment of N-nitrosodimethylamine (NDMA) in drinking water and food was conducted using disability-adjusted life years (DALYs) in major cities of China. Considering the numerous non-detected values found in drinking water samples, a zero-inflated model was employed to obtain a more precise NDMA concentration distribution function in drinking water. With exogenous chronic daily intake of 1.20 × 10-6 mg/(kg*d), the lifetime cancer risk and disability-adjusted life years of NDMA are 4.01 × 10-5 and 5.52 × 10-6 per person-year (ppy). The disease burden attributable to water sources accounts for nearly 9.94% of total exogenous intake. The contribution rate of vegetables is the largest, followed by cereals, milk products, fish and shrimp, and meat. Taking endogenous sources into consideration, the contribution rates of drinking water and food sources decrease to 0.08% and 0.69%. This study provides a scientific basis for making policy decisions on NDMA pollution management.