[Estimation of Health Risk and Enaction of Safety Standards of N-nitrosodimethylamine(NDMA) in Drinking Waters in China].

Nitrosamines such as nitrosodimethylamine(NDMA) in drinking water have recently attracted great attention because of their high carcinogenicity and high detection rate. Nitrosamines have also been repeatedly detected in drinking water in our country, leading to a lot of concerns about our drinking water safety. However, China has not yet formulated the relevant drinking water safety standards. In order to evaluate the health risks caused by NDMA in drinking water and to provide recommendations for the development of drinking water safety standards, the method of disability-adjusted life years(DALYs) and the two-stage disease model were used to estimate the health risk of liver cancer caused by intake of NDMA in drinking water. The data of this study were collected from two large-scale water quality surveys conducted in 35 cities in China from November 2009 to May 2012, and the detection conducted by Chen Chao et al. in 23 cities in China from 2012 to 2014, with a total of 146 water plants data. The results showed that mean(8.97 ng·L-1) and median(2.90 ng·L-1) NDMA concentrations were both not very high except in some special areas. The incidence of life-long cancer was 5.69×10-6 and 5.69 times as high as the negligible risk value(1×10-6) specified by the US EPA. The total disease burden of NDMA was 844.15 person-years, of which the death loss was 818.31 person-years, accounting for 96.9%. The incapacity loss was 25.84 person-years, accounting for 3.1% in comparison. Death loss was greater than the loss of incapacity. The disease burden was highest in the age group of 55-60 years(129.40 person-years), followed by 45-50 years(120.44 person-years). The burden of disease was higher in middle-aged and elderly people. The averaged loss was 6.27×10-7 DALYs per person per year in our country. Only considering the health risk factors, NDMA concentration safety standards should be 6.12 ng·L-1. According to the specific national conditions, the NDMA safety standard in the range of 6-40 ng·L-1 was recommended. On one hand, we can control the concentration of NDMA in drinking water, to reduce health risks as far as possible, and on the other hand, we can also ensure the effectiveness of disinfection of drinking water treatments. China's economic and water treatment technological level and other factors should also be taken into consideration in the near future. In view of potential health risks of NDMA, it's necessary to adopt more effective, economical and also environmental water treatment techniques and develop reasonable safety standards to ensure the quality of drinking water and people's health.

[Accumulated Health Risk Assessment of Arsenic in Drinking Water of Major Cities of China].

Based on the drinking water quality survey data of China's major cities, the existing disease burden calculation method was improved and disability-adjusted life years (DALYs) was taken as the end of evaluation to assess the health risk of arsenic contamination level. The results showed that the concentration of arsenic in drinking water of major cities in China was very low (0.53 µg·L-1), far below the national limit (10 µg·L-1) and the total lifetime cancer incidence was 1.76×10-5. The order of risks of different kinds of cancers was:skin cancer (1.53×10-5) > lung cancer (2.25×10-6) > liver cancer (2.30×10-8) > bladder cancer (1.34×10-10) and the average disease burden was 1.91×10-6 per person-year. Among them, skin cancer and lung cancer accounted for 70.2% and 29.0% respectively, and the disease burdens of bladder cancer and liver cancer were negligible, but the overall cancer risk was still higher than the recommended level of 10-6 per person-year by WHO. Although the arsenic level of drinking water in China was not high, the risk of cancer could not be ignored. Thus more effective and feasible measures should be taken to reduce arsenic concentration to protect people's drinking water safety in the future.

Effect of corneal graft diameter on therapeutic penetrating keratoplasty for fungal keratitis.

AIM: To evaluate the effect of corneal graft diameter on therapeutic penetrating keratoplasty (PKP) for fungal keratitis. METHODS: A total of 116 patients (116 eyes) suffered from fungal keratitis underwent PKP at the Affiliated Hospital of Medical College Qingdao University from May 2006 to May 2010. They were divided into two groups according to the corneal graft diameter. 64 eyes' corneal graft diameter was 8.00mm or larger and 52 eyes' graft diameter was smaller than 8.00mm. The follow-up time was 2 years. The postoperative visual acuity and complications were documented and compared. RESULTS: Sixty-two (96.88%) eyes and fifty (96.15%) eyes preserved eyeballs respectively in two groups. There was no statistical difference in postoperative visual acuity (P=0.961), corneal graft clear rate (P=0.132) or the incidence of recurred fungal infection (P=0.770) between two groups. But there was a higher incidence of graft rejection (P=0.020) and secondary glaucoma (P=0.039) in group with corneal graft diameter 8.00mm or larger. CONCLUSION: PKP is an effective treatment approach for fungal keratitis. There is a higher incidence of complications in large-diameter PKP for fungal keratitis. Effective, preventive and therapeutic measures can improve the prognosis.