To analyze the clinical characteristics of drinking-water type endemic arsenism in population lived in the diseased areas before and after water improvement in Inner Mongolia, so as to assess the natural development and the effects of human intervention measures.

Residents of four villages lived in Hangjinhouqi Bayinnaoer city Inner Mongolia were followed-up and their skin lesions were examined in 2004 (before water improvement), 2010 (complete water improvement), 2014 (after water improvement). Meanwhile, blood pressure and heart rate of the subjects were measured. The arsenic poisoning skin damage indexing was in accordance with endemic arsenic poisoning diagnostic criteria (WS/T 211-2001).

Totally, 229, 122, 161 people were investigation in 2004, 2010, 2014, respectively. The clinical grading of arsenic exposed population were mainly normal and suspicious cases in 2004, accounting for 61.6% (141/229) and 22.7% (52/229), respectively. The clinical grading of normal, suspicious, mild and severe cases were 20.5% (25/122), 31.1% (38/122) and 48.4% (59/122), respectively, in 2010, which were significantly different compared with those of 2004 (χ² = 68.53, P < 0.01). The clinical grading percentages of normal and suspicious of the subjects in 2014 were 46.6% (75/161) and 39.8%(64/161), respectively, which were significantly different compared with those of 2010 (χ² = 45.22, P < 0.01). Meanwhile, 91 subjects examined in 2004 were re-examined in 2010 and 47 subjects examined in 2010 were re-examined in 2014. Totally, 12 cases were migitation, accounting for 13.2% (12/91), 52 cases were aggravation, accounting for 57.1% (52/91) in 2010, and 25 cases were migitation, accounting for 53.2% (25/47), 9 cases were aggravation, accounting for 19.1% (9/47) in 2014. The differences of skin lesion transition between these two periods were significant (χ² = 28.66, P < 0.05). In addition, the systolic pressures and diastolic pressure of the subjects were (132.19 ± 21.21), (126.99 ± 18.32), (147.69 ± 22.65); (84.88 ± 14.13), (76.52 ± 10.08), (84.39 ± 13.89)mmHg in 2004, 2010 and 2014, respectively, which declined in 2010 compared with them of 2004 (all P < 0.05) and raised in 2014 compared with them of 2010 (all P < 0.01). The heart rate of the subjects were (76.05 ± 12.56), (78.86 ± 11.69), (82.05 ± 11.26)times/min. The heart rate of the subjects raised in 2010 and 2014 compared with that of 2004 (all P < 0.05).

The skin lesions induced by arsenism could be effectively alleviated through water improvement, but the late stage changes such as the cardiovascular system injury are still worthy of attention.

Arsenism; Drinking; Outcome assessment