You will be shown an abstract from a biomedical research paper. Given this abstract, your task is to extract all unique entities of the following types: ["Chemical"].

Please return the output as a JSON object of the format: {"Chemical": ["Arsenic", ...]}. The keys should be entity types and values should be lists of extracted entities belonging to the corresponding type. If you cannot find entities belonging to a specific type, the value should be [].

Only output the JSON object and do not include any additional text.

Abstract:

Dietary exposure to inorganic arsenic of the Hong Kong population: results of the first Hong Kong total diet study. Inorganic arsenic, a human carcinogen, can be found in the environment and food. In the first Hong Kong Total Diet Study, the dietary exposure of the Hong Kong people, including various age-gender subgroups, to inorganic arsenic was estimated for assessing the associated health risk. Food samples, which represented the Hong Kong people's diet, were collected and prepared "as consumed" for analysis. Concentrations of inorganic arsenic, as sum of arsenite (As(III)) and arsenate (As(V)) were determined in 600 composite samples by using inductively coupled plasma mass spectrometry. The dietary exposures were estimated by combining the analytical results with the local food consumption data of the adult population. The mean and 95th percentile of inorganic arsenic exposures of the Hong Kong people were 0.22 and 0.38μg/kg body weight (bw)/day, respectively. Among the 12 age-gender subgroups, the respective exposures ranged from 0.19 to 0.26μg/kg bw/day and from 0.33 to 0.46μg/kg bw/day. The main food category that contributed inorganic arsenic was "cereals and their products" (53.5% of the total exposure), particularly rice. Having considered the carcinogenic risk of inorganic arsenic to humans, it is suggested that efforts should be made to reduce the inorganic arsenic exposure of the Hong Kong population.
{"Chemical": ["As(V)", "arsenic", "arsenite", "arsenate", "As(III)"]}