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:

Assessment of an automated in vitro basal cytotoxicity test system based on metabolically-competent cells. When in vitro test systems are evaluated for assessment of the toxicity of chemical compounds, particular efforts are made to mimic the in vivo reality as close as possible. Cellular models with appropriate metabolic competence, i.e. with the potency to biotransform chemical compounds, are considered crucial since some metabolites have a different toxicity than their parent compounds. In this study a cell based in vitro test system is proposed to investigate the basal cytotoxicity of several reference chemicals. Both metabolic competent HepaRG cells and cells with no or low hepatic enzyme activity (undifferentiated HepaRG and proliferating HepG2) were used. The classic Neutral Red Uptake (NRU) assay proved to be robust and reliable to be applied as viability assay. The test was performed on a robotic platform, which enabled fully automated and simultaneous screening of the compounds. The outcome of these tests grouped the tested compounds in three categories following their detoxification effect (benzo(a)pyrene, valproic acid), their bio-activation effect (aflatoxin B1) and their specific effect on inhibition of cell proliferation (cycloheximide, sodium lauryl sulphate, atropine sulphate monohydrate, acetylsalicylic acid).
{"Chemical": ["valproic acid", "sodium lauryl sulphate", "aflatoxin B1", "acetylsalicylic acid", "cycloheximide", "benzo(a)pyrene", "atropine sulphate monohydrate", "Neutral Red"]}