This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Dental
[{'content': 'According to OSHA, maximum permissible amount of Ni in dental clinic environment is? \nSelect and explain. \nA. 1 mg, B. 2 mg, C. 3 mg, D. 4 mg', 'role': 'user'}, {'content': 'Answer: A \nExplanation: The former OSHA Permissible Exposure Limit for all forms of inorganic nickel (as Ni) was 1 mg/m3 TWA. Based on the ACGIH recommendation, OSHA proposed revising this limit to 0.1 mg/m3 TWA; this limit is established in the final rule. NIOSH recommends that exposure to any form of inorganic nickel be maintained at or below 0.015 mg/m3.\nRef: https://www.cdc.gov/niosh/pel88/7440-02.html#:~:text=The%20former%20OSHA%20PEL%20for,below%200.015%20mg%2Fm3.', 'role': 'assistant'}]