The Culinary union will ask Las Vegas casinos and hotels to supply guest room attendants with panic buttons amid national attention to the issue of workplace sexual harassment. The proposal is part of the union’s demands as it readies for talks for 50,000 of its 57,000 employees on a five-year contract with casinos next month, said Bethany Khan, a spokeswoman for Culinary Local 226. Panic buttons would allow guest room attendants to notify security if they are in an uncomfortable or threatening situation. The union will be renegotiating contracts with Caesars, MGM Resorts International and several downtown casinos starting in mid February.