The doses were selected to represent 1, 3 and 9 working days of exposure at the occupational inhalation exposure limit of 3.5 mg/m 3 of CB (as established by the US Occupational Safety and Health Administration (OSHA) and the US National Institute for Occupational Safety and Health (NIOSH))) for a mouse (assuming 1.8 L/h inhalation rate and 33.8% particle deposition in mouse, for an 8 h working day) (Dybing et al., 1997; Jacobsen et al., 2009) .