From the BA website;
The content of the spray used by British Airways is designated by the World Health Organisation (WHO) and is based on the insecticide d-phenothrin. Spray cans contain 2.9% d-phenothrin by weight, 57.1% isoparaffinic solvent and 40% HFC R 134a propellant. A WHO expert committee on the safe use of pesticides has agreed there is no evidence to suggest these insecticides present any toxic hazard to the passengers or crew - provided the correct procedures are followed.