The Federal Government and the government of any State or political subdivision of a State may establish and continue in effect, with respect to a household substance for its own use, a standard for special packaging or related requirement which is designed to protect against a risk of illness or injury with respect to which a standard for special packaging or related requirement is in effect under this Act and which is not identical to such standard or requirement if the Federal, State, or political subdivision standard or requirement provides a higher degree of protection from such risk of illness or injury than the standard or requirement in effect under this Act.