Hand washing. Hand washing, also spelled handwashing and known as hand hygiene, is the act of cleaning one's hands for the purpose of removing soil, dirt, and microorganisms. This may be done with or without the use of water, other liquids, or soap.
Sunscreen does expire. The molecules in suntan lotion (such as homosalate and octyl salicylate) block the penetration of UV radiation by acting as filters and absorbing and reflecting high energy UV. Over time these molecules break down and lose effectiveness, kind of like expired cold medicine or vitamins.
04-04-2011, 10:44 AM. Teeth whitening gels do have an expiry date and usually expire in around 1 year. Your particular whitening gel may have been originally supplied in a bulk bag or box and the expiry maybe written on the bag or the box. You should call the dental clinic that provided the gel and find out when that gel expires.