Devices used to give an indication of whether products have been exposed to inappropriate temperatures that could cause damage during transport, distribution or storage. For example, indicators can be used to show whether frozen foods have been thawed during handling or storage; thaw-ing during distribution can potentially affect quality and safety. Indicator devices often produce a visible, irreversible colour change to show when temperature abuse has occurred. Microbial indicators may also be used to detect exposure to temperature abuse, especially in animal carcasses. For example, poultry products that have been maintained at the correct temperature will have fairly constant counts of coliforms, while those that have been warmed will have higher counts.