Chemicals are added to plastics for a variety of reasons. For example, plasticisers such as phthalates are used to make products flexible. Flame retardants are added to furniture and electronics to make them more heat resistant. While these are just two examples, many more substances are used to improve the durability of products, to create water resistance or to add specific colours, for example. In plastic packaging alone, over 4,000 chemicals may or may not be used.