Most plastics do not biodegrade readily, however, they do still degrade in the environment because of the effects of UV-light, oxygen, water and pollutants. This combination is often generalised as polymer weathering. Chain breaking by weathering causes increasing embrittlement of plastic items, which eventually causes them to break apart. Fragmentation then continues until eventually microplastics are formed. As the particle sizes get smaller, so their combined surface area increases. This facilitates the leaching of additives out of plastic and into the environment. Many controversies associated with plastics actually relate to these additives.