In 2001, certain countries were moving to enforce the 'Essential Requirements' as a part of the [European Directive on Packaging and Packaging Waste]. The 'Essential Requirements' require manufacturers to look at each package and its components intended for sale in Europe. They must assess if the item is recoverable (recyclable, compostable, combustible with a positive BTU value), reusable, source reduced and compliant with applicable heavy metal limits and other noxious substances. For example, an aluminium container with a steel top may not pass the essential requirements. Moreover, companies are supposed to test their packaging for the presence of heavy metals, with additional tests if they claim it is compostable.