The design objectives behind the bin were efficient use of space and safety: to provide at least as much space as the older round bins, whilst reducing the risk of injury caused by moving it. This is important for both the householder and the waste collector, who risked injury through lifting the traditional bin or from sharp, or possibly contaminated objects in garbage bags. Standardisation of dimensions is important because the bins must be lifted by a standard sized hoist on the dustcart. The bins are lifted by the lip at the front which must be designed for maximum stiffness and mechanical strength. The underside of the lip is therefore reinforced by numerous ribs in the case of the thermoplastic bins. Steel bins have a much simpler lip owing to the properties of steel.
For a recycling program to work, having a large, stable supply of recyclable material is crucial. Three legislative options have been used to create such a supply: mandatory recycling collection, container deposit legislation, and refuse bans. Mandatory collection laws set recycling targets for cities to aim for, usually in the form that a certain percentage of a material must be diverted from the city's waste stream by a target date. The city is then responsible for working to meet this target.
Levels of metals recycling are generally low. In 2010, the International Resource Panel, hosted by the United Nations Environment Programme (UNEP) published reports on metal stocks that exist within society and their recycling rates. The Panel reported that the increase in the use of metals during the 20th and into the 21st century has led to a substantial shift in metal stocks from below ground to use in applications within society above ground. For example, the in-use stock of copper in the USA grew from 73 to 238 kg per capita between 1932 and 1999.
Tierney also points out that "the prices paid for scrap materials are a measure of their environmental value as recyclables. Scrap aluminum fetches a high price because recycling it consumes so much less energy than manufacturing new aluminum."