Among the major technology companies, Apple is the one that has sought to integrate sustainability into its corporate policies most effectively. Among the concrete initiatives undertaken by the Cupertino company are the use of energy from renewable sources and energy-saving programmes. Apple is now working to make its entire supply chain sustainable, starting with its suppliers.

The Supplier Responsibility 2015 Progress Report produced by the company reveals that some suppliers are on "probation" for having violated certain standards, such as the use of child labour, falsified documentation, or having caused significant environmental impacts.

In the case of a first offence, suppliers remain under review until the next audit is completed; if the outcome is negative, or if Apple considers that the supplier is not genuinely committed to change, the working relationship is ended.

The report states that in 2014 audits were carried out at 633 facilities; 85 per cent of them complied with policies against forced labour, 95 per cent did not resort to child labour and 92 per cent observed correct working hours. Overall, 81 per cent of facilities were found to be in compliance with labour policies and human rights.

According to the report, 12 cases of child labour came to light during the investigation; Apple is said to have intervened by requiring the young workers to return to school and by funding their education. 24 facilities were found guilty of discrimination against pregnant women, while 20 facilities carried out medical tests as a pre-condition for employment. The report states that all offenders were ordered to immediately cease discriminatory practices.

Last year's report focused on the use of so-called conflict minerals — that is, minerals sourced from areas marked by severe political and social instability — and Apple had committed to using only certified suppliers in an attempt to eliminate the use of such minerals.