Causes of pollution
Ecotoxicology - ecological context

Two main trends are correlated with pollution levels:

• the development of technology, which has led to significant disruption of natural energy flows, and then to disruption of the materials cycle, producing increasing quantities of non-recyclable waste;

• the demographic explosion: it took more than two million years for the human species to reach one billion individuals, a figure it reached in the 19th century (table 1). It took just 120 more years to reach the second billion, thirty more for the third billion, fifteen for the fourth billion and twelve for the fifth. In 1999, humanity reached 6 billion people, six times more than at the beginning of the 19th century, and 6.1 billion by the end of 2000. 7 billion people are expected by 2012.