The World Health Organization says the decline of the global ecosystem poses a serious threat to human health.
In a WHO report published Friday scientists warn that pressures on the environment could have unpredictable and potentially severe impacts on health.
It says more than one billion people lack access to safe water supplies, while more than two billion lack adequate sanitation, due in part to ecosystem depletion and contamination.
The report says consequences to human health from environmental degradation will grow significantly worse in the next 50 years.
The report says poor populations dependent on natural ecosystems for basic needs face the greatest risk of health problems. Regions of concern include sub-Saharan Africa, Central Asia, parts of Latin America, and areas in South and Southeast Asia.
Some information for this report provided by AP and Reuters.