ISLAMABAD: The Asia-Pacific region has failed to control pollution of its rivers,more than 80 per cent of which are considered to be in `poor health`, a new United Nations report reveals.

The report, prepared by the UN Environment Programme (UNEP) for the second forum of ministers and environment authorities of AsiaPacific region opening in Bangkok on Sept 5, says that common pollutants in the region are organics, nutrients, dis-solved salts, heavy metals, pesticides and chemicals from industrial activities.

The sources of the pollution are untreated or partially treated sewage, agricultural runoff, industrial wastewater and landfill leachate, and nutrient and sediments washed from degraded land by heavy rainf all.

Several river basins, including the Indus, have high organic pollution.

This can be further aggravated by other pollution such as increased salinity as seen in the Ganges and Indus river basins.

A major cause of water pollution is poor sanitation, including defecation in the open, leading to contamination of surface and groundwater sources by organics, nutrients and bacterial coliform. In Asia and the Pacific, 1.7 billion people lack access to basic sanitation, and almost 80pc of wastewaterbeing discharged in water bodies with little or no primary treatment.

An estimated 1.8 million deaths occur annually in Asia and the Pacific due to water-related diseases, including diarrhoea and cholera. Salt intrusion and higher turbidity from stronger, frequent storms and erosion from deforestation provide favourable growth conditions in tropical estuaries for bacteria such as Vibrio that causes cholera.

Other diseases related to water, sanitation and hygiene include intestinal nematode infections, protein-energy malnutrition, trachoma, schistosomiasis, lymphatic filariasis, malaria and dengue. Disability-adjusted life years lost due to unsafe water, sanitation and hygiene in the region totals 24.78m per year.

Another factor affecting human health from water pollution is theaccumulation of heavy metal in plants that are then consumed as food. Many studies have looked at accumulations of arsenic, cadmium, copper, lead and mercury in vegetables, rice and other edible plants. The extent of bioaccumulation depends on irrigation methods, much less arsenic accumulation has been observed in rice grown by sprinkler irrigation compared to that grown using continuous flooding irrigation.

The report says that nearly 12pc of the population lives in degraded areas of Asia and the Pacific, and this proportion may increase in years to come with significant social impacts. Direct impacts of large-scale land-use changes include displacement of indigenous people, loss of biodiversity and a reduction in important forest products. Land degradation has had severe impacts on human develop-ment in the region.

The Asia-Pacific region produces more chemicals and waste than any other regions in the world. Over the period of 2012-20, the regional chemical production is expected to grow by 46pc. Major industrial incidents can happen during the processing, storage or transport of potentially hazardous chemicals.

Waste generation in Asia and the Pacific is rising and new and complex waste streams are emerging. Total global waste is around 7 to 10 billion tonnes per year, of which total municipal solid waste is around 2bn tonnes.

With an average generation rate of 1.4kg per person per day, the annual total municipal solid waste for Asia and the Pacific was estimated at around 870m tonnes in 2014, accounting for 43pc of the world`s total.

Alongside the increase in municipalsolid waste generation, Asia and the Pacific is now facing complex waste streams, including e-waste, food waste, construction and demolition waste, disaster waste and marine litter. Open burning is a common treatment of e-waste in many countries, practiced mainly by informal recyclers when they segregate organic and inorganic compounds, with adverse acute and chronic effects on human health and the environment.

Urban areas in the region generate about 1.21m tonnes of municipal solid waste a day. By 2025, this amount will be more than double, to 2.65m tonnes daily. Inadequate treatment of waste can cause pollution and environmental and ecosystem degradation. If not properly collected, waste can decay and cause air pollution, unpleasant odours and degradation of soil, surf ace and groundwater, and eco-systems.