Contamination of drinking water sources by harmful synthetic organic compounds (SOCs), such as pesticides, is a major worldwide problem. Pesticide pollution appears twice in the top ten of The World’s Worst Toxic Pollution Problems Report 2011 by the Blacksmith Institute, and has been indicated in every year’s report since initial publication in 2006. Effective, affordable and scalable green treatment technologies for SOC removal that are accessible to communities in the developing world or in remote areas of developed countries are, however, lacking.
A recent review in Science indicates that the 300 million tons of SOCs produced annually, including five million tons of pesticides, constitute a major impairment to water quality on a global scale. In Thailand, for example, 75 percent of the pesticides used are banned or heavily restricted in the West due to deleterious ecological and human health effects. The Science authors state that “small-scale, household-based removal techniques are often the only possible mitigation strategy due to the lack of a centralized infrastructure,” and call for the development of “reliable, affordable and simple systems that local inhabitants could use with little training.”
Unfortunately, SOCs are not yet ‘on the radar’ of major actors in the water-sanitation-hygiene (WASH) sector of international development.The UN Millennium Development Goals, for example, are only concerned with mitigation of biological agents of waterborne disease. I recently attended a major international conference on global water and health in developing communities. My presentation was the only one that considered SOCs in drinking water and presented a potential treatment technology. Microbial pathogens are often the most immediate threat to human health (e.g. diarrhea) and so focus on these disease agents is warranted. However, we cannot discount the threat of bio-accumulating chemical toxins, such as pesticides. The immediacy and scale of this problem is highlighted by, for example, a survey of Hmong tribe women living in Mae Sa Mai village, Chiang Mai Province, Thailand, that reported detection of DDT in 100 percent of mothers’ milk samples. A number of other biocides were also frequently detected, and infants’ exposure exceeded by up to 20 times the acceptable daily intakes as recommended by UN-FAO and WHO.