Use of wastewater for irrigation of agricultural crops can cause accumulation of pathogens and toxic substances such as heavy metals in food produce and their transmission to the human body when consumed; this has been found to cause many diseases including different kinds of cancer.
Wastewater use can also result in underground aquifer contamination as well.
Irrigation of agricultural fields with contaminated wastewater in the south of Tehran and some other provinces is not a new issue. In recent years it has proved disastrous for consumers’ health and also for vegetable and fruit farmers; the issue compelled authorities to take some measures to fix the problem; but despite preventive laws, some farmers still use contaminated water for irrigation, due to the problems existing in the field of agriculture production, including water scarcity, reports the Iranian Labor News Agency (ILNA).
According to the relevant law passed in 2006, the agriculture ministry is obliged to take necessary measures in cooperation with the energy ministry to solve the problem of farms irrigated with raw sewage.
The preventive measures were supposed to be implemented on priority in the agricultural lands of the following regions: Tehran, Lorestan and Khorasan. One of the measures was planting of non-consumable crops such as cotton. But unfortunately all the directives are forgotten.
Guidelines
Thirty years ago, 3000 samples of soil and water from different agricultural regions were collected to establish guidelines for dealing with the contamination problem. The results indicated that the water and soil of the three above-mentioned regions in particular are contaminated with microbial organisms and heavy metals.
As the pollutants are transmitted through contact of leaves with contaminated water, particularly in leaf vegetables like lettuce, spinach and other vegetables whose leafs are edible, as in the case of ‘Sabzi Khordan’ (Iranian salad greens), some other types of plants including seed plants and cotton, which are not consumables, were recommended as suitable crops.
The main reason for farmers’ willingness to use sewage for crop irrigation is because wastewater is available at lower rates than clean water. Also the fruit and vegetables irrigated with sewage water are bigger in size.
According to farmers, crops irrigated with well waters are three times more expensive than agricultural produce irrigated with sewage water.
At present, Tehran and 11 other provinces are affected by the problem. And according to various reports and studies, the problem has still not been resolved. This has led to a decline in consumption of leafy vegetables, especially in Tehran in recent years.
