Only 20% of Tehran's sewage is properly treated and the rest is contaminating underground water reservoirs and agricultural lands, a member of the Iranian parliament has warned.

Based on tests carried out at vegetable and fruit markets, traces of heavy and illegal toxic metals in root vegetables, including carrots, potatoes and onions are much more than admissible levels, said the spokesman of parliament's Agriculture Commission, Ali-Mohammad Shaeri.

Lambasting the Department of Environment (DoE) for negligence in supervising Tehran's sewage system, Shaeri noted, "While the whole world is moving toward organic agriculture, the Ministry of Agriculture Jihad should not allow farmers to irrigate their lands with sewage water."

He also maintained, "DoE needs more supervision on agricultural lands in southern parts of Tehran" and called on Tehran's prosecutor general to step in.

Tehran with an estimated 8,700,000 population, is one of the largest cities in the world without a modern sewage system.

Expansion of the wastewater network development project is one of the most important urban projects underway in Tehran since four decades, but the lack of funding for the major undertaking plus the fast development of urban areas have impeded completion, reported Iran Financial Tribune.

“Nearly 10,000 km of underground pipes should be installed to cover the city’s entire wastewater system. So far 6,000 km of pipelines have been laid,” says Mohammad Salari, head of the Urban Planning and Architecture Commission of the Tehran City Council (TCC).

“Constraints in funding, rapid growth of urban areas and narrow alleys in the older districts are among the main reasons that work has been delayed,” pro-reform daily, Sharq, has quoted him as saying.