(NaturalNews) Could poo irrigation techniques be causing heavy metals to build up in produce? New research indicates that irrigating agricultural land with wastewater leads to an accumulation of heavy metals in the soil, which in turn leads to heavy metals in the food supply.

Recently published by a group of researchers from India, the study found that vegetables grown in soil that was in the vicinity of wastewater drainage areas were not fit for consumption. The researchers found that tuberous and leafy vegetables posed the greatest risk and had the highest hazard quotients across the board, regardless of irrigation techniques. The researchers also stated: "Spinach was the most hazardous among all as the hazard quotient with respect to cobalt and copper was highest in spinach."

One of the key issues is that while the wastewater itself may not seem alarmingly high in heavy metals, these levels become concentrated after reaching the soil. The buildup is essentially continuous; every time the soil is watered with wastewater, more heavy metals are added. As industrialization continues to spread and populations continue to skyrocket, many countries have turned to recycling wastewater as a means of conserving resources. Unfortunately, while this is effective, the lack of proper filtration has also led to an increase in human consumption of heavy metals worldwide. The researchers write: "Long term use of wastewater for irrigation can cause accumulation of these metals in soil which can be further translocated to food crops and thus enter food chain."

The researchers state in their conclusion that while several servings of vegetables should be included as part of a healthy diet, "injudicious agricultural practices" make this seemingly healthy choice a serious threat to human health. The study authors suggest that consumption of tuberous and leafy vegetables from wastewater sites, or sites within wastewater drainage vicinity, should be avoided. The researchers also note: "[T]hese sites should be used for cultivation of non-food crops."

This is not exactly a new finding. The problems associated with wastewater contamination of soil have been an ongoing issue. A 2013 report from the European Commission notes that many countries use wastewater to irrigate farmland under the guise of environmental benefits. They say that in addition to economically solving the issue of what to do with wastewater, it also helps to "enrich" the soil. Unfortunately, they are "enriching" the soil with toxins, heavy metals and who knows what else.