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Organic Consumers Association

Research Shows Plants Take Up Drugs, Antibacterials from Biosolids Used as Fertilizers

New research shows that the drugs and contaminants that often contaminant sewage sludge that is used as fertilizer can be taken up by the plants grown in fertilized fields and gardens. Also called 'biosolids' these fertilizers are regularly applied to agricultural fields and are sometimes packaged as organic soil fertilizers sold in home improvement stores. The results raise significant public health concerns about use of biosolids on croplands and in gardens used to grow produce for consumption.

Context

Wastewater treatment plants are important in maintaining a healthy environment. Their primary function is to clean dirty water of pathogens, metals, certain nutrients and some pollutants that exit homes and businesses through showers, toilets, laundry machines, dishwashers and other drains.

During treatment, the sewage is separated into liquids and solids. The extent of treatment can vary, but, generally, bacteria help to break down chemicals present in the dirty water. The water can be aerated and disinfected to kill disease-causing pathogens. The cleaner water - now called effluent - is released into the environment, either directly into rivers, oceans and other natural waterbodies or reused to irrigate crops.

Any solids in the sewage are filtered out. The solid materials - called sewage sludge, or "biosolids" - are dried before disposal. But, getting rid of the solids can be expensive. They can be put in a landfill, incinerated or composted for reuse as fertilizers for crops or home garden/lawn use.

Today, most biosolids are land applied to recover nutrients in the solids. Biosolids are currently regulated by the U.S. Evironmental Protection Agency (EPA) for metals and pathogens, but not for organic contaminants, including pharmaceuticals, cleaning product ingredients and persistent chemicals. The EPA requires testing for only nine pollutants, about 1 percent of the hazardous materials that could be found in sewage.

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