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Our Crops Are on Drugs


Are their cumulative effects of food irrigated with wastewater?


Are Your Vegetables on Drugs?

A new study conducted on zucchini plants suggests that pharmaceuticals in biosolid fertilizers could be harming your veggies.

Fertilizing crops with biosolids—a combination of human, commercial, and industrial wastes otherwise known by critics as “sewage sludge”—is a common but controversialpractice.

On the one hand, municipalities argue, it is much more environmentally sound to recycle nutrients that would otherwise be sent to landfills. The use of these fertilizers also cuts down on the amount of man-made fertilizers needed to boost crops and keep soils healthy.

On the other hand, biosolids have often raised safety concerns, and the quality and safety can vary depending how they’ve been treated. The U.S. Department of Agriculture’s (USDA) National Organic Standards prohibit their use in organic agriculture because of concerns over contamination from hormones, steroids, and pathogens. And there has been a passionate debate over whether biosolids are safe to use because of the risk of contamination.

Despite the fact that there are many substances found in biosolids, the U.S. Environmental Protection Agency (EPA) only regulates a few including pathogens and heavy metals. And the agency has no control over the level of pharmaceuticals in biosolids or in wastewater.Farmers and gardeners use biosolids to fertilize their land and maintain lawns in all 50 U.S. states and in many other countries around the world. Although, according to EPA, biosolids are used on just 1 percent of U.S. farmland.Now a new study suggests that the pharmaceuticals in these biosolid fertilizers may have a detrimental effect on crops.

Pharma on the Farm

The study, out this week from the journal Environmental Science and Technology, found that zucchini plants were damaged by two common pharmaceuticals: carbamazepine, which is used to treat epileptic seizures, and verapamil which controls high blood pressure.The researchers chose to study zucchinis because the plants produce a large fruit, which is easy to measure. But the study’s results could apply to a variety or crops and vegetables, says Laura Carter, a PhD student at the University of York in the United Kingdom, and one of the study’s authors.

“Drugs have been detected in biosolids destined for land application and in reclaimed wastewater applied to land,” says Carter. “If you link this back to studies such as ours, which show they are taken up by plants, there is a widespread impact that may occur.”

Biosolid fertilizers can contain concentrated cocktails of pharmaceutical drugs. The medicines find their way into the fertilizers when wastewater treatment plants don’t adequately remove the drugs after people ingest and excrete them. These pharmaceuticals can also contaminate reclaimed water used for agricultural irrigation and leak into the environment polluting rivers, often causing male fish to develop female anatomy.

When scientists first started to find pharmaceuticals in biosolids they were worried that edible plants could absorb the drugs from the soil and potentially harm people who ate them. But most studies to date have found little risk to people. The plants, however, have not fared so well.

Carter and her colleagues at the Australia’s Commonwealth Scientific and Industrial Research Organization (where she was located before moving to York), watched what happened to the zucchini plants when they were exposed to drugs at the low concentrations that they might find in the environment (0.005mg/kg). They also studied the effects at a range of higher concentrations up to 10mg/kg.

The research team discovered that, even at low levels, the drugs interfered with important plant hormones that support the zucchini’s defenses against predator attacks and diseases. Gardeners and farmers using contaminated biosolids might not see any visible impact on their crops and vegetables, but “something might be going on in the plant’s hormonal system,” says Carter. Additional studies are needed to confirm that the altered hormones undermine the plant’s defenses, she says.

“This study shows there is an effect at the low concentrations seen in the environment. Other studies have only looked at very high drug concentration that are unrealistic,” says Tomer Malchi, an environmental chemist at the Hebrew University of Jerusalem in Israel who specializes in pharmaceuticals in soil and water.

This is Your Zucchini on Drugs?

At some higher concentrations, the drugged-up zucchinis’ roots were stunted and their leaves developed burnt edges and white spots. “We thought the discoloration meant that the plants were suffering from a nutrient deficiency,” says Carter. But instead they found that the damaged plants had higher levels of some essential nutrients such as potassium, compared to control plants that were not exposed to any drugs. More essential nutrients can be good thing, but if the levels become too high they poison the plant, says Carter.

The drugs also damaged the zucchini’s alchemic ability to make its own energy from sunlight, the process known as photosynthesis. At the higher drug concentrations, the research team saw drops in the leaves’ levels of chlorophyll a, the substance that makes plant leaves green. “This suggests a reduction in the photosynthetic ability of the plant,” says Carter. Less photosynthesis means less energy for the plant to grow an edible zucchini.

The results don’t sound the death knell for biosolids just yet, says Dr. Christopher Higgins, an environmental scientist at the Colorado School of Mines. But he cautions against civil engineering projects that produce large amounts of biosolids to reclaim land, such as the Loop project in Seattle, Washington, which recycles wastewater in Kings County to produce a biosolid fertilizer that is used in forestry projects and on local farms. (The makers of Loop contend that it is safe, however).

“There are some risks, such as the effect of pharmaceuticals, that need to be captured before we go off and do something like that,” he says.

“There are no controls at most wastewater treatment plants to ensure you have low concentrations of pharmaceuticals in biosolids. There is no telling what you might have at high concentrations,” says Higgins.

What Can Be Done

Higgins urges industry and regulators to pay more attention to what substances are discharged into wastewater treatment plants. “It’s not just the impacts on biosolids that can be problematic. Drug manufacturing facilities, for example, can release very high concentrations of drugs into wastewater,” he says.

For gardeners, identifying fertilizer made with biosolids can be tricky, as companies are not required to tell consumers when they’re being used. And while applying small quantities in your backyard might not be cause for concern, Malchi says a close eye should be kept on the impacts of large-scale commercial use.

“No one really knows how much of these compounds are being introduced into the environment,” he adds.


Approximately 40% of the world’s food is cultivated in irrigated areas and  10% of the world’s population consumes food irrigated with wastewater.

How safe is it to irrigate crops with wastewater?  After treatment, wastewater still contains an array of Pharmaceuticals-OTC Medications-Vitamins.“These substances do not tend to accumulate in vegetables, including tomatoes and lettuce that people often eat raw,” claims a 2016 study.Alison Franklin and a team of researchers at the Pennsylvania State University recently published a 2016 study in which they evaluated compound trails from effluent to wheat plants irrigated by treated wastewater. The study once again revealed that the compounds were absorbed by plants, though none in toxic levels. The team’s research found that plants’ outer surfaces stored the majority of the compounds. Insignificant amounts were found in the edible portion, i.e., grain.As reassuring as this may be, it makes one wonder about the cumulative effect it could have on livestock that consume large amounts of these wastewater-borne contaminants in their feed. Could it put our food supply at risk or accelerate the development of antibiotic-resistant bacteria?

With increasing water scarcity worldwide, it seems that this issue deserves further research and discussion. As consumers, policy makers, and citizens of the world, it’s imperative that we understand the cumulative effects of irrigating with wastewater and carefully manage the risks prior to adopting the practice for agricultural purposes.

Water flushed down toilets or drained in sinks enters sewage treatment plants and is processed to remove contaminants and disease-causing microbes. Although this treated water is considered safe enough to drink, it’s typically released into rivers and streams as it  still contains traces of Pharmaceuticals-OTC Medications-Vitamins.

Research has found 20 different pharmaceuticals and personal care products under realistic field conditions.   They could accumulate to potentially dangerous levels in a number of foods, including carrots, bell peppers, tomatoes, cucumbers, lettuce, spinach, celery and cabbage. The researchers specifically chose foods that are often eaten raw, because cooking can destroy certain contaminants.

All the crops absorbed the ingredients from Pharmaceuticals-OTC Medications-Vitamins,  such as an epilepsy medication, the antibacterial agent triclosan, a tranquilizer and numerous other medications — the levels of these contaminants were low the investigators found.

The study revealed, however, that leafy vegetables absorbed the highest levels of contaminants. The researchers also noted that young children, older people and those with chronic diseases may be more susceptible to even low levels of these trace ingredients from Pharmaceuticals-OTC Medications-Vitamins.

Although the United States only recycles about 2 percent to 3 percent of its wastewater, predicted water shortages could substantially increase the use of recycled sewage water around the world, the researchers say.

However, you need to know that as we keep flushing down the toilet or sink our Pharmaceuticals-OTC Medications-Vitamins we are continually raising the levels in our drinking water.  ONCE THERE IT CANNOT BE REMOVED.

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