Yet another important reason for consumers in the United States and throughout the world to use natural products whenever possible, to meet their daily needs.
Whether it’s chemical disinfectants, pharmaceutical drugs or hormone-disrupting phthalates added to plastics to make them less brittle, traces of these toxic chemicals are turning up with more frequency in American farm soil, where treated sludge is applied to the ground as fertilizer.
Sludge, which is the name for biological and organic waste solids that are separated from sewer water at treatment plants, makes a great, natural fertilizer, as it’s rich in nutrients that help plants grow and improve soil quality. Fertilizing crops with sludge is also a good idea from an environmental standpoint, as it greatly reduces the amount of “biosolids” that have to be stored in landfills.
Close to half of treated sludge and sewer sludge from American sewage treatment plants — about seven dry tons a year — is applied to farmland, according to an article that appeared earlier this year in Scientific American.
Researchers from the U.S. Geological Survey took soil samples from a wheat field in eastern Colorado and looked for the presence of 57 “emerging” toxic chemicals that are increasingly being found in the environment.
Some of the pollutants in the soil were chemicals used in antibacterial soaps, cleaners, cosmetics, fragrances, and prescription pharmaceuticals, including Warfarin, hormone birth control pills, and antidepressants like Prozac.
The researchers were alarmed because they discovered that there was a tendency for these chemicals to migrate downward into the soil, raising the danger that groundwater — extracted from below the surface for drinking and to irrigate crops — could get sufficiently contaminated to become toxic. If these chemicals are migrating into underground aquifers, they could also contaminate private water wells used by many rural residents for drinking water.
Of the 57 chemicals that were examined, 10 were found at land depths of between 7 and 50 inches — 18 months after the sludge had been applied to the soil. These compounds had not been in the soil before the treated sludge was applied.
The commonly used antibacterial, antiviral and antifungal chemical triclosan was found at the highest concentration (156 parts per billion) in deep soil, at 7 to 14 inches from the surface. Triclosan is often added to consumer products, including hand soaps, shampoos, deodorants, toothpastes, toys, bedding, trash bags and others. It is also used in hospital settings in surgical scrubs, hand washes and in a solution for certain patients with antibiotic-resistant skin infections. (Source: Wikipedia.)
Scientists at the U.S. Food and Drug Administration are concerned that the use of triclosan and other antibacterial compounds could be contributing to antibiotic resistance in the population. In addition, previous studies have shown that triclosan is linked to disruption of different hormones in animals. The safety of triclosan is currently under review by the FDA and Health Canada.
Treatment of sewage waste is mandatory in the United States; the process reduces the number of potential disease-causing microorganisms, but it does not remove most chemicals. While crops examined in the study demonstrated little uptake of the chemicals, rain and snow are able to push the compounds into the soil. Because eastern Colorado is a semi-arid region, the findings show that these toxic chemicals can penetrate soil even in drier regions, according to the researchers.
By Jamell Andrews
Perhaps biosolids are a bit like the canary in the mine. If there is evidence of toxicity to the environment from components of our personal care products and medicines, it may show up first in the effects on land where biosolids have been recycled. So far, good news is that no adverse effects on soil micro or macro flora/fauna have been observed. That doesn’t mean that we don’t owe it to ourselves to keep studying pathways of potential exposure. As it happens in science, some other scientists are not convinced that the study you have cited will be replicated in whole, because the conjectured pathways seem implausible. We will learn in time. Further good news, some of those compounds in that study most resistant to breakdown in soil, such as triclosan, rightfully have attracted their own opponents, and those of us in the wastewater industry welcome their future disappearance in time from our everyday flushes made to public sewers. But, stepping back a moment, in a world where 7.3 billion people live, if we can’t figure out how to reuse/recover/repurpose our own excreta, how is there any hope of ever doing so with solid wastes which are 10X more massive, intractable, and potentially toxic? (BTW, what is that photograph? certainly not recognizable as anything dealing with biosolids)