Pollutants Can Lurk and Hide
The health implications of polluting the environment weigh increasingly on our public consciousness, and pharmaceutical wastes continue to be a main culprit. Now a Tel Aviv University researcher says that current testing for these dangerous contaminants isn't going far enough. Dr. Dror Avisar, head of the Hydro-Chemistry Laboratory at TAU's Department of Geography and the Human Environment, says that, when our environment doesn't test positive for the presence of a specific drug, we assume it's not there. But through biological or chemical processes such as sun exposure or oxidization, drugs break down, or degrade, into different forms — and could still be lurking in our water or soil in different forms.
In his lab, Dr. Avisar is doing extensive testing to determine how drugs degrade and identify the many forms they take in the environment. He has published his findings in Environmental Chemistry and the Journal of Environmental Science and Health.
The use of pharmaceuticals and personal care products (PPCPs) is on the rise with an estimated increase from 2 billion to 3.9 billion annual prescriptions between 1999 and 2009 in the United States alone. PPCPs enter into the environment through individual human activity and as residues from manufacturing, agribusiness, veterinary use, and hospital and community use. Individuals may add PPCPs to the environment through waste excretion and bathing as well as by directly disposing of unused medications to septic tanks, sewers, or trash. Because PPCPs tend to dissolve relatively easily and do not evaporate at normal temperatures, they often end up in soil and water bodies.
Some PPCPs are broken down or processed easily by a human or animal body and/or degrade quickly in the environment . However, others do not break down or degrade easily. The likelihood or ease with which an individual substance will break down depends on its chemical makeup and the metabolic pathway of the compound.
A study by the U.S. Geological Survey report published in 2002 found detectable quantities of PPCPs in 80 percent of a sampling of 139 susceptible streams in 30 states. The most common pharmaceuticals detected were steroids and nonprescription drugs as well as detergents, fire retardants, pesticides, natural and synthetic hormones, and an assortment of antibiotics and prescription medications.
Drug products have been in our environment for years, whether they derive from domestic (residential)waste water, hospitals, industry or agriculture. But those who are searching for these drugs in the environment are typically looking for known compounds — parent drugs — such as antibiotics, pain killers, lipid controllers, anti-psychotic medications and many more.
Dr. Avisar explains. "We may have several degradation products with even higher levels of bioactivity." Not only do environmental scientists need to identify the degraded products, but they must also understand the biological-chemical processes that produce them in natural environments. When they degrade, compounds form new chemicals entirely, he cautions.
Dr. Avisar and his research group have been working to simulate environmental conditions identical to our natural environment, down to the last molecule, in order to identify the conditions under which compounds degrade, how they degrade, and the resulting chemical products. Among the factors they consider are sun exposure, water composition, temperatures, pH levels and organic content.
Currently using amoxicillin, a common antibiotic prescribed for bacterial infections such as strep throat, as a test case, Dr. Avisar has successfully identified nine degradation products with different levels of stability. Two may even be toxic, he notes.
According to Dr. Avisar, who will soon expand his research to include the degraded products of chemotherapy drugs, his research is breaking new ground, extending past research.
For further information: http://www.impactlab.net/wp-content/uploads/2009/01/water-pollution.jpg