November 14, 2000
You might not have a prescription for Prozac, but does that mean you're not ingesting the drug? A Tulane team of researchers is investigating levels of pharmaceutical contamination in the Mississippi River in an effort to find out how much of the active ingredients in common drugs find their way into our surface and drinking water resources.
"We consume pharmaceuticals, and often there's a residual amount or a metabolized form of those drugs that work their way through our bodies and get into the sewer system," explained Glen Boyd, assistant professor with the Department of Civil and Environmental Engineering.
The pharmaceuticals may remain as low-level concentrations of residual contaminants through the wastewater treatment process and may be discharged with the effluents from the treatment plants. "There are a lot of wastewater treatment plants that discharge into the Mississippi River," Boyd said. "And we use the Mississippi River as our drinking water source."
Other sources for contamination by pharmaceuticals and personal care products (PPCPs) include animal, household and industrial wastes. Whether or not these contaminants pose a risk to human health or the environment is still an open question. Boyd noted that the concentrations identified so far are rather low--close to analytical detection limits--in the range of 10 nanograms per liter.
"That's a hundred times lower than many of our currently regulated compounds," Boyd said. Even so, it can't be assumed that the contaminants, which are constantly being introduced into the water cycle at low levels, are harmless. There needs to be a lot of environmental studies and health studies to see what the long-term impacts are, Boyd said.
"We need to understand the cumulative effects of being exposed to many different drugs at very low levels." But the research is only just beginning. Boyd has long worked as a consultant with water utilities in planning and design of water systems, but only first heard of the issue of pharmaceutical contaminants about a year ago while attending a conference.
Back at Tulane, he found some undergraduate students who were interested in the issue and directed them through a literature search. "We found limited information, but it was based on current research," Boyd said. Most of the work had been done in Europe. One group of researchers was looking for a herbicide contaminant when a compound they couldn't identify kept appearing. It turned out to be clofibric acid, a metabolite of the active ingredient in a drug commonly taken by those with heart disease.
Upon further investigation, those researchers found that the same compound had been detected in 1977 by researchers looking at river water in Missouri. Boyd decided to team up with Deborah Grimm, analytical chemist and director of Tulane's Coordinated Instrumentation Facility (CIF), to look at water samples from the Mississippi River and Lake Pontchartrain.
The team began preliminary field work with undergraduate students this past spring and summer, but only analyzed for three compounds. There are many more compounds that could be tested for, but doing so is extremely time-consuming. So Boyd brought postdoctoral researcher Siddhartha Mitra onto the team. The team's immediate task is to develop a rapid and reliable method for detecting a number of PPCP compounds using available analytical tools.
Boyd's team currently is developing experimental methods to isolate active ingredients in some of the most commonly used drugs such as analgesics (found in Aleve, Tylenol and Motrin), antihistamines, contraceptive medication, antibiotics, antidepressants such as Prozac, and antiseptics. One of the target antiseptics is triclosan, commonly found in toothpaste, children's plastic toys and soap. Triclosan has been linked to the evolution of antibiotic-resistant superbugs.
The work is being conducted in a sparkling new lab in the Israel Environmental Sciences Building, complete with a brand-new gas chromatograph, which is a sophisticated instrument that can measure miniscule levels of substances. The CIF also has provided researchers with access to additional analytical equipment. "This is a great laboratory and great equipment," Boyd said. "I feel very fortunate."
His work is currently being supported by the Tulane-Xavier Center for Bioenvironmental Research, but he has also applied for two grants from the Environmental Protection Agency and is hopeful that these will come through. The EPA has already recognized him as one of only a relatively few investigators who are conducting research on PPCP contamination in the environment.
"We're ahead of the game," Boyd said. "We have to answer a lot of questions. Are pharmaceutical contaminants pervasive in the environment? Do they pose a risk to humans as well as to the environment? If the answers to those questions are yes, then the next issue is treatment. But I'm hedging that it's going to be an issue, and we'll be looking at how to treat for it."
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