More than a dozen waterways in Illinois are under a mercury advisory by the Illinois Department of Public Health.
The advisory suggests that pregnant and nursing women, women of childbearing age and children younger than 15 years old limit consumption of certain fish from the locations because of adverse effects of mercury on developing nervous systems, which could result in lower IQ, abnormal muscle tone and slowed motor function. In the extreme, mercury poisoning can also be deadly.
The suggested limit is generally one meal a month for those "sensitive populations" and once a week for other folks.
UI Professor Bob Hudson said in the article that a form of mercury called methylmercury is of particular concern because it mimics a natural amino acid the body needs, especially the bodies of growing children.
"When we eat (contaminated) fish, we absorb almost all that mercury," said Hudson.
Mercury in its basic, inorganic form, while toxic, isn't as readily assimilated in the body or in the food chain.
Some mercury exists in the environment naturally, but most of it is put there by man-made means, coal-fired power plants, waste incinerators and industrial operations such as metal smelting, for example.
The mercury rises into the atmosphere and returns in rain and other precipitation. When it lands in an anaerobic location â€” one with depleted oxygen levels where bacteria can work on it, a wetland or the sediments of a lake bed, for instance â€”â€“ it's converted to organic methylmercury. From there it gets into plants, zooplankton, fish, wildlife and humans.
Scientists test for methylmercury now using gas chromatography, a method of separating and identifying chemicals in a sample carried along by a gas pumped through the detection apparatus.
Analysis of methylmercury is expensive â€” $200 or more a sample, Hudson said.
Hudson, who needs to do a lot of such testing in his research, couldn't afford it at that price, which also limits the number and scope of environmental studies involving mercury in general. So he and Chris Shade, a former UI doctoral student, began working on an alternative.
They developed a process, which is being patented, starting with easier-to-produce liquid samples that separates methylmercury by taking advantage of the difference in its electrical charge.
The process, which Shade is commercializing, can test a sample about every seven minutes. It can detect methylmercury at levels below one part per trillion, roughly equivalent to a drop of ink in an Olympic-sized swimming pool.
"We can simplify the preparation of the sample and you can automate getting the sample into the system," Hudson said. They're working on automating the process now.
The goal is to make the tests less expensive and more common, both for their own research and for environmental monitoring purposes. That might allow full-blown surveys of lakes and rivers for methylmercury to provide a better idea of where contamination is a problem and how to remediate it.