The Great Lakes have faced various threats for years, from industrial pollution to invasive species, but another challenge worries many researchers these days — the emerging chemical threat.
It’s not just pesticides, as scientists are finding worrying levels of pharmaceutically active compounds such as anti-inflammatories, antibiotics, anti-epileptics, and beta blockers in lake water. As well, hormones, pesticides and alkylphenols have been identified as threats.
The Great Lakes
The five Great Lakes straddle the U.S.-Canada border. Heavy populations exist in some areas of the lakes while other locations are quite remote. Both countries have been monitoring pollution in the lakes in recent years.
- Lake Ontario: 19,529 square kilometres.
- Lake Michigan: 58,016 square kilometres.
- Lake Huron: 59,596 square kilometres.
- Lake Erie: 25,744 square kilometres.
- Lake Superior: 82,103 square kilometres.
These products and medicines flushed down toilets and dumped into sinks are not stopped at water treatment plants, which are not geared to deal with them.
A new report prepared for the International Joint Commission by two Windsor, Ont., researchers has outlined the threats the chemicals pose. The International Joint Commission was formed by the U.S. and Canadian governments to find solutions to problems in the Great Lakes Basin.
The compounds "are receiving attention due to their potential adverse effects on animals and humans at low levels of exposure," said the report, co-authored by Merih Otker Uslu and Nihar Biswas of the University of Windsor. They sound a warning later in the report, which is a review of data collected from 2007-11.
"The toxic effects on aquatic organisms, alterations on the reproductive system of aquatic organisms and the promotion of the development of resistant bacterial strains representing a health risk to humans, are among the adverse effects of these compounds.
"Although chemicals of emerging concern have been detected in different environmental compartments for a longtime period, their environmental releases have not been completely regulated by the regulatory communities in the United States and Canada."
Uslu and Biswas called for a comprehensive risk assessment of each chemical of emerging concern.
Sewage treatment plants are not designed to handle pharmaceutical substances, the report suggests, leading to a "vast" array of drugs in varying levels in the Great Lakes.
"The main concern regarding the presence of pharmaceutical residues in the aquatic environment has been focused on antibacterials which may promote the development of resistant bacteria strains representing a health risk to humans," said the International Joint Commission report.
Substances such as antidepressants, antibiotics, and steroid hormones that eventually make it into groundwater that is then tapped into a house "may also pose adverse effects on humans." The levels of pharmaceuticals found were quite low, and the study does not delve into how much water needs to be consumed before health is affected.
Levels of caffeine have been found as well.
The warning about pesticides in the lakes is simple and disturbing: "Many pesticides are suspected of being endocrine disruptors which can cause sexual abnormalities and reproductive failure."
Elevated levels of pesticides are found in the Great Lakes during late spring and summer when agricultural activities are in full bloom. The studies considered by Uslu and Biswas found elevated levels of pesticide in watersheds that flow into the lakes, passing golf courses and farms on the way.
In one study, seven great blue heron colonies were sampled in the St. Lawrence River in 2001 and 2002. Samples were analyzed for 21 pesticides. More than half of these 21 pesticides were detected in about 50 per cent of the samples, the study stated.
The level of pesticides in the lakes, as well as the type of chemical, depends on where the test samples are taken. The Humber River watershed has higher levels of the chemical atrazine than the Don River watershed because it includes more agricultural area.
Flame retardants are chemicals that can be added to paint or other materials.
"These substances are highly toxic and persistent in the environment. Due to high lipophilicity and stability, they have the potential for accumulation in sediments and bioaccumulation in wildlife," said the report.
Some flame retardants have chemical structures similar to PCB, and "are also considered potential endocrine disruptors."
Some types of retardants originate from manufacturing processes and can come from the air.
Synthetic musk fragrances
The musks are used in a number of products, including perfumes, cosmetics, detergents and cleaning products.
"Due to their lipophilic nature, synthetic musks could not be effectively removed in sewage treatment facilities and are retained in sewage sludges," said the report.
Among fish taken in Chicago, the chemicals were found in all of the samples.
"Bisphenol A is a well-known plasticizer used to make polycarbonate plastics and epoxy resins. It is a highly persistent endocrine disruptor and therefore subjected to risk assessment studies by regulatory authorities around the world," said the report.
It has been widely detected in drinking water, in Detroit and Windsor, Ont., and in the water of 17 other Ontario communities.
Bisphenol A was declared a toxic substance by Canadian authorities in October 2010. It does not pose a danger to human health though through food packaging uses, Health Canada said.