Section 13: Unmonitored Chemicals

Observation

The Commission is concerned that the number of chemicals being monitored to establish the chemical integrity of the Great Lakes ecosystem is inadequate for that purpose.

Of particular concern are many unmonitored chemicals, especially pharmaceuticals, flame retardants, and high-volume chemicals, such as a new generation of biodegradable pesticides, which have the ability to dissolve in both water and fat and therefore often show unusual patterns of bioaccumulation and environmental degradation. The mix of chemicals, and potential to cause unknown harm in combination, adds further concern. Most of the environmental consequences of these chemicals, usually found at low concentrations, are unknown.

Discussion

The U.S. Environmental Protection Agency uses a list of 129 Priority Pollutants as part of its regulations under the U.S. Toxic Substances Control Act. Other lists of toxic substances address the contents of waste repositories, notably the CERCLA Priority List of Hazardous Substances, which contains 275 trackable pollutants.¹ There are also numerous Canadian toxic substances lists, including the Canadian Water Quality Guidelines for the Protection of Aquatic Life,² which lists 180 chemical substances, and other sources from which to make selections of additional chemicals to monitor for the purposes of establishing the chemical integrity of Great Lakes.

Yet the number of chemicals actually monitored, often as few as 30, is a very small subset of the total, with more intensive monitoring occurring in special cases (e.g. monitoring for heavy metals, pesticide residue screening) at infrequent intervals or one-time special efforts. There are also questions about how to select the chemicals to be monitored, and which additional chemicals to select. Questions surround the available methods for monitoring at low environmental concentrations on a mass production basis, and the availability of infrastructure to accommodate the monitoring (laboratories, vessels, sampling facilities, etc).

Several groups of unmonitored chemicals have caused specific concerns among citizens and scientists, including pharmaceuticals, flame retardants, and high-volume chemicals. A landmark study by the United States Geological Survey has recently documented the distribution and levels of some of these chemicals in water bodies, mainly in rivers of the United States.³ None of the chemicals in this study has a Specific Objective in Annex 1 of the Great Lakes Water Quality Agreement. Also, many of these chemicals do not fit into the category in Annex 1 of nondegradable, bioaccumulative and persistent. They are persistent, but usually biodegradable and not all of them are bioaccumulative. The mechanisms and rates of biodegradability often depend on specific environmental conditions, which are sometimes present, and sometimes not. Studies at sewage treatment plants have shown the need for special adaptations to ensure removal of these materials from treated wastewaters.⁴

Pharmaceuticals include antibiotics, growth hormones, contraceptive drugs, veterinary products, and pesticides for animals and household pets.⁵ Some of these chemicals have known endocrine disruption properties;⁶ others confer antibiotic resistance to certain bacteria.⁷ Some have high-volume use in agriculture and medicine. Recent attention has been paid to pharmaceutical residues in drinking water supplies.⁸

Many flame retardants are brominated organic compounds similar in structure to PCBs, and can have even greater toxicity than their chlorinated counterparts. Some have been appearing in waters and biota of the Great Lakes system where they have not been previously documented.⁹

There is also a new generation of biodegradable pesticides that have solubility both in water and adipose (fatty) tissue. Atrazine, a widely used pesticide, is one example. Because of their high volume usage, these pesticides may pose new kinds of challenges in terms of their environmental toxicology and effects.

Most of the environmental consequences of these chemicals, usually found at low concentrations, are unknown. Also, these chemicals are rarely found alone, and the mix of chemicals adds further concern.