The Jury is Still Out on Microconstituents
A recent TV news story in New York City reported on a Stony Brook University study that found winter flounder in Jamaica Bay outside NYC are over 90% feminine as the result of compounds entering the Bay from the NYC wastewater treatment plants.[1] The study reported that nonylphenol ethoxylates found in the Bay sediments and water may be the cause. Other compounds such as estrogens from use of birth control pills (which have more potent estrogencity factors) could also be contributing to the impact on flounder. This is one of many news stories highlighting the presence of low levels of human-produced chemicals in the environment and the increased media attention bespeaks a growing public anxiety toward this phenomenon.
Microconstituents, formerly known as Compounds of Emerging Concern, are defined by the Water Environment Federation as natural and manmade substances including elements and both inorganic and organic chemicals, detected in water and the environment for which a prudent course of action is suggested for the continued assessment of the potential impact on human health and the environment. This broad range of compounds includes: human and veterinary drugs; pesticides and industrial chemicals; personal care products; musk fragrances and nanoparticles. Approximately 100 of these compounds are considered known endocrine disruptor compounds (EDCs), which may interfere with hormone processes in both wildlife and humans. The EDCs include naturally occurring and synthetic steroid hormones, organohalides, some metals and alkylphenols.
Microconstituents are getting into the environment through a variety of sources such as agricultural runoff, industrial discharges, and disposal and human excretion of medicine in hospitals, nursing homes, and households. Wastewater sewers provide conduits to municipal treatment plants and then to rivers and other water bodies. As more studies are done and the analytical methods are developed and refined, we can expect more reports and findings that microconstituents are ubiquitous in the environment. The existing transport models and risk assessment protocols need to be re-evaluated to determine how best to model these compounds in wastewater systems and the environment.
It is unclear whether these compounds impact public health in drinking water. The World Health Organization has stated that “analysis of the human data by itself, while generating concerns, has so far failed to provide firm evidence of direct causal associations between low-level… exposure to chemicals with EDCs and adverse health outcomes.”[2] Other researchers have reported concerns about the potential human health impacts of polycyclic aromatic hydrocarbons (PAHs) and mixed of pesticides. Microconstituents are not regulated by the Environmental Protection Agency (EPA) or the Food and Drug Administration (FDA) at present. EPA held a meeting in Washington DC in late 2007 to discuss whether future regulation is warranted. Several drug take-back programs are in place around the United States with the goal to reduce the mass of microconstituents entering the environment. It remains to be seen what impact these programs will have on the environment, but they are one step in the overall management approach. In Europe, countries such as Germany have done extensive research and monitoring and have begun to develop regulations including the banning of some compounds.
What is clear is that more research is needed by WERF and other stakeholders. Collaboration is already occurring among the USGS, academia, utilities and pharmaceutical companies on projects to evaluate the fate of transport of microconstituents in wastewater treatment plants and receiving waters. The physicochemical properties of some of these compounds, such as partitioning coefficients, are different than other compounds such as PCBs and PAHs. These properties need to be evaluated on projects since they impact both partitioning to biomass in treatment plants and partitioning to sediment in receiving water.
Treatment technologies already exist to remove and destroy these compounds in wastewater and water treatment plants. Biological and advanced oxidation treatment technologies are well documented. However, cost/benefit analyses are needed to determine whether the increase in treatment costs to achieve non-detect concentrations are worth the risk reduction and benefits. We should keep in mind that some of these microconstituents provide significant benefits to society and improve our quality of life and health.
If history is any guide, public perception and concern will drive some of the decisions on control and treatment of microconstituents, as happened with clean up of the superfund hazardous waste sites. One of WEF’s goals is to provide education of its members and the public on this subject. In order to present the most accurate picture, further research and collaboration is needed between stakeholders in the United States, Europe and Asia. It is particularly important to advance the knowledge base on micro constituent transport and human health risks. The jury is still out on how to best manage and reduce the impact of these microconstituents on both public health and the environment. What we do know is that the WEF Microconstituent specialty conferences and publications such as this are small but important steps toward the realization of these aims.
Joseph G. Cleary, Issue Editor
HydroQual, Inc.
[1] “Female Flounders Rule Jamaica Bay.” Carolyn Gusoff. WNBC-4, New York City. July 25, 2007.
[2] “Global Assessment of the State of the Science of Endocrine Disruptors.” Ed. Terri Damstra, Sue Barlow, Aake Bergman, Robert Kavlock, Glen Van Der Kraak. World Health Organization, 2002. Ch.1, p.2. http://www.who.int/ipcs/publications/en/ch1.pdf