INFORMATION BRIEF
Minnesota House of Representatives
Research Department
600 State Office Building
St. Paul, MN 55155
John Helland, Legislative Analyst
651-296-5039 December 2006
Endocrine Disrupters as Emerging
Contaminants in Wastewater
Endocrine disrupters are being discovered in wastewater across the nation.
Scientists believe that these compounds may have detrimental effects on humans.
This information brief explains endocrine disrupters, how they can affect animals
and humans, where they are being discovered in wastewater, and how the issue
may be addressed.
Endocrine Disrupters and Their Effects
The term “endocrine disrupters” generally means the synthetic chemicals and natural plant
compounds that may affect the endocrine system—the communication system of glands,
hormones, and cellular receptors that control the body’s internal functions. Many of these
disrupters have been associated with developmental, reproductive, and other health problems in
wildlife and laboratory animals.
Some medical and scientific experts suggest these compounds may affect humans in similar
ways. Endocrine disrupters alter hormonal functions through several means:
mimicking the sex steroid hormones estrogen and androgen by binding to hormone
receptors, or influencing pathways
blocking, preventing, and altering hormonal binding to hormone receptors, or
influencing pathways
Copies of this publication may be obtained by calling 651-296-6753. This document can be made available in
alternative formats for people with disabilities by calling 651-296-6753 or the Minnesota State Relay Service at
711 or 1-800-627-3529 (TTY) for assistance. Many House Research Department publications are also
available on the Internet at: www.house.mn/hrd/hrd.htm.
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Endocrine Disrupters as Emerging Contaminants in Wastewater Page 2
altering production and breakdown of natural hormones
modifying the making and function of hormone receptors
Endocrine Disrupters in Wastewater
The use and disposal of pharmaceuticals entering river and sewer systems can lead to endocrine
disrupters. This may be related to the growing number of antibiotics, painkillers, and
antidepressants in the population; prescription drug sales increased by an annual rate of 11
percent between 2000 and 2005.
The two largest sources of pharmaceuticals entering our wastewater treatment systems are from
hospitals and homeowners. They enter the sanitary sewer primarily through excretion of
partially metabolized pharmaceuticals by the human body, and the disposal of unused or expired
medications down the drain or toilet.
Pharmaceuticals also enter surface waterways from the following sources:
wastewater treatment plants that treat household, industrial, and business wastewater
industrial wastewater discharges
commercial animal feedlot operations
surface application of manure and biosolids
Wastewater treatment plants are designed to remove conventional pollutants, such as suspended
solids and biodegradable organic compounds, but they are not designed to remove low
concentrations of synthetic pollutants, such as pharmaceuticals. A United States Geological
Survey (USGS) monitoring study of waterways in 2002 found that 80 percent of the surveyed
samples contained some pharmaceuticals, as well as fertilizers and flame-retardants.
The literature says pharmaceuticals probably have been in the environment for as long as we’ve
been using them. They are being discovered now because analytical methodology has recently
been developed that is sensitive at the parts-per-trillion level and lower. Increased detection has
led to questions about risks to humans:
What happens when organisms are exposed to multiple chemicals at the same time?
What happens when chemicals bioconcentrate in living creatures or accumulate in
sediment?
Some of the drugs in our waterways act upon more than one hormonal pathway. Some may end
up in humans through multiple exposures (antibiotics through food and water); and exposure to
mixtures of contaminants may lead to an adverse effect using one particular recipe. As medical
doctor Marc Taylor of Connecticut has said in studying the issue, the problem is only going to
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Endocrine Disrupters as Emerging Contaminants in Wastewater Page 3
get worse as the population ages: “We’ll have to rely on the health of the fauna in our rivers to
get hints about the consequences to people. The fish and amphibians are our canaries.”
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The Situation in Minnesota
The Minnesota Pollution Control Agency (MPCA) has been working with the USGS since 2000
to investigate the significance, sources, and occurrence of compounds with endocrine-disrupting
activity in Minnesota’s rivers and waste streams. Since 2004, both agencies also have an
interagency agreement with a professor from St. Cloud State University to do further work.
The projects to date have helped identify the most common chemical compounds and the ones
most likely to pose the highest risk to aquatic organisms through negative effects to reproduction
and even increased mortality.
The interagency agreement is conducting the first longitudinal study in the United States, which
will assess biological integrity and endocrine effects in four species of fish and chemical
exposures at 40 locations along the Mississippi River from Bemidji to the Iowa border. The
study will provide data on the extent of inter-sex along the river and by species of fish, along
with links between abnormal physiology and chemical presence. (Inter-sex is an abnormal
condition where testis have ovarian cells and structures.)
Work conducted by the USGS alone has shown that smallmouth bass in the Mississippi and
other rivers can have a high occurrence of inter-sex. A current field study at a major
metropolitan wastewater plant is examining effects in native fish species.
Waste pharmaceuticals in Minnesota may be classified as hazardous waste by either federal or
state rules. The hazardous waste pharmaceuticals comprise up to 20 percent of all
pharmaceuticals, but households are exempt from the classification. If a drug is not classified as
hazardous, it is treated as infectious or biohazardous waste and is sterilized before landfill
disposal.
Pharmaceuticals may be sewered in wastewater treatment plants under certain conditions, but
this is not encouraged because the disposer has to undergo certain procedures before the
pharmaceuticals are disposed of.
The generator of a waste has the responsibility to determine whether a waste is hazardous or not.
However, for pharmaceuticals and other endocrine disrupters, wastewater treatment plants
remove and treat only up to 50 percent of organic contaminants depending on the type and the
treatment system. The remainder is passed through downstream.
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Elizabeth Royte, “Drugging Our Waters,” OnEarth, 28 (Fall 2006): 31.
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Endocrine Disrupters as Emerging Contaminants in Wastewater Page 4
Possible Future Initiatives
Initiatives to prevent contamination by endocrine disrupters can range from aggressive public
education efforts to more costly regulation and enforcement. Many regulations on hazardous
wastes and wastewater treatment systems have not been updated since the late 1970s, nor kept
pace with the growing number of chemical compounds in the marketplace that should be
watched for regulation. Health care providers often become confused about which
pharmaceuticals may be hazardous or not, and how they should be disposed.
A strong public education program may be a way to alleviate concern over hazardous
pharmaceuticals and also can be a tool to reduce the amount of medications that are flushed into
the sewer system. Recommendations have included a labeling program like ones used to educate
consumers about household pesticides. Some experts say the best approach is to remove toxic
chemicals at the source rather than after disposal; take-back programs by the manufacturers of
unused products would be a cost-effective solution.
Communities could add pharmaceuticals to their household hazardous waste collection
programs, where consumers drop off the materials at designated sites once or twice a year.
On the federal level, consumer and environmental organizations could encourage federal
regulatory agencies to consider water quality impacts of toxic drugs as a regular component of
their decision-making authority. State agencies could establish a more formal communication
and recommendation process for pharmaceuticals between their hazardous waste and municipal
wastewater managers. They also could discourage public wastewater treatment plants from
approving any sewering of pharmaceutical hazardous wastes that are known to be toxic.
Further Information
For more information about endocrine disruptors, see the following resources:
Tom Arrandale, “Prozac in the Water,” Governing Magazine 19: 12 (September
2006): 56-58.
Gay Daly, “Hundreds of Man-Made Chemicals,” OnEarth 27: 4 (Winter 2006): 20-
27.
David Ewing Duncan, “The Pollution Within: Our Toxic Homes,” National
Geographic 210: 4 (October 2006): 116-135.
Minnesota Pollution Control Agency, “Healthcare, Hazardous Waste, and
Wastewater,” slide presentation (September 2006).
Elizabeth Royte, “Drugging the Waters,” OnEarth 28: 3 (Fall 2006): 26-31.
For more information about environmental protection, visit the environment and natural
resources area of our web site, www.house.mn/hrd/issinfo/environ.htm.
