Microconstituents in Water
- What are the microconstituents?
- Where are microconstituents found?
- Why are we finding these compounds
in water?
- What do the data show?
- How do these concentrations
compare to normal doses of medications?
- Is it surprising that we are
finding these compounds?
- Why must we protect other
organisms in the environment?
- Can we reduce the amount of the
microconstituents released to the environment?
- How should I dispose of unused
medications?
- Is my drinking water safe?
- Should I drink bottled water?
- Should I install a water treatment device in my
home?
- Is reclaimed water safe?
- Is additional research needed?
- How will research results be used?
What are the microconstituents?
Microconstituents, sometimes known as “emerging pollutants of concern,”
are chemicals found in a wide array of consumer goods, including
pharmaceuticals and personal care products. Some of the microconstituents
are considered to be “endocrine disrupters” (compounds such as synthetic
estrogen, PCBs, dioxin, and some pesticides that may interfere with or
modify hormone processes within an organism). ...back to
top
Where are microconstituents found?
Microconstituents may be found in very low concentrations in surface
water, ground water, domestic wastewater, industrial wastewater,
agricultural runoff, reclaimed water, and other waters. Many of these
compounds also may be found in soils and in the air. They are a fact of
modern, industrialized living. ...back to top
Why are we finding these compounds in water?
With the advancement of scientific laboratory methods, it is now
possible to identify and measure many more compounds in very low
concentrations. We can now detect compounds in the environment even as
their concentrations may be declining with improved waste management
practices. ...back to top
What do the data show?
In a 2002 study
the U.S. Geological Survey (USGS) sampled for 95 compounds at 139
locations in 30 states (generally “worst case” sites where
concentrations would be expected to be higher). One or more
microconstituents were detected at 80 percent of the sampling locations
with a median number of 7 compounds found. (Florida locations were: one
site on the lower Suwannee River with 12 compounds found, and another on
the upper Peace River with 15 compounds found.) Four classes of
compounds accounted for 86% of the total concentration of the
microconstituents measured – detergent metabolites (36%), steroids
(21%), plasticizers (20%), and non-prescription drugs (9%). Other
classes of compounds each contributed less than 2% of the total
concentration of the microconstituents. ...back to top
Of the 30 microconstituents detected most frequently in the USGS
study, 9 had median concentrations between 0.0001 and 0.001 mg/L (parts
per million), and the other 21 compounds had median concentrations less
than 0.0001 mg/L. Of the 95 compounds, 19 had median concentrations less
than detection. Fourteen have drinking water standards or human health
advisory levels and were detected at levels generally orders of
magnitude less than the standard or health advisory levels. The USGS
noted that aquatic toxicity studies had been conducted for 53 of the 95
compounds studied. The median concentrations found in the USGS sampling
generally were orders of magnitude less than the toxic values reported
in the referenced toxicity studies.
(See
http://toxics.usgs.gov/pubs/OFR-02-94 for the full USGS report.)
...back to top
How do these concentrations compare to normal
doses of medications?
Acetaminophen, a major ingredient in
nonprescription pain medications, commonly is taken in doses of 650 mg.
In the USGS study, this compound was found at a median concentration of
0.00011 mg/L. At this concentration, a person would have to drink nearly
6 million liters of water to equal a single 650-mg dose of
Acetaminophen. Ibuprofen is another leading pain medication that is
commonly taken in doses of 400 mg. The median concentration found in the
USGS study was 0.0002 mg/L. Lincomycin, an antibiotic, is normally
administered in doses of 500 mg. The USGS study reported a median
concentration of 0.00006 mg/L. Other studies confirm that these
compounds are found at concentrations that are orders of magnitude less
than normal doses. ...back to top
Is it surprising that we are finding these
compounds?
No. These compounds are associated with human
activity and scientists are now actively looking for them. Many of these
compounds are used to enhance our quality of life by protecting human
health, improving consumer goods, and optimizing agricultural
production. It is inevitable that small amounts of these compounds will
be released to the environment. It is also likely that these compounds
have been in surface waters for decades and, without analytical methods
to enable their identification and quantification, have remained
undetected until recently. ...back to top
Why must we protect other organisms in the
environment?
While considering human health, protecting other
organisms in the ecosystem is essential. In the aquatic environment,
small organisms at the bottom of the food chain may prove to be the most
critical. Their small size means that they will likely be more sensitive
to lower concentrations of these materials than humans.
...back to top
Can we reduce the amount of the microconstituents
released to the environment?
Yes, at least in part, by
properly disposing of unused medications. Studies show that a
significant percentage of medications are not used and are discarded –
mostly by flushing down the toilet. ...back to top
How should I dispose of unused medications?
Do not flush them down the toilet or other drains. Put unused
medications in the trash. Make sure you follow the Department’s
guidelines for protecting your privacy and preventing misuse of
medications discarded in the trash. (See
www.dep.state.fl.us/waste/categories/medications/default.htm.)
...back to top
Is my drinking water safe?
Yes.
Compliance with current drinking water standards assures that public
drinking water sources are safe. Florida's drinking water utilities have
an exemplary track record in delivering safe, affordable, high-quality,
drinking water. There is no evidence that the concentrations of
microconstituents reported in recent studies pose a threat to drinking
water supplies. ...back to top
Should I drink bottled water?
This is a
personal decision. Bottled water is held to the same basic water quality
criteria as drinking water from the tap, although it does not have to be
monitored as extensively. It is likely that bottled water will contain
very small concentrations of some microconstituents, similar to those
that may be found in tap water. ...back to top
Should I install a water treatment device in my
home?
Again, this is a personal decision. Whether or not home
water treatment devices effectively remove microconstituents is largely
unknown. Data suggests a variable effectiveness, depending on the type
of device, its operation and maintenance. ...back
to top
Is reclaimed water safe?
Yes. There is
no evidence that low concentrations of the microconstituents pose
concerns for the range of water reuse activities practiced in Florida.
...back to top
Is additional research needed?
Yes.
Research has always been an integral part of water management.
Fortunately, research related to the microconstituents is underway and
yielding valuable information. Studies to define dose-response
relationships, understand the fate and transport of the
microconstituents in the environment, and evaluate treatment processes
are underway for a number of these compounds and recently for
combinations of these compounds. We have learned much about effective
water and wastewater treatment processes. Studies also have demonstrated
that rapid infiltration basins (a common reuse method) and passage
through soils are effective in reducing concentrations of the evaluated
microconstituents. Because of the very large number of chemicals
involved, it must be noted that we will never have complete knowledge,
but rigorous scientific investigations will make us better informed and
better protected. ...back to top
How will research results be used?
In
the future, research may identify needed regulations and controls.
Initially, this may involve the establishment of new drinking water
standards, an ongoing process that predates the identification of
microconstituents. New drinking water standards are established by
either the federal government or by the Florida Department of
Environmental Protection. If additional drinking water standards are
adopted, Florida’s ground water standards would automatically be updated
to be identical. Changes to ground water standards could dictate
additional controls in wastewater treatment and water reuse. Studies on
aquatic organisms could lead to refined surface water quality standards
and, in turn, possible refinements in industrial and domestic wastewater
programs and in the agricultural arena. The results also could lead to
the development of cooperative and voluntary initiatives, such as
pharmacies taking back unused medications for proper disposal. This is
how science and public health protection progress. Future refinements to
water quality standards and regulatory programs must be driven by sound
scientific principles and reasoned public policy choices.
...back to top
