Student Science
ENVIRONMENT & POLLUTION
https://student.societyforscience.org/article/artificial-sweeteners-pollute-streams/
Artificial
sweeteners
pollute streams
People excrete much of their foods’
fake sugar, which can end up
bathing fish and other aquatic life
BY JANET RALOFF 8:30AM, NOVEMBER 18, 2014
In the past few decades, diners have been turning increasingly to soft drinks
and foods sweetened with fake sugar. The idea is to get the sweet taste
without loading up on calories. But a new study finds an environmental cost
to these sweeteners: In short order, they can end up polluting lakes and
streams.
The human body tries to break down food into its raw materials. This helps
extract any calories as energy. It also gives tissues the raw materials they
need to grow. But our bodies largely ignore fake sugars. That’s why they
don’t get converted to fat. Instead, they “are excreted mostly unchanged
from the human body,” note Bikram Subedi and Kurunthachalam Kannan.
They work for the New York State Department of Environmental Health
Sciences in Albany.
After they are consumed, the artificial sugars are flushed out of the body and
down the toilet. From there they flow to a sewage treatment plant. The
purpose of these plants is to remove pollutants before the water is released
into the environment once more. But water-treatment plants don’t remove all
fake sugars from sewage equally well, the new data show.
Past studies have shown that water containing artificial sweeteners can harm
a plant’s ability to perform photosynthesis. Plants use this process to
produce food. Along the way, photosynthesis also releases oxygen into the
air. As water pollutants, fake sugars also can alter the movements and body
processes of water fleas. (These are not real fleas but rather teeny
crustaceans known as Daphnia magna). The tiny animals serve as food for
many fish. So fake sugars may not be safe for all organisms.
For their new study, Subedi and Kannan measured the amount of fake sugar
in sewage entering two local water-treatment plants. Later, these chemists
measured how remained in the water as it left those plants.
The treatment plants removed 75 percent of the aspartame in water. (This
sweetener is sold in blue packets as Equal). Those plants also got rid of 90
percent of the saccharin (sold in pink packets as Sweet'N Low).
But the plants didn’t do nearly as well with two other fake sugars. Ninetyeight percent or more of sucralose passed right through the cleanup plants
and out the other end, the study found. (This sugar substitute is sold in
yellow packets under the name Splenda.) This chemical could then flow into
rivers, lakes or the ocean. Treatment plants proved equally poor at removing
acesulfame. (Supermarkets sell it as Sunett or Sweet One. Some companies
also include it in sweetener blends, along with Splenda.)
Water-treatment plants had a hard time removing the excreted fake sugars
that dissolve especially well in water, such as Splenda and Sunett. That now
appears to explain why some studies have found traces of these fake sugars
not only in stream water but also in drinking water.
Subedi and Kannan’s new data appeared online November 3 in Environmental Science &
Technology.
Power Words
calorie amount of energy needed to raise the temperature of 1 gram of water by 1 °C. It
is typically used as a measurement of the energy contained in food.
crustaceans Hard-shelled water-dwelling animals including lobsters, crabs and shrimp.
Daphnia magna Also known as water fleas, these are actually small, freshwater
crustaceans. They are near the bottom of the food chain, serving as a major energy source
for many small fish.
excrete To remove waste products from the body, such as in the urine.
pollutant A substance that taints something — such as the air, water, our bodies or
products. Some pollutants are chemicals, such as pesticides. Others may be radiation,
including excess heat or light. Even weeds and other invasive species can be considered a
type of biological pollution.
saccharin A no-calorie sugar substitute.
sewage Wastes — primarily urine and feces — that are mixed with water and flushed
away from homes through a system of pipes for disposal in the environment (sometimes
after being treated in a big water-treatment plant).