In this section:
Undesired Effects
What You Can Do
Did You Know
For More Information
Related Information:
Air Pollution
Animal Welfare
Leslie
Peltier, a well known amateur astronomer and author once wrote,
"The moon and the stars no longer come to the farm. The
farmer has exchanged his birthright in them for the wattage of
his all-night sun. His children will never know the blessed dark
of night."1
Peltier was referring to light pollution, or the
excessive use of light. Large industrial dairies are often
heavily lit 24 hours a day—making them visible for miles
in the nighttime sky. Their light can blot out clear views of
the rural nighttime sky, distract drivers passing by on
neighboring roads, spill unwanted light onto the property of
neighboring homes, and reduce property values by making the area
less attractive. Most importantly, light pollution is also a
major waste of energy, especially considering that many factory
farms use lights 24 hours a day.
Undesired Effects
But light pollution is not just annoying and wasteful -
it’s also hazardous to the health of farm animals, human
beings and even entire ecosystems. Since life evolved around
natural patterns of light and dark, artificial light can alter
animal and plant behavior. For instance, light pollution has
been found to disrupt the behavior of birds, aquatic animals and
insects. It can increase algae in nearby lakes and ponds, and it
affects seasonal patterns of plants and trees. 2
The heavy use of lights in dairy free stall barns and
drylots can also lead to heath problems for both cows and human
beings. Operators of industrial dairies often keep lights on for
eighteen or more hours a day in the free stalls and dry lots
where cows are confined. Increasing the number of hours a cow is
exposed to light is a way to manipulate the animal’s
internal clock and increase the amount of milk she produces.
That’s because exposure to light suppresses the secretion
of a hormone called melatonin. When there’s less
melatonin in the blood, that affects production of other
important hormones, like insulin growth factor-I (IGF-I), which
triggers the production of extra milk. In order to reap maximum
production from cattle herds, 18 hour-a-day lighting is now
standard practice on large factory dairy farms. 3
The problem is that melatonin - for cows, for
wildlife, and for humans and all other mammals - is a
powerful and critical hormone. For instance, melatonin levels in
the body can help determine when puberty begins. Studies have
found that heifer calves exposed to artificially long periods of
light grow faster and reach puberty faster. 4
Melatonin is also an important antioxidant that helps
maintain the body’s immune system. Exposing cows to 18
hours of lighting in free stalls can therefore contribute to a
vicious cycle: it increases a cow’s chances of becoming
sick, which in turn increases the chances that the dairy
operator will treat the animal with antibiotics and anti-virals,
which then risk getting passed on to humans in milk (or beef, if
the cow is slaughtered.) And as antibiotics get overused,
dangerous bacteria begin to mutate and become resistant to
certain drugs. 5
Light pollution may also pose more direct risks to
humans. Night light doesn’t just suppress melatonin in
cows, but in humans, too. In addition to strengthening your
immune system, melatonin also reduces your cholesterol and blood
pressure, benefits that are lessened with exposure to light at
night. Recent studies suggest that there may be a link between
lower levels of melatonin in women and the risk of breast
cancer, and some experts believe that light pollution should be
taken more seriously as a public health threat. 6
What You Can Do
- Hold CAFOs (confined animal
feeding operations) accountable.
If you live near a CAFO, talk to your neighbors and others in
the community also affected by light and other forms of
pollution. Share information that you can use to lodge a
complaint. Many local governments have nuisance laws and
environmental laws that govern the operations of CAFOs. Get to
know the people on your local zoning commission — they
can be great allies.
- Buy sustainable dairy products.
Support farmers that raise their animals without damaging the
night time environment. Visit your local Farmer’s Market where you can ask
the farmer directly about the farm’s light usage.
- Use the Eat
Well Guide to find farms, stores, restaurants, and bed &
breakfasts offering sustainable dairy and other animal products
in your area.
Did You Know?
- The human body produces melatonin
– a chemical that helps protect your body against cancer
– while in darkness. According to two studies published
last year in the Journal of the National Cancer Institute, if
the light coming in your bedroom window at night is at least as
strong as a streetlight, it may be detrimental to your health.
7
- Some groups view dark skies as a
natural resource akin to an old growth forest or wetlands,
worthy of protecting for its role in ecological balance.
- Nocturnal birds use the moon and
stars for navigation during their bi-annual migrations, which
can be disturbed by artificial light. 8
For More Information
- International Dark-Sky Association: The
mission of the International Dark-Sky Association (IDA) is
“to preserve and protect the nighttime environment and
our heritage of dark skies through quality outdoor
lighting.”
- Use Sustainable Table’s Shop Sustainable
section to learn more about where to get food from local farms,
and get the questions to ask the farmers you meet there.
Page last updated October 2008
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