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Light Pollution:

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Health Association Viewpoints on Light Pollution affecting Human Health

There are many organizations and web pages out there that strive to collect money from you to find a cure to breast cancer. This page is not one of them. It is the philosophy of these pages to help prevent health problems by raising the awareness of a man-made factor that can increase their risk of occurring, of which seems to include certain cases of cancer. Just as there are many different paths that one can take to get to a particular designation, there are many possible sources or factors that can cause errors in our cell's genetic coding that lead to cancer. Understanding those sources and avoiding should be our first step to maintain health.

This particular page catalogs the viewpoints regarding this issue of some professional health associations or organizations. It is by no means a complete or selected list. If I have missed a viewpoint from such an association, the fault is mine alone in researching them.

The problem is that light pollution is one factor that is increasingly hard to avoid due to its pervasiveness in society and the fact that it is growing exponentially. It is one factor that we inflict upon each other, near and far. It is one factor that we pay each and every night to make. And it is one factor that anyone can help correct.

An even weak amounts of light impedes our pineal gland from creating the beneficial melatonin. Without this signaling hormone, other glands produce their hormones unchecked, which lead to ever greater breast cancer rates. In our industrialized societies, light pollution or light at nights becomes harder and harder to avoid, even if you knew to avoid it. It is a common impression is that it is only light. And this apathetic acceptance may be a reason for the ever greater breast cancer rates in industrialized societies. Technology is only good when it is properly used. So while we may herald modern and super-lit technological society, when it threatens our health, it needs to be called into question, even if it is just light.

Summary: Does light pollution directly cause cancer? No. Unlike in astronomy, light itself is not the problem.

It is our biological reactions to the light that is the problem.

The next time that someone says to you that it's just light, tell them: no, light is our biological triggering input that suppresses a cascade of subtle, health improving functions that should naturally and nightly occur in our bodies. These functions include those that promote better sleep, fight depression, fight obesity, and consume free radicals which damage DNA and cells and so negate some risk factors for certain cancers. It is NOT just light.

Because more of us are sleeping in overly lit nights, light pollution has been found to be a missing, aggravating factor that suppresses melatonin levels in humans at night. This change pulls out the stops to cancer cell growth. The hormone melatonin normally suppresses cancer cell growth and can even cause cancer cell death. It does this by inhibiting the sex ovaries from growing too fast and from releasing hormones can cause breast tissue cells to multiply faster. This would increase the chance that they become cancerous. The papers mentioned below examine this effect in detail. Once you are done here, you may want to head over to our Prevent Light Pollution page to find steps you can take to end this problem to yourself and others.

Some Official Associations Respond to Health Hazards by lights at night

Back to Light Pollution vs. Human Health

American Cancer Society adds night work as a breast cancer risk factor

The American Cancer Society includes night work as being a cancer risk factor. Their web page has the following statement:

Night Work

Several studies have suggested that women who work at night -- for example, nurses on a night shift -- may have an increased risk of developing breast cancer. This is a fairly recent finding, and more studies are looking at this issue. Some researchers think the effect may be due to changes in levels of melatonin, a hormone whose production is affected by the body's exposure to light, but other hormones are also being studied.

This came from's page that had its Last Medical Review: 08/23/2012, Last Revised: 02/26/2013

Note that while they now include this statement under the heading of "Factors with uncertain, controversial, or unproven effect on breast cancer risk", they do not state that the linkage is disproven. There is a long hidden chain of actions, effects and counter effects between some lights on at night and someone's instance of breast cancer and there are other factors involved, so any linkage is not a slam dunk proof. The ACS is rightly cautious about declaring what is the cause of any case of cancer. They have stated that two out of three cases of breast cancer tumors have receptors that make them hormone sensitive, either estrogen (ER-positive) and/or progesterone (PR-positive). In such cases it seems, by the papers mentioned in these pages, that these are cases of breast cancer where efforts that are taken to ensure that nights are dark can beneficially aid in combating the cancer.

Even though I prefer to be more metric than this, this next quote is just too fitting to pass by. To those that do not know what an ounce is: one "ounce" is equal to 28.34952 grams and that there are sixteen "ounces" in a "pound".

An ounce of prevention is worth a pound of cure.

Benjamin Franklin

In short, this effort of correcting lights at night is an example of an educated or informed prudence or simply following a wise precautionary principle. Human or other life on this planet did not evolve with artificial lights continuously on at night. To assume that there would be no consequence to our health by their introduction to our environment is either blind ignorance or intentional apathy. This thinking to the above mentioned guiding precautionary principle comes from the 1998 Wingspread Conference on the Precautionary Principle that was convened by the Science and Environmental Health Network.

They wrote then:

The release and use of toxic substances, the exploitation of resources, and physical alterations of the environment have had substantial unintended consequences affecting human health and the environment. Some of these concerns are high rates of learning deficiencies, asthma, cancer, birth defects and species extinctions; along with global climate change, stratospheric ozone depletion and worldwide contamination with toxic substances and nuclear materials.

We believe existing environmental regulations and other decisions, particularly those based on risk assessment, have failed to protect adequately human health and the environment - the larger system of which humans are but a part.

We believe there is compelling evidence that damage to humans and the worldwide environment is of such magnitude and seriousness that new principles for conducting human activities are necessary.

While we realize that human activities may involve hazards, people must proceed more carefully than has been the case in recent history. Corporations, government entities, organizations, communities, scientists and other individuals must adopt a precautionary approach to all human endeavors.

Therefore, it is necessary to implement the Precautionary Principle: When an activity raises threats of harm to human health or the environment, precautionary measures should be taken even if some cause and effect relationships are not fully established scientifically.

In this context the proponent of an activity, rather than the public, should bear the burden of proof.

The process of applying the Precautionary Principle must be open, informed and democratic and must include potentially affected parties. It must also involve an examination of the full range of alternatives, including no action.

The Wingspread Conference on the Precautionary Principle was convened by the Science and Environmental Health Network.

Follow the link to their Conference Page at: published a news archive article about the study at Hormone Melatonin Slows Breast Cancer - Bright Light at Night Linked to Increased Cancer Risk by Daniel J. DeNoon, in July 14, 2003. The article quotes Dr. Blask as saying that Nighttime melatonin is a relevant anticancer signal to human breast cancers. Ninety percent of human breast cancers have specific receptors for this signal.

IARC Monographs Evaluates the Carcinogenic Risks of Shiftwork to Humans

Source: (Vol. 98; in preparation, pg 22)

Source: (Vol. 98; in preparation, pg 7)

The International Agency for Research on Cancer (IARC) is part of the UN's World Health Organization. The IARC Monographs identify environmental factors that can increase the risk of human cancer. These include chemicals, complex mixtures, occupational exposures, physical and biological agents, and lifestyle factors. National health agencies use this information as scientific support for their actions to prevent exposure to potential carcinogens. The IRAC Monographs on the Evaluation of Carcinogenic Risks to Humans Vol. 98, currently in preparation, classifies shiftwork that involves circadian disruption as a probable carcinogenic to humans, in their Exposure circumstances section.

This classification puts circadian disrupting shift work in the same carcinogenic classification as UV radiation exposure from tanning beds, Kaposi's sarcoma herpesvirus/human herpes virus, inorganic lead compounds, creosotes and diesel engine exhaust.

American Medical Association UNANIMOUSLY passes Resolution 516 to combat the effects of Light Pollution!
AMA Logo


Source Link: AMERICAN MEDICAL ASSOCIATION HOUSE OF DELEGATES Annual Meeting 2009 - Resolution: 516. See page 40.

[ Note: the full copy of the original resolution appears below. The active source link now only has their closing RESOLVED statements. ]

Introduced by: Connecticut, Maine, Massachusetts, New Hampshire, Rhode Island, and Vermont Delegations

Referred to: Reference Committee E (Martin G. Guerrero, MD, Chair)

Whereas, Our AMA has long advocated for policies that are scientifically sound and that positively influence public health policy; and
Whereas, We in the AMA have an opportunity to influence and promote legislation at both the national and state level on energy savings through a reduction in light pollution; and
Whereas, Light pollution is increasingly recognized as a waste of energy and a public safety issue; and
Whereas, It has been calculated that over 10 billion dollars in wasted energy could be saved with the use of full cutoff streetlights; and
Whereas, Emitted glare light is wasted light and accounts for about 40% of the light emitted by standard streetlights (cobras), it is therefore a significant source of wasted electricity, and this contributes to excess carbon dioxide production and possibly global warming; and
Whereas, Numerous states (Arizona, Arkansas, Connecticut, Delaware, Hawaii, Maine, Michigan, Montana, New Mexico, Rhode Island, Texas, Vermont, Virginia, Wyoming), many municipalities, and several countries have now enacted Light pollution control measures; and
Whereas, Light pollution control legislation is being proposed in Congress; and
Whereas, Streetlight glare causes decreased nighttime visibility by pupil constriction, and thus leads to diminished nighttime visibility and creates a safety hazard 1,2,3,4,5,6,7; and
Whereas, Many older citizens are significantly affected by glare as the eye ages, leading to unsafe driving conditions 8,9,10,11,12,13,14,15; and
Whereas, Glare light is also light trespass and is intrusive and unwanted in households and dwellings; and
Whereas, Light trespass has been implicated in disruption of the human and animal circadian rhythm, and strongly suspected as an etiology of suppressed melatonin production, depressed immune systems, and increase in cancer rates such as breast cancers 16,17,18,19,20,21,22; and
Whereas, Light trespass disrupts nocturnal animal activity and results in diminished various animal populations' survival and health 23; therefore be it
RESOLVED, That our American Medical Association advocate that all future outdoor lighting be of energy efficient designs to reduce waste of energy and production of greenhouse gasses that result from this wasted energy use (New HOD Policy); and be it further
RESOLVED, That our AMA support light pollution reduction efforts and glare reduction efforts at both the national and state levels (New HOD Policy); and be it further
RESOLVED, That our AMA support efforts to ensure all future streetlights be of a fully shielded design or similar non-glare design to improve the safety of our roadways for all, but especially vision impaired and older drivers. (New HOD Policy)

Fiscal Note: Staff cost estimated at less than $500 to implement.
Received: 03/30/09
1 US Department of Transportation, Phase II of ENV project, Chapter 3: Discomfort and Disability Glare Study, 2005
2 Schieber, F, Kline, DW, Kline,TJB, Fozard, JL (1992). Contrast Sensitivity and the visual problems of older drivers. Warrendale, PA . Society of Automotive engineers (SAE Technical paper No. 920613)
3 Olsen, PL, and Aoke, T, (1989) The measurement of Dark Adaption level in the presence of glare, Ann Arbor, MI: Transportation Research Institute, University of Michigan, (report No. UMTRI-89-34).
4 Adams, AJ, Wong, LS, Wong, L, and Gould, B. (1988). Visual Acuity Changes with age: Some new Perspectives. American Journal of Optometry and Physiological optics. 65, 403-406.Virginia Tech Transportation Institute (2007), Development of a Uniform discomfort/Disability glare metric for roadway lighting
5 Brabyn, J.A., & Haegerstrom-Portnoy, G., & Schneck, E. (2000). Visual impairments in elderly people under everyday viewing conditions. Journal of Visual Impairments & Blindness, 94 (12), 741-755.
6 Guirao, A., & Gonzalez, C., & Redondo, M., & Geraghty, E., & Norrby, E., & Artal, P. (1999). Average Optical Performance of the Human Eye as a Function of Age in a Normal Population. Investigative Ophthalmology & Visual Science, 40 (1), 203-213.
7 Ngai, P., & Boyce, P. (2000). The effect of overhead glare on visual discomfort. Journal of the Illuminating Engineering Society, 29 (2), 29-38.
8 Owsley, C, et al. Impact of Cataract Surgery on Motor Vehicle Crash Involvement by Older Adults, JAMA 2002;288:841-849.
9 Rubin GS, Adamsons IA, Stark WJ. Comparison of acuity, contrast sensitivity, and disability glare before and after cataract surgery. Arch Ophthalmol. 1993;111:56-61.
10 Elliott DB, Bullimore MA. Assessing the reliability, discriminative ability, and validity of disability glare tests. Invest Ophthalmol Vis Sci. 1993;34:108-119.
11 Kloog, Haim, Stevens, Barchana & Portnov, Light at Night Co-distributes with incident breast but not lung cancer in the female population of Israel, Chronobiology International 25(1): 65-81 (2008)
12 Schernhammer ES, et al. (2001) Rotating Night Shifts and the risk of Breast Cancer in the Nurse's Health Study. J National Cancer Institute. 93: 1563-1568
13 Schernhammer ES et al. (2006) Night Work And the risk of Breast Cancer. Epidemiology 17:108-111
14 Pauley, SM (2004) Lighting for the Human Circadian Clock: Recent Research indicates that Lighting has become a Public Health Issue Med. Hypotheses 63:588-596
15 Hahn, RA (1991) Profound Bilateral Blindness and the incidence of Breast Cancer Epidemiology 2:208-210
16 Feychting, M et al (1998) Reduced Cancer Incidence among the Blind Epidemiology 9:490-494
17 Brainard, GC et al, (2001) Action Spectrum for Melatonin Regulation in Humans: Evidence for novel Circadian Photoreceptor J. Neurosci 21:6405-6412
18 Blask DE et al, (2005) Melatonin-Depleted Blood from Pre-menopausal Women exposed to Light at Night stimulates growth of human-breast cancer xenografts in nude rats Cancer Research 65:11174-11184
19 McGwin G, Chapman V, Owsley C. Visual risk factors for driving difficulty among older drivers. Accid Anal Prev. 2000;32:735-744.
20 Elliott DB, Bullimore MA. Assessing the reliability, discriminative ability, and validity of disability glare tests. Invest Ophthalmol Vis Sci. 1993;34:108-119.
21 Vos JJ. Disability glare: a state of the art report. CIE Journal. 1984;3:39-53.
22 Owsley, Cynthia et all. Visual Risk Factors for Crash Involvement in Older Drivers With Cataract, Arch Ophthalmol. 2001;119:881-887
23 Gray, Robert. Predicting the effects of Disability Glare on Driving Performance, Proceedings of the forth International driving Symposium on Human Factors in Driver Assessment, Training and vehicle Design.

Department of Physics
Florida Atlantic University
Boca Raton, Florida
E-mail: evandern at fau dot edu
Phone: 561 297 STAR (7827)

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