by Aaron Nazarian
The genes we inherit from our parents play an important role in determining our health. Similarly, the environment we live in has a great impact on our health. So, do our genes or does the environment to which we are exposed have a greater influence on our health? There exists a complex interaction between inherited genes that make you vulnerable to a disease (genetic susceptibility) and environmental exposures. Together, this interaction between genes and environment determine whether we will be healthy or develop a certain disease. Some cancers, heart disease and diabetes run in families and may be caused by genes; however, more is involved than just our genes. Flawed genes are not the only source of most diseases and disorders. Our environment, using chemical products, eating and drinking habits, and exercise can be important. Research has found that most diseases have a non-gene trigger, meaning substances exist in our environment that together with an ineffective gene cause diseases. Many people may have flawed genes or genetic susceptibilities, but if the negative environment that is necessary to signal that flawed gene is not present, then that person may never develop that disease. Simply put by one scientist, "Heredity loads the gun and environment pulls the trigger."
Another recent study, in The New England Journal of Medicine, revealed that our environment has more bearing than genetics in determining whether a person will develop cancer. Accounting for approximately twice the risk of cancer than our genes, the environment we are exposed to has a far greater impact on our health than previously believed. One way our environment impacts our genes is by actually changing functional genes into ineffective genes. Natural substances from the environment can sometimes change a gene's code and cause a disease, even though no genetic susceptibility was present. Chemicals or X rays can also affect genes, especially if people are careless about how they handle these things. Smoking causes changes in the genes of our lungs and other places in the body. These poisons can affect the message that a gene sends to cells in order to tell them what to do, how to assemble, and how to grow. They can weaken the cell's way of correcting mistakes that can occur in the DNA (the chemical chain that carries our genes). Currently it's not very easy or feasible to change ones genes. However, it is very possible for people to change their individual environment, and the substances to which they are exposed. For example, eating at least five fruits and vegetables a day appears to reduce the risk of cancer and can compete with a gene that increases susceptibility to cancer. The more we are aware of our environment, the more we can control our health.
Carcinogens In Our Environment
A carcinogen is a substance that causes cancer or is believed to cause
cancer. Everywhere, a significant number of people are exposed to substances
that may lead to the formation of cancer in their body. Some common
carcinogens include asbestos, arsenic, certain molds and viruses, and various
types of radiation such as ultraviolet and x-rays. Carcinogens can be inhaled
(tobacco smoke), ingested (nitrites), or absorbed through the skin
(pesticides). It has been predicted that 30% of Americans will die of cancer
caused in part by environmental carcinogens before they reach the age of 74.
Through a procedure called the Ames test, scientist can check potential
carcinogens for their probability to damage DNA
and cause genetic mutations.
Most people are unaware of the number of carcinogens in our environment.
Congress in 1978 first ordered an annual report on carcinogens because many
cancers appear to be caused by exposure to substances in the environment
including the home and workplace, or from use of agents such as food
additives, pesticides or pharmaceuticals. It is only fair that people should
be informed of what in their environment could possibly be harming them. The
following is a list of known human carcinogens-agents, substances, mixtures or
exposure circumstances known to be human carcinogens. This list is part of the
US Government's 9th Annual Report on Carcinogens from the National Toxicology
Program (NTP).
US Government List of Known Human Carcinogens:
- Aflatoxins
- Alcoholic Beverage Consumption
- 4-Aminobiphenyl (4-Aminodiphenyl)
- Analgesic Mixtures Containing Phenacetin
- Arsenic and Certain Arsenic Compounds
- Asbestos
- Azathioprine
- Benzene
- Benzidine
- bis(Chloromethyl) Ether and Technical-Grade Chloromethyl Methyl Ether 1,3-Butadiene
- 1,4-Butanediol Dimethylsulfonate
- Cadmium and Cadmium Compounds
- Chlorambucil
- 1-(2-Chloroethyl)-3-(4-methylcyclohexyl)-1-nitrosourea (MeCCNU)
- Chromium Hexavalent Compounds
- Coke Oven Emissions
- Conjugated Estrogens
- Cyclophosphamide
- Cyclosporin A
- Diethylstilbestrol
- Dyes that Metabolize to Benzidine
- Direct Black 38
- Direct Blue 6
- Environmental Tobacco Smoke
- Erionite
- Ethylene Oxide
- Melphalan
- Methoxsalen with Ultraviolet A Therapy (PUVA)
- Mustard Gas
- 2-Naphthylamine
- Radon
- Silica, Crystalline (Respirable Size)
- Quartz
- Cristobalite
- Tridymite
- Smokeless Tobacco
- Solar Radiation and Exposure to Sunlamps or Sunbeds
- Soots
- Strong Inorganic Acid Mists Containing Sulfuric Acid
- Tamoxifen
- Tars and Mineral Oils
- Thiotepa
- Thorium Dioxide
- Tobacco Smoking
- Vinyl Chloride
How do carcinogens affect our genes?
Passed onto us from out parents is our genome, which contains all of our
hereditary factors. Each cell
in the human body (excluding sex cells) contains a complete set of all our
genes-a copy of the human genome. Our genes (segments of genetic material, or
DNA) contain the information that directs cells to make certain proteins. Each
gene
sequence is associated with a particular protein. Our body needs certain
proteins to grow and function properly. Accordingly, if gene
sequences are altered or damaged, certain important proteins will not be
sufficiently present in the body. Carcinogens affect our genes by altering and
damaging our genetic sequence, thus disabling accurate protein
synthesis. In other words, if a carcinogen has changed (or mutated) the DNA,
the altered genes will no longer function properly. The gene
may now code for a wrong protein
or for no protein
at all. So, as our body reads each gene
to create proteins, necessary proteins will be lacking. This will affect
proper functions, leaving our body with deficiencies that may lead to diseases
or cancer.
Cancer results from normal cells that loose control of normal replication
and proliferate (divide continuously and uncontrollably). This change in cell
behavior results from changes in the function and activity of genes.
Carcinogens alter gene
activity, which can harm our bodies and damage tissues. Carcinogens damage
genes that control cell
division rates or genetic stability; this can lead to abnormal growth control
mechanisms and causes uncontrolled cell
division, eventually leading to a cancerous tumor. Two types of genes that
control cell
division are oncogenes
and tumor suppressor genes. An oncogene is a gene
that when activated causes the transformation of normal cells into cancerous
tumor cells. A tumor suppressor gene
is one that inhibits replication
of cells (restraining tumor growth) having an opposite effect than an oncogene.
Carcinogens impact these genes by actually binding into the grooves of the
double helixes of the DNA molecule, altering function of these genes by
turning them "on" and "off". However, for cancer to come
about, it is necessary for both the oncogene to be turned "on" and
the tumor suppressor gene
to be turned "off". If the oncogene remains "off" or the
tumor suppressor gene
remains "on", than the cancer will not occur and the cell
will function normally. In more than 50% of all human cancers, mutations are
identified in a specific tumor suppressor gene, p53. When binding to the DNA
structure, carcinogens can also affect the "on" and "off"
sequences of other genes and can impact the cell's control over its replication
and protein
synthesis. All these types of alterations to genes can cause damage to cells
and tissues leading to tumors or disease.
The body is constantly replicating and reading DNA
in every cell. During these numerous replications an error can almost
certainly occur in the normal processes of replicating the DNA. Fortunately,
our cells have mechanisms that double check DNA as it is being replicated to
catch errors in the copy. This can correct a lot of mutations; however,
carcinogens increase the likelihood that errors will occur. Under certain
circumstances, the DNA
repair mechanism can repair the errors in DNA
caused naturally and by carcinogens. However, if not repaired, cells will
duplicate their DNA
during normal cell division and will duplicate damaged DNA
in the process, leading to gene
mutations (changes in the gene). Also, carcinogens may lead to errors by
affecting the enzymes (special proteins) that actually replicate DNA
during cell cycling. When the replication, or "spell check"
mechanisms are damaged, errors in our DNA
will not be caught. These gene
mutations can remain hidden within our genome
and then reveal themselves many years later in damaged tissues as tumors.
Chemicals and Other Harmful Elements In Our Environment
Reading the above list of carcinogens, one will notice that most of the
carcinogens are chemicals. However, the production of synthetic organic
chemicals continues to grow, even though we know that there are many health
problems created by these chemicals. In 1918, about 10 million pounds of
synthetic organic chemicals were produced, used, and disposed of in the United
States. By 1936, that number reached about 860 million pounds. Over the years
the numbers have continued to dramatically increase: 1941, 2 billion; 1944, 37
billion; 1947, 38 billion; 1961, 100 billion; and 1979, 300 billion pounds of
synthetic organic chemicals were made, used and disposed of in the US
These numbers add up to almost 1,700 pounds of chemicals for every person
in the United States. We know that chemicals can cause many human diseases, so
it is questionable why we continue to produce and use these harmful chemicals
in increasing amounts.
Tobacco:
The chemicals 
in tobacco are common in causing harm to humans. Tobacco is a plant (shown
above) grown for its leaves. Most people encounter the harmful chemicals found
in tobacco from smoking cigarettes or cigars. It is considered an addictive
substance because it contains the chemical nicotine. The addictive nicotine
and other numerous chemicals in the tobacco cause many people to smoke as a
habit, even though labels and other warnings inform them of the many harms
that tobacco smoking can cause to the body. Tobacco smoking is the major cause
of lung cancer and other lung diseases. These diseases can occur because
chemicals in the tobacco alter genes that control normal cell
functions. When the cell's functions are negatively altered, tissues in the
lungs are damaged and can become cancerous. Besides smokers, tobacco can also
affect people who do not smoke cigarettes or cigars through environmental
tobacco smoke (second-hand smoke), smokeless tobacco (chewing tobacco), and
sniffing tobacco. Most people are aware of this carcinogen; however, even with
this knowledge a habit is difficult to break. Still, about 25.7% of the adult
population in the United States smokes.
Alcoholic Beverage Consumption:
Another substance that many people consume is alcohol. People may not be aware
of the fact that alcohol can cause major bodily damage, can lead to diseases,
and only recently has been named a carcinogen. There is some evidence of
health benefits associated with moderate 
alcohol consumption. However, drinking alcoholic beverages habitually and in
large quantities can lead to major problems, including liver cancer and liver
damage. Alcoholics may be aware of the damage alcohol causes to their bodies;
but again like cigarettes, it is difficult to stop using a substance when a
person is addicted to it. Some studies have even shown alcohol consumption to
be related to breast cancer, but this is not definitive. Also, research has
found genes that may increase a person's chances of alcoholism. This is what
is known as susceptibility to alcohol dependence, and a person with these
genes is more likely than a person without these genes to become an alcoholic
if he or she starts drinking. In other words, a person who has a genetic
susceptibility to alcoholism is more likely to be dependent on alcohol because
of his genes. So with early identification of this risk, through genetic
testing, people can avoid this condition by abstaining from alcohol
consumption. Because of the complex interactions between the numerous genes
involved and the alcohol consumption, research is still being done to
understand exactly how the genes impact alcoholism.
Asbestos:
Another major cause of disease is the compound asbestos. Asbestos is a
fiber-like, fire resistant material that was commonly used in construction
before 1975 as an insulator and roofing material. It is a cheap, common
material that works very well in building structures. Once it was discovered
that asbestos was carcinogenic, its use was highly reduced. Asbestos exposure
mainly occurs in asbestos mining and milling industries, construction,
fireproofing, and other industries. However, many old homes and buildings
still contain asbestos in their walls and roofs. In the United States, 600,000
tons of asbestos is still used every year, even though this compound presents
a major health problem. Asbestos, however, does not pose harm until the tiny
fibrous particles become airborne. When it becomes airborne, asbestos can be
inhaled or ingested causing tissue damage. Asbestos has been found to cause
mesothelioma (an unusual tumor of the linings of the chest and abdominal
cavity), lung cancer, and increases in gastrointestinal cancer as well as
asbestosis (a chronic fibrous disease of the lung).
Pesticides:
Pesticides are chemical substances used on large crops in farms to protect
against molds, insects and fungi that are eating and destroying the crops.
These pesticides however, leave residues, are absorbed into the crops, and can
later be ingested by consumers. The farmers who are around the crops and are
spraying the chemicals can also inhale these pesticides. While pesticides are
very low on the list of hazardous risks to human health, research has found
that in high doses the numerous pesticides being used can cause health
problems ranging from mild toxic poisoning to cancers and other major health
disorders. However, pesticide residues are not a substantial risk factor for
cancer because the US Department of Agriculture regulates this to assure safe
food supplies. Of note, however, is the fact that recent studies indicate that
two pesticides, kepone and dibromochloropropane, cause sterility in men.
Therefore, even though we have federal regulation of pesticide levels in
consumer foods to help reduce human contact with these chemicals, research
still shows that these chemicals can cause major harm.
Arsenic:
Arsenic (chemical symbol above) is a naturally occurring element found in
rocks and soils. Arsenic can also be found in water supplies when minerals in
rocks and soils dissolve into ground water. Arsenic has been known to be a
toxic element for centuries. In modern years, it has 
been found that arsenic can also cause damage to normal gene
function contributing to skin, bladder, and other cancers. The risk of cancer
depends on the level and duration of exposure to the arsenic. Because of the
cancer risks associated with arsenic in water supplies, the US Environmental
Protection Agency (EPA) regulates the levels of arsenic found in our waters.
Arsenic in its natural form (and other compounds containing arsenic) is still
used in laboratories as chemical reagents. Some arsenic compounds (such as
arsenic trioxide) were also once used in medicine and dentistry. Again,
because of arsenic's carcinogenic properties, it is no longer used for
therapeutic purposes, but is still used as an insecticide and weed killer.
Arsenic has been found to be toxic to humans, can lead to cancerous growths,
is still a substance that is used as a pesticide, and can also be found in
drinking water; we must be aware of it and its health hazards.
Chemicals in drinking water:
Safe drinking water is a significant health concern. Water chlorination is a
standard treatment technique that has greatly decreased death from infectious
disease and was a major public health advance in the 20th century. However,
chemical contaminants may still be present in finished water. People are
becoming more aware of health risks linked to water contaminated by chemical
runoff. For example, hexavalent chromium compounds are carcinogenic compounds
found in water supplies, made famous by the movie Erin Brockovich. People
attempt to rid tap water of chemicals and contaminants by using home water
treatment units, although the effectiveness of using these products is
questionable. Such systems are usually considered a temporary solution and no
one system removes all possible contaminants. The only permanent solutions to
water contamination problems are discontinuation of the source of the
contamination or finding a new drinking water source. Governmental action is
being taken to control the chemical exposure to water sources. On March 28,
2000, Vice President Al Gore announced new proposed US EPA water standards to
help ensure the safety of tap water throughout the United States. Gore also
announced FY 2001 budget proposals that would allocate $825 million to the
Safe Drinking Water Revolving Loan Fund to offer low-interest loans to
communities in order to help them improve their water systems and meet EPA
regulations.
Lead:
Lead is a common, useful metal that is easy to work with and is cheap.
However, it was found that lead in the body is dangerous because it interferes
with normal body functions and can alter cellular function. Leaded paint and
leaded gasoline have been phased out; however, lead remains in old paint,
household dust, soil, pipe solder (from which it leaches into water) and some
ceramics. At high doses, lead has long been known to cause severe health
problems-muscle and abdominal pain, brain disease, paralysis and even death.
Infants, children, and pregnant women, because of their unborn child, are
threatened by even small amounts of lead in their environment because of
potential damage to proper development. In recent years, scientists are
discovering the effects of low-level lead exposures. Basic research has shown
the adverse effects on children's IQ and physical development of lead levels
previously considered safe. Accordingly, lead has been declared the number one
environmental hazard to American children. Further, the statistical
requirements for tolerable levels of lead in blood have been lowered by the
federal Centers for Disease Control and Prevention.
Radon:
Radon (chemical symbol above) is a heavy radioactive gaseous element that is
known to cause cancer. It is a natural element and is not a 
commercial product. A person cannot see, smell, or taste radon, but it is a
problem that is found in many homes because of the radioactive particles
emitted from it. Potential human exposure to radon is through inhalation and
ingestion. Radon can be found in the air and in working and living spaces
where radon enters through the ground, groundwater, or building materials.
Breathing air that has radon in it may lead to lung problems, most notably
lung cancer. Additionally, radon is the second leading cause of lung cancer in
the United States today. Radon is also used (following strict guidelines) in
many laboratories for chemical reactions and tests.
Mustard Gas and Agent Orange:
Mustard Gas and Agent Orange are names given to two groups of chemicals that
were tools of chemical warfare. Mustard Gas refers to several manufactured
chemicals that do not occur naturally in the environment. It is, in its pure
form, a colorless and odorless liquid. When mixed with other chemicals, it
looks brown and has a garlic-like smell. Mustard gas has been used in wars
including World Wars I and II. Mustard gas is not presently used in the United
States, except for research purposes, and all remaining supplies of lethal
military chemical agents, including mustard gas, were instructed to be
destroyed by 1997. Exposure to the general public is not a major threat, but
people affected by this chemical in wartime still live with its health
affects. Exposure to mustard gas causes skin to burn, respiratory damage and
can even cause lung cancer. Agent Orange was a government code name for a
chemical mixture used to defoliate trees and shrubberies (where enemies could
hide) in areas of tropical climates. It was tested during the Vietnam War and
was widely used during the height of the war (1967-68). Its use was diminished
and eventually discontinued in 1971. In 1993, a government study of Agent
Orange showed evidence linking it to different types of cancers and skin
diseases.
Possible Effects of Cell
Phones on Human Health:
In the midst of the growing use of cell
phones (or mobile phones) there has been much concern about possible health
hazards from their use. Mobile phones emit low levels of radio frequency
energy (i.e., radio frequency radiation) in the microwave range while being
used. They also emit very low levels of radio frequency energy (RF),
considered non-significant, when in the stand-by mode. It is well known that
high levels of RF can produce biological damage through heating effects (this
is how your microwave oven is able to cook food). However, it is not known
whether, to what extent, or through what mechanism, lower levels of RF might
cause adverse health effects. Although some research has been done to address
these questions, no clear picture of the biological effects of this type of
radiation has emerged to date. Consequently, available science does not allow
researchers to conclude that mobile phones are absolutely safe, or that they
are unsafe.
The existing scientific evidence is conflicting and research methods in many
of the studies performed have been flawed. Animal experiments investigating
the effects of the RF exposures characteristic of mobile phones have yielded
conflicting results. A few animal studies, however, have suggested that low
levels of RF can accelerate the development of cancer in laboratory animals.
Some people who have used mobile phones have been diagnosed with brain cancer,
but it is important to understand that this type of cancer also occurs among
people who have not used mobile phones. Research continues to be performed to
answer this key question: Is the risk of developing a particular form of
cancer greater among people who use mobile phones than among the rest of the
population?
Possible Effects of Electric and Magnetic Field Power-Lines on Human
Health:
In our increasing technological world, where people in industrial areas live
beneath miles of power-lines, the National Institute of Environmental Health
Sciences (NIEHS) researched health effects of electric and magnetic fields. In
their hazard evaluation they outlined the possible human health risks
associated with exposure to extremely low frequency electric and magnetic
fields (ELF-EMF). The NIEHS concluded that exposure to ELF-EMF cannot be
recognized as entirely safe because of weak scientific evidence that exposure
may pose a leukemia
hazard. The strongest evidence for health effects comes from associations
observed in human populations with two forms of cancer: childhood leukemia
and chronic lymphocytic leukemia
in occupationally exposed adults. Because studies failed to show consistent
patterns and virtually everyone in the United States uses electricity and
therefore is routinely exposed to ELF-EMF, no major regulatory actions were
reasonable. Instead it was decided to continue educating the public about
reducing exposures. No other cancers or non-cancer health outcomes provided
sufficient evidence of a risk to currently warrant concern.
Environment and Disease
Radiation:
Radiation is electromagnetic energy emitted in the form of rays or particles.
Radiation is everywhere and cannot be eliminated from our environment, but it
is possible to reduce our risks by controlling our exposure to it. As
mentioned above, radon is one source of radiation and 
also mobile phones emit a type of low-level radiation called radio frequency
radiation. Some other types of radiation include X rays, solar radiation
(ultraviolet rays) and gamma rays. These types of radiation can be found in
many forms, such as during exposure to the sun, sunlamps or sunbeds and during
cancer treatments. Radiation is used in medicine for diagnosing diseases (such
as when having an X ray taken) and treating diseases (such as radiation
therapy for cancer patients). Radiation can also be found near nuclear power
facilities and nuclear waste dumpsites. Radiation is similar to many hazardous
chemicals found in our environment because it is a carcinogen. Prolonged or
frequent exposure to radiation or radioactive particles can causes genetic
mutations in DNA
that may lead to cancers and other genetic defects. Current evidence suggests
that any exposure to radiation poses some risk. The government's Radiation
Protection Division is set up to help protect the public from radiation
exposure and clean up radioactively contaminated sites.
Breast Cancer:
Breast cancer kills more women than any other cancer except for lung cancer.
Breast cancer is a malignancy that is caused by interactions between genes and
several possible environmental factors-including chemical pollutants, diet,
and tobacco and alcohol use. Found to be linked to 5-10% of all cases of
breast cancer are two genes, BRCA1
and BRCA2. However, studies geared toward environmental factors have recently
focused on pesticides and other chemicals called environmental estrogens (or
conjugated estrogens) because they imitate some properties of the female sex
hormone estrogen. Experts believe estrogen can cause genetically altered
breast cells to divide more rapidly than normal cells, resulting in a tumor.
So, it is similarly believed that the environmental estrogens can do the same
damage. However, in some animal studies, breast cancer-causing chemicals do
not produce a significant increase in tumors unless estrogen is also present.
More research still needs to be done to find a direct and conclusive answer to
the interactions between genes and environment in breast cancer. Once these
interactions are better understood, doctors will be able to design more
effective strategies for the treatment and prevention of this disease.
Asthma:
Asthma is an inflammatory disease of the lung. Besides respiratory infections,
common triggers of asthma in our environment are cigarette smoke, cockroaches,
dust mites, mold, pets and animals, pollen, cold air, and stress. Children
with an asthmatic parent are much more likely to become asthmatic themselves,
so there is an important genetic role in the disease. Although the familial
predisposition to asthma may involve genetic factors, environmental factors
also pay a major role in asthmatics. Research shows that exposure to
environmental tobacco smoke appears to be associated with an increased risk of
wheezing in infants and recurrent wheezing in non-allergic children. As the
child develops, these respiratory problems may lead to asthma. Asthma both as
an illness and as a cause of death has increased in the United States and
other developed countries over the past 15 years despite major improvements in
outdoor air quality and major declines in other pulmonary diseases, such as
tuberculosis and pneumonia. By studying the environmental aspects of asthma,
researchers hope to find new treatments for this very prevalent disease.
Can our environment help reduce disease?
Herbal Medicines From Our Environment:
Herbal medicine, also called botanical medicine or phytomedicine, refers to
the use of any plant's seeds, berries, roots, leaves, bark, or flowers for
medicinal purposes. Some have questioned whether natural herbs from our
environment can and should be used as medicine. Medicinal herbs are actually
some of our oldest medicines, used since humans have suffered from illness,
and has been documented as far back as the eighteenth century. In recent years
herbs have again been increasingly publicly used as medicine, which is
evidence of a public interest in wanting alternatives to conventional
medicine. The Federal Drug Administration (FDA), however, indicates that herbs
can only be sold as dietary supplements. There are currently (as of September
2000) approximately 1500 botanicals sold as dietary supplements or ethnic
traditional medicines. However, since these botanicals are not technically
sold as "medicinal drugs", herbal formulations are not subject to
FDA pre-market toxicity testing to assure their safety or efficacy. Agencies,
including the FDA and National Toxicology Program (NTP), are continuing
further research to increase knowledge about herbal medicines and their
potential toxicities and benefits. This knowledge may soon reveal a whole new
branch of medicine and drug treatment.
Links For More Information On Environment and Health...
National Institute of Environmental Health Sciences (NIEHS)
www.niehs.nih.gov/
National Institutes of Health (NIH)
www.nih.gov/
US Environmental Protection Agency (EPA)
www.epa.gov
US Department of Health and Human Services
www.hhs.gov
Sources-- U.S. Department of Health and Human Service, National
Toxicology Program, National Institute of Environmental Health Sciences,
National Institutes of Health, Federal Drug Administration, U.S. Geological
Survey, www.newsweek.com, www2.potsdam.edu/alcohol-info/, www.yahoo.com,
www.adam.com, www.radon.com, www.broadcasthealth.com, www.ucop.edu,
www.lbl.gov, www.britannica.com