There are millions of chemicals on Earth — some found in nature, and others made by people. We use them every day in lots of different ways. But it’s important to know that chemicals can be harmful to both people and the planet if they aren’t handled correctly.

A chemical is a substance that has specific properties or characteristics we can use to identify it. They may interact with other substances and change form. Chemicals can get into our bodies through our skin, things we eat and drink, and the air we breathe — this is called exposure. How harmful chemicals are depends on how we’re exposed, the amount of the chemical we’re exposed to, and the length of time that we’re exposed. In addition, some people, such as children or those with health problems, can be more vulnerable to harmful chemicals.

Arsenic is an element that exists naturally in the Earth’s crust. Small amounts of arsenic are found in some rock, soil, water, and air. When arsenic combines with other chemical elements, it creates compounds, or chemical mixtures. When people come in contact with arsenic in the environment, it is often with compounds.

Arsenic spreads through the environment naturally through soil erosion (when soil is washed away by water) or storm water runoff (when water from rain or melted snow runs over the ground). Arsenic can be found in different forms — as pure arsenic, or combined with other elements to form compounds.

High levels of arsenic can also build up as a result of human activities, such as mining, farming, and other industries. This can be dangerous, because arsenic is poisonous to people and can cause serious health effects.

How is arsenic used?

Arsenic is sometimes used in:

• Pesticides (chemicals that kill pests)
• Products used in making glass
• Wood preservatives (products that help keep wood in good condition)

Arsenic may be used in the production of certain kinds of glass. It’s also added to heavy metals to make them stronger, creating compounds called alloys.

How can people be exposed to arsenic?

People can be exposed to (come in contact with) arsenic when it gets into food, water, and air. Here’s the good news: it’s very unlikely that you’ll be exposed to dangerous levels unless your job involves regular contact with arsenic (for example, if you work with certain metals or wood).

How can arsenic affect my health?

Symptoms of arsenic exposure can vary depending on:

• How arsenic gets into your body
• How much arsenic gets into to your body
• How long you’re exposed to arsenic

Breathing in high levels of arsenic can cause a sore throat and irritation of the lungs. Repeated exposure to arsenic over time can damage many organs, including the kidneys, stomach, and liver. It can also cause different kinds of cancer. Swallowing or breathing in a lot of arsenic may even cause death.

Exposure to low levels of arsenic can cause:

• Damage to the heart and blood
• Damage to the nervous system
• Nausea and vomiting (feeling sick and throwing up)
• Skin problems, such as warts, redness, and swelling

Arsenic may hurt an unborn baby if a woman is exposed while she’s pregnant.

Carbon monoxide is an odorless, colorless gas that comes from burning things like kerosene, coal, or wood. It is a poison.

Breathing air containing only a very small amount of carbon monoxide can cause carbon monoxide poisoning. Carbon monoxide replaces oxygen in the blood.

What happens if a person breathes carbon monoxide?

• symptoms like the flu or a cold
• blurred vision
• stomach aches
• trouble breathing
• sleepiness
• ringing in the ears

Carbon monoxide can come from

• broken gas water heaters and furnaces
• space heaters that don’t have vents
• gas clothes dryers
• tobacco smoke
• fuels burned in wood and gas stoves

Carbon monoxide detectors help prevent carbon monoxide poisoning in the home.

Lead is a soft, bluish-white metal that exists naturally in the environment. When lead combines with other chemical elements, it creates compounds, or chemical mixtures. When people come in contact with lead in the environment, it is often with compounds.

In the past, lead was used often in products such as house paint, pesticides (chemicals that kill pests), and gasoline. In the 1970s, science clearly showed that lead is highly toxic to people — especially children. The government passed laws that limit the use of lead, but it still lingers in the environment.

Where is lead found?

Most homes built before 1960s, as well as some built in the 1970s, have lead paint in them. Peeling paint chips and dust in these homes may contain lead. Additionally, some older homes may have plumbing pipes with lead in them. If these pipes are still in use, lead can get into the water.

Lead can also be found in:

• Ceramic glazes (glazes for pottery)
• Fishing sinkers (used to help fishing hooks go underwater)
• Leaded crystal glassware
• Some toys and jewelry

How are people exposed to lead?

Lead can get into your body if you breathe in dust from lead paint, or if you drink water with lead in it from old plumbing pipes. Children and babies may also come in contact with lead by:

• Eating paint chips or soil that contains lead
• Playing with toys that have lead in them
• Sucking on their fingers after playing in the dirt or dust

The good news about lead poisoning is that it’s 100% preventable. That means we can keep it from happening by preventing exposure to lead in the first place.

How can lead affect my health?

Lead harms many systems in the body — especially the central nervous system (the system that includes the brain and spinal cord). It’s most dangerous for children because their nervous systems are still developing. Repeated exposure to low levels of lead can affect children’s growth, and cause learning or behavior problems.

If a child swallows a lot of lead, it can seriously damage the brain, and may even cause death. Lead poisoning can also cause:

• Anemia (when your blood doesn’t carry enough oxygen to the rest of your body)
• Colic (crying in a baby that lasts longer than 3 hours a day and isn’t caused by a medical problem)
• Damage to the kidneys
• Muscle weakness

Lead may also hurt an unborn baby if a woman is exposed while she’s pregnant.

Symptoms of Lead Poisoning

• abdominal pain, nausea or vomiting
• behavioral problems or irritability
• constipation
• difficulty concentrating
• excessive tiredness or lethargy
• headaches
• loss of appetite
• metallic taste in the mouth
• muscle and joint weakness or pain

These symptoms may or may not be present, and of course each of them can also be caused by many other common illnesses. But in cases where some of these symptoms are present for a long time, no other cause has been found, and there may have been some exposure to lead, then tests for test poisoning should be considered.

Mercury — sometimes called quicksilver — is a natural metal. It’s a shiny, silver liquid that can evaporate into an invisible gas. Since you can’t see it, it’s easy to breathe it in without knowing it. When mercury combines with other chemical elements, it creates compounds, or chemical mixtures. When people come in contact with mercury in the environment, it is often with compounds. It’s very important to dispose of (get rid of) mercury and mercury compounds properly, or they can wind up contaminating (polluting) soil, water, and air.

What products might have mercury in them?

People have used mercury throughout history — for everything from making hats to making medicine. Now that experts know it can be dangerous, it’s used less often. But it’s still possible to find mercury in a variety of products, including:

• Batteries
• Compact fluorescent light bulbs (CFL)
• Dental fillings
• Glass thermometers
• Paint

Mercury can also be used in some industrial processes.

How can people be exposed to mercury?

Mercury is toxic to people — especially children. In the United States, the most common way to be exposed (come in contact with) to mercury is by eating fish or shellfish that have high levels of mercury.

You can also get sick from:

• Breathing it in
• Drinking contaminated water
• Touching it

How can mercury affect my health?

Exposure to mercury can cause mercury poisoning, which can damage many body systems, particularly the brain and kidneys. Brain damage from mercury poisoning can cause a variety of symptoms, including:

• Changes in vision or hearing
• Feeling irritated
• Loss of appetite (not feeling hungry)
• Memory loss
• Psychosis (losing touch with reality)
• Tremors (trembling)

In serious cases, mercury poisoning can even cause death. It may also hurt an unborn baby if a woman is exposed while she’s pregnant.

Symptoms of mercury exposure can vary depending on:

• How mercury gets into your body
• How much mercury gets into to your body
• How long you’re exposed to mercury

A single atom can make a big difference in the way a molecule works — so can its location. The everyday air we breathe has two atoms of oxygen (O2) in it. Ozone is a gas made up of three atoms of oxygen (O3). And while we need oxygen to survive, ozone can either help us or hurt us — depending on where it is.

What’s the difference between helpful and harmful ozone?

Ozone can be helpful or harmful to your health and the environment, depending on its location in the atmosphere. Helpful ozone exists naturally high above the Earth’s surface and protects us from the sun’s ultraviolet rays (radiation). Human-made air pollutants damage the helpful ozone.

Harmful ozone is close to the ground. It comes from human activities that release chemicals into the air, which react with sunlight to create ground-level ozone.

How can ozone affect my health?

When human-made air pollutants destroy helpful ozone, people may receive too much ultraviolet radiation. This may cause:

• Cataracts (clouding of eye lens, which leads to poor vision)
• Problem with immune system (the system that fights diseases)
• Skin cancer

Too much ultraviolet radiation may also damage crops (plants we grow for food) and other plants.

Contact with harmful ozone can cause:

• Coughing
• Irritated throat
• Worsening in respiratory (breathing) disorders, such as asthma and bronchitis

Regular contact with ozone can also cause permanent damage to the lungs, especially in children, because their lungs are still developing.

Radon is an invisible and odorless gas. It comes from the soil, rock and water under homes and other buildings. It moves up through the ground to the air above and into a home through cracks and other holes in buildings. Radon can be found all over the U.S.

Radon gas decays into radioactive particles that can get trapped in the lungs. This can damage the lungs. Breathing radon gas for a long time can cause lung cancer.

Most homes don't have a radon problem, but there is a simple test to find out if there is a high radon levels in a home. The good thing is that homes with high levels of radon can easily be fixed.

All homes with basements should be tested for radon.

Volatile organic compounds (VOCs) are chemicals that evaporate from a solid or liquid form at room temperature. Some VOCs exist naturally in the environment. Others are manufactured (made by people) and put into things that we use every day.

When VOCs evaporate into the air, they become invisible, so you can’t see them. Many VOCs also have no odor (smell). That makes it easy to breathe them in without knowing it.

The word “volatile” means unstable and possibly dangerous. That word gives you a clue about what VOCs are like — and why we need to be careful with them.

What products might have VOCs in them?

Many things that we use at home, school, and work contain VOCs. These include:

• Air fresheners
• Cleaning supplies
• Fuels
• Glue
• Hair spray
• Markers
• Paint

How can people be exposed to VOCs?

When someone uses a product with VOCs, the VOCs evaporate and stay in the air. This usually happens inside a room or building, because there’s less ventilation (air flow) than outside.

In other words, VOCs can affect indoor air quality. When we say “indoor air quality,” we’re usually talking about how the air you breathe when you’re inside might affect your health. And since most of us spend a lot of time indoors, the quality of that air matters.

You can also get sick by swallowing or touching VOCs. That’s why things such as cleaning supplies have warning labels — and why it’s important to read product warnings.

How can VOCs affect my health?

VOCs can make you sick. Someone who’s been poisoned by a VOC could develop:

• Damage to the central nervous system (the system that includes the brain and spinal chord)
• Eye, nose, or throat problems
• Headaches
• Liver or kidney damage

Some VOCs can also cause cancer if people are exposed to them for a long period of time.