Arsenic [CDC]

How People Are Exposed to Arsenic:
People are most likely exposed to inorganic arsenic through drinking water. This is especially true in areas with water sources that naturally have higher levels of inorganic arsenic. People can also be exposed to inorganic arsenic by eating such foods as rice and some fruit juices. Other sources of inorganic arsenic exposure include contact with contaminated soil or dust, or with wood preserved with arsenic compounds.

Exposure to organic arsenic compounds happens when people eat seafood. These forms of arsenic are considered to be non-toxic or considerably less toxic than inorganic arsenic.

How Arsenic Affects People’s Health:
Unusually large doses of inorganic arsenic can cause symptoms ranging from nausea, vomiting, and diarrhea to dehydration and shock. Long-term exposure to high levels of inorganic arsenic in drinking water is associated with certain medical conditions. These conditions include skin disorders, an increased risk for diabetes, high blood pressure, and several types of cancer. Inorganic arsenic and arsenic compounds are considered to be cancer-causing chemicals.

Studies have not found organic arsenic in seafood to be toxic to humans.

Asbestos [ EPA ]
How Can People Be Exposed to Asbestos:
Asbestos fibers may be released into the air by the disturbance of asbestos-containing material during product use, demolition work, building or home maintenance, repair, and remodeling. In general, exposure may occur only when the asbestos-containing material is disturbed or damaged in some way to release particles and fibers into the air.

Health Effects From Exposure to Asbestos:
Exposure to asbestos increases your risk of developing lung disease. That risk is made worse by smoking. In general, the greater the exposure to asbestos, the greater the chance of developing harmful health effects.

Disease symptoms may take many years to develop following exposure.

Asbestos-related conditions can be difficult to identify. Healthcare providers usually identify the possibility of asbestos exposure and related health conditions like lung disease by taking a thorough medical history. This includes looking at the person’s medical, work, cultural and environmental history.

After a doctor suspects an asbestos-related health condition, he or she can use a number of tools to help make the actual diagnosis. Some of these tools are physical examination, chest x-ray and pulmonary function tests. Your doctor may also refer you to a specialist who treats diseases caused by asbestos.

• lung cancer
• mesothelioma, a rare form of cancer that is found in the thin lining of the lung, chest and the abdomen and heart
• asbestosis, a serious progressive, long-term, non-cancer disease of the lungs

For more information on these and other health effects of asbestos exposure see the Agency for Toxic Substances and Disease Registry, the National Institute for Occupational Safety and Health and the National Cancer Institute.

Lead [ EPA ]
How People Are Exposed to Lead:
Adults may be exposed to lead by eating and drinking food or water containing lead or from dishes or glasses that contain lead. They may also breath lead dust by spending time in areas where lead-based paint is deteriorating, and during renovation or repair work that disturbs painted surfaces in older homes and buildings. Working in a job or engaging in hobbies where lead is used, such as making stained glass, can increase exposure as can certain folk remedies containing lead. A pregnant woman’s exposure to lead from these sources is of particular concern because it can result in exposure to her developing baby.

How Lead Affects People’s Health:

Lead can affect almost every organ and system in your body. Children six years old and younger are most susceptible to the effects of lead.

Children
Even low levels of lead in the blood of children can result in:

• Behavior and learning problems
• Lower IQ and Hyperactivity
• Slowed growth
• Hearing Problems
• Anemia

In rare cases, ingestion of lead can cause seizures, coma and even death.

Pregnant Women
Lead can accumulate in our bodies over time, where it is stored in bones along with calcium. During pregnancy, lead is released from the mother's bones along with calcium and can pass from the mother exposing the fetus or the breastfeeding infant to lead. This can result in serious effects to the developing fetus and infant, including:

• Cause the baby to be born too early or too small;
• Hurt the baby’s brain, kidney’s, and nervous system;
• Increase the likelihood of learning or behavioral problems; and
• Put the mother at risk for miscarriage.

Find out more about lead's effects on pregnancy and lactating women:

• Effects of Workplace Hazards on Female Reproductive Health, National Institute for Occupational Safety and Health. 
• Guidelines for the Identification and Management of Lead Exposure in Pregnant and lactating Women, National Center for Environmental Health. 

Other Adults
Lead is also harmful to other adults. Adults exposed to lead can suffer from:

• Cardiovascular effects, increased blood pressure and incidence of hypertension;
• Decreased kidney function; and
• Reproductive problems (in both men and women).

Read more on the health effects of lead

• EPA’s Integrated Science Assessment for Lead
• Agency for Toxic Substances and Disease Registry (ATSDR). 

Petroleum and Hydrocarbons [ EPA ]
Total petroleum hydrocarbons (TPH) is a term used to describe a large family of several hundred chemical compounds that originally come from crude oil. Crude oil is used to make petroleum products, which can contaminate the environment. Because there are so many different chemicals in crude oil and in other petroleum products, it is not practical to measure each one separately. However, it is useful to measure the total amount of TPH at a site.

How People Are Exposed to Petroleum Hydrocarbon:

• Everyone is exposed to TPH from many sources.
• Breathing air at gasoline stations, using chemicals at home or work, or using certain pesticides.
• Drinking water contaminated with TPH.
• Working in occupations that use petroleum products.
• Living in an area near a spill or leak of petroleum products.
• Touching soil contaminated with TPH.

How Petroleum Hydrocarbon Affects People’s Health:
Some of the TPH compounds can affect your central nervous system. One compound can cause headaches and dizziness at high levels in the air. Another compound can cause a nerve disorder called "peripheral neuropathy," consisting of numbness in the feet and legs. Other TPH compounds can cause effects on the blood, immune system, lungs, skin, and eyes.

Animal studies have shown effects on the lungs, central nervous system, liver, and kidney from exposure to TPH compounds. Some TPH compounds have also been shown to affect reproduction and the developing fetus in animals.

Per- and polyfluoroalkyl substances (PFAS) [ EPA ]

How Can People Be Exposed to PFAS:
There are a variety of ways that people can be exposed to these chemicals and at different levels of exposure. For example, people can be exposed to low levels of PFAS through food, which can become contaminated through:

• Contaminated soil and water used to grow the food,
• Food packaging containing PFAS, and
• Equipment that used PFAS during food processing.

People can also be exposed to PFAS chemicals if they are released during normal use, biodegradation, or disposal of consumer products that contain PFAS. People may be exposed to PFAS used in commercially-treated products to make them stain- and water-repellent or nonstick. These goods include carpets, leather and apparel, textiles, paper and packaging materials, and non-stick cookware.

People who work at PFAS production facilities, or facilities that manufacture goods made with PFAS, may be exposed in certain occupational settings or through contaminated air.

Drinking water can be a source of exposure in communities where these chemicals have contaminated water supplies. Such contamination is typically localized and associated with a specific facility, for example,

• an industrial facility where PFAS were produced or used to manufacture other products, or
• an oil refinery, airfield or other location at which PFAS were used for firefighting.

PFOA, PFOS, and GenX have been found in a number of drinking water systems due to localized contamination. You can view more information about exposures to PFAS through drinking water on Drinking Water Health Advisories for PFOA and PFOS.

Health Effects From Exposure to PFAS:
There is evidence that exposure to PFAS can lead to adverse health outcomes in humans. If humans, or animals, ingest PFAS (by eating or drinking food or water than contain PFAS), the PFAS are absorbed, and can accumulate in the body. PFAS stay in the human body for long periods of time. As a result, as people are exposed to PFAS from different sources over time, the level of PFAS in their bodies may increase to the point where they suffer from adverse health effects.

Studies indicate that PFOA and PFOS can cause reproductive and developmental, liver and kidney, and immunological effects in laboratory animals. Both chemicals have caused tumors in animal studies. The most consistent findings from human epidemiology studies are increased cholesterol levels among exposed populations, with more limited findings related to: infant birth weights, effects on the immune system, cancer (for PFOA), and thyroid hormone disruption (for PFOS).

Oral exposure studies of PFBS in animals have shown effects on thyroid hormone disruption, reproductive organs and tissues, developing fetus, and kidney. Based on dose-response information across different sexes, lifestages, and durations of exposure, the thyroid appears to be particularly sensitive to oral PFBS exposure. The data are inadequate to evaluate cancer effects associated with PFBS exposure.

• Learn more about the Human Health Toxicity Assessment for PFBS

Polycyclic Aromatic Hydrocarbons (PAHs) [CDC]

How People Are Exposed to PAHs:
People are usually exposed to mixtures of PAHs. Breathing air contaminated with motor vehicle exhaust, cigarette smoke, wood smoke, or fumes from asphalt roads are common ways exposure occurs. People take in PAHs when they eat grilled or charred meats or foods or foods on which PAH particles have settled from the air. After PAHs are swallowed, breathed in, or in some cases, passed through the skin, the body converts PAHs into breakdown products called metabolites that pass out of the body in the urine and feces.

How PAHs Affect People’s Health:
Human health effects from environmental exposure to low levels of PAHs are unknown. Large amounts of naphthalene in air can irritate eyes and breathing passages. Workers who have been exposed to large amounts of naphthalene from skin contact with the liquid form and from breathing naphthalene vapor have developed blood and liver abnormalities. Several of the PAHs and some specific mixtures of PAHs are considered to be cancer-causing chemicals.

Polychlorinated Biphenyls (PCBs)[ EPA ]

How People Are Exposed to PCBs:
Today, PCBs can still be released into the environment from:

• Poorly maintained hazardous waste sites that contain PCBs
• Illegal or improper dumping of PCB wastes
• Leaks or releases from electrical transformers containing PCBs
• Disposal of PCB-containing consumer products into municipal or other landfills not designed to handle hazardous waste
• Burning some wastes in municipal and industrial incinerators

PCBs do not readily break down once in the environment. They can remain for long periods cycling between air, water and soil. PCBs can be carried long distances and have been found in snow and sea water in areas far from where they were released into the environment. As a consequence, they are found all over the world. In general, the lighter the form of PCB, the further it can be transported from the source of contamination.

PCBs can accumulate in the leaves and above-ground parts of plants and food crops. They are also taken up into the bodies of small organisms and fish. As a result, people who ingest fish may be exposed to PCBs that have bioaccumulated in the fish they are ingesting.

The National Center for Health Statistics, a division of the Centers for Disease Control and Prevention, conducts the National Health and Nutrition Examination Surveys (NHANES). NHANES is a series of U.S. national surveys on the health and nutrition status of the noninstitutionalized civilian population, which includes data collection on selected chemicals. Interviews and physical examinations are conducted with approximately 10,000 people in each two-year survey cycle. PCBs are one of the chemicals where data are available from the NHANES surveys.

How PCBs Affects People’s Health:
PCBs have been demonstrated to cause a variety of adverse health effects. They have been shown to cause cancer in animals as well as a number of serious non-cancer health effects in animals, including: effects on the immune system, reproductive system, nervous system, endocrine system and other health effects. Studies in humans support evidence for potential carcinogenic and non-carcinogenic effects of PCBs. The different health effects of PCBs may be interrelated. Alterations in one system may have significant implications for the other systems of the body. The potential health effects of PCB exposure are discussed in greater detail below.

• Cancer
• Non-Cancer Effects
• Immune Effects
• Reproductive Effects
• Neurological Effects
• Endocrine Effects
• Other Non-cancer Effects
• Integrated Risk Information System (IRIS)

Cadmium [ EPA IRIS ]

How Can People Be Exposed to Cadmium:

Exposure to cadmium occurs mostly in workplaces where cadmium products are made. The major routes of occupational exposure are inhalation of dust and fumes and incidental ingestion of dust from contaminated hands, cigarettes, or food.

The general population is exposed to cadmium by breathing tobacco smoke or eating cadmium-contaminated foods, which is the major source of cadmium exposure for nonsmokers. The expanding nickel–cadmium (NiCd) battery recycling industry is also a potential source for exposure.

Health Effects From Exposure to Cadmium:

Occupational exposure to cadmium can lead to a variety of adverse health effects including cancer. Acute inhalation exposure (high levels over a short period of time) to cadmium can result in flu-like symptoms (chills, fever, and muscle pain) and can damage the lungs. Chronic exposure (low level over an extended period of time) can result in kidney, bone and lung disease.

Chromium [ ATSDR ]

How Can People Be Exposed to Chromium:

Health Effects From Exposure to Chromium:

Dioxin [ EPA ]

How Can People Be Exposed to Dioxin:

Dioxins are mainly by-products of industrial processes but can also result from natural processes, such as volcanic eruptions and forest fires. Dioxins are unwanted by-products of a wide range of manufacturing processes including smelting, chlorine bleaching of paper pulp and the manufacturing of some herbicides and pesticides. In terms of dioxin release into the environment, uncontrolled waste incinerators (solid waste and hospital waste) are often the worst culprits, due to incomplete burning. Technology is available that allows for controlled waste incineration with low dioxin emissions.

Health Effects From Exposure to Dioxin:

Short-term exposure of humans to high levels of dioxins may result in skin lesions, such as chloracne and patchy darkening of the skin, and altered liver function. Long-term exposure is linked to impairment of the immune system, the developing nervous system, the endocrine system and reproductive functions.

Due to the omnipresence of dioxins, all people have background exposure and a certain level of dioxins in the body, leading to the so-called body burden. Current normal background exposure is not expected to affect human health on average. However, due to the high toxic potential of this class of compounds, efforts need to be undertaken to reduce current background exposure.

Mercury [ EPA ]

How Can People Be Exposed to Mercury:

Mercury exists in various forms, and people are exposed to each in different ways. The most common way people in the U.S. are exposed to mercury is by eating fish containing methylmercury. Other exposures may result from using or breaking products containing mercury. Common exposures: When most exposures to metallic mercury occur, they occur because mercury is released from a container, or from a product or device that breaks.  If the mercury is not immediately contained or cleaned up, it can evaporate, becoming an invisible, odorless, toxic vapor. Exposures may occur when people breathe this vapor and inhale it into their lungs. Poorly ventilated, warm, indoor spaces are of particular concern in cases of airborne mercury vapors. Note that where metallic mercury generally is contained in glass or metal, it does not pose a risk unless the product is damaged or broken and mercury vapors are released.  

Other compounds of mercury, like phenylmercury acetate and ethylmercury, have been commonly used as fungicides, preservatives, antiseptics (e.g., Mercurochrome, a trade name of the antiseptic merbromin) or disinfectants. They have also been used in a variety of products. Most uses have been discontinued.

Health Effects From Exposure to Mercury:

• The form of mercury (for example, methylmercury or elemental (metallic) mercury);
• The amount of mercury in the exposure;
• The age of the person exposed (unborn infants are the most vulnerable);
• How long the exposure lasts;
• How the person is exposed -- breathing, eating, skin contact, etc.; and
• The health of the person exposed.