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Your Environment. Your Health.

Environmental Agents

Smoke Stack

Environmental Agents | The NIEHS provides information about chemicals or factors in the environment to which humans are exposed that may cause adverse health effects

  • Acrylamide

    Acrylamide is a chemical widely used during the manufacturing of paper, dye, and other industrial products. It can also be formed when certain foods are cooked at high temperatures.

  • Air Pollution

    Air pollution is a mixture of natural and man-made substances in the air we breathe. It is typically separated into two categories: outdoor air pollution and indoor air pollution.

  • Allergens & Irritants

    Information on allergens, asthma, and pulmonary research performed at NIEHS | Additional resources for managing allergies

  • Aloe Vera

    Aloe is a succulent plant widely used in alternative medicine. There are at least 420 different plant species of Aloe. Aloe vera specifically refers to the Aloe barbadensis Miller plant, which is the most common form used in Aloe-based products.

  • Arsenic

    Arsenic is a naturally occurring element that is widely distributed in the Earth’s crust. It is found in water, air, food, and soil.

  • Bisphenol A (BPA)

    An introduction to BPA and health | Bisphenol A (BPA) is a chemical produced in large quantities for use primarily in the production of polycarbonate plastics and epoxy resins

  • Cell Phone Radio Frequency Radiation

    The National Toxicology Program (NTP) headquartered at NIEHS is leading the largest laboratory rodent study to date on cell phone radio frequency. NTP studies will help clarify any potential health hazards from exposure to cell phone radiation.

  • Climate Change

    Climate change is the result of the buildup of greenhouse gases in the atmosphere, primarily from the burning of fossil fuels for energy and other human activities. These gases, such as carbon dioxide and methane, warm and alter the global climate, which causes environmental changes to occur that can harm people's health and well-being.

  • Cosmetics and Personal Care Products

    Cosmetics and personal care products contain a mix of chemicals. Researchers are working to better understand if any of these affect human health. Some of the chemicals have already been classified as endocrine disrupting, which means they may interfere with the body’s hormones and cause adverse health effects.

  • Dioxins

    Dioxins are mainly byproducts of industrial practices. They are produced through a variety of incineration processes, including improper municipal waste incineration and burning of trash, and can be released into the air during natural processes, such as forest fires and volcanoes. Almost every living creature has been exposed to dioxins or dioxin-like compounds (DLCs).

  • Dust Mites and Cockroaches

    Dust mites are microscopic, insect-like pests that commonly live in house dust. They feed on flakes of dead skin, or dander, that are shed by people and pets. Cockroaches are another source of indoor allergens. Researchers have found a link between the presence of cockroaches and an increase in the severity of asthma symptoms.

  • Electric & Magnetic Fields

    Electric and magnetic fields (EMFs) are invisible areas of energy, often referred to as radiation, that are associated with the use of electrical power and various forms of natural and man-made lighting. Learn the difference between Ionizing and Non-Ionizing radiation, the Electromagnetic Spectrum, and how harmful EMFs are to your health

  • Endocrine Disruptors

    Endocrine disruptors are chemicals that may interfere with the body’s endocrine system and produce adverse developmental, reproductive, neurological, and immune effects in both humans and wildlife.

  • Essential Oils

    Essential oils are concentrated plant extracts that retain the natural smell and flavor of their source.

  • Flame Retardants

    Flame retardants are chemicals that are added or applied to materials in order to slow or prevent the start/growth of fire. They have been used in many consumer and industrial products since the 1970s, to decrease the ability of materials to ignite.

  • Formaldehyde

    Formaldehyde is a colorless, flammable, strong-smelling chemical widely used to make home building products. Most formaldehyde produced in the United States is for the manufacture of resins, such as urea-formaldehyde, used to make the adhesives for pressed wood products, such as particleboard, furniture, paneling, cabinets, and other products.

  • Ginkgo

    Ginkgo or Ginkgo biloba is one of the world’s oldest living tree species. Ginkgo has been used for many years for a variety of medicinal purposes.

  • Hair Dye

    Millions of women and men around the world enhance or change their appearance with hair dye. Hair dye is classified into three major groups — temporary, semipermanent, and permanent.

  • Harmful Algal Blooms

    A harmful algal bloom (HAB) occurs when toxin-producing algae grow excessively in a body of water. Algae are microscopic organisms that live in aquatic environments and use photosynthesis to produce energy from sunlight, just like plants.

  • Hazardous Material/Waste

    Hazardous wastes are discarded materials with properties that make them potentially harmful to human health or the environment.

  • Hexavalent Chromium

    Hexavalent chromium is a form of the metallic element chromium. Chromium is a naturally occurring element found in rocks, animals, plants, soil, and volcanic dust and gases. It comes in several different forms, including trivalent chromium and hexavalent chromium.

  • Hydraulic Fracturing & Health

    Hydraulic fracturing, or fracking, is a method used to extract natural gas and oil from deep rock formations known as shale. Using this method, drilling operators force water, sand, and a mix of chemicals into horizontally drilled wells, causing the shale to crack and release natural gas or oil.

  • Lead

    Lead is a naturally occurring metal found deep within the ground. It occurs in small amounts in ore, along with other elements such as silver, zinc or copper. Even though it's found in small amounts, there is an abundant supply of lead throughout the earth. | Learn about lead and the research NIEHS is conducting on lead exposure

  • Mercury

    Mercury, also known as quicksilver, is a naturally-occurring metal that is toxic to living organisms. Metallic or elemental mercury — an odorless, shiny, silver-white liquid — is commonly used in thermometers, barometers and fluorescent light bulbs. Metallic mercury is extremely dangerous with a few drops generating enough fumes to contaminate the air in a room. Furthermore, skin contact with the metal results in the absorption of mercury into the blood stream and potential health problems.

  • Mold

    Molds are microscopic organisms that play an important role in the breakdown of plant and animal matter. When molds are disturbed, they release tiny cells called spores into the surrounding air.

  • Nanomaterials

    Nano-sized particles exist in nature and can be created from a variety of products, such as carbon or minerals like silver, but nanomaterials by definition must have at least one dimension that is less than approximately 100 nanometers.

  • Ozone

    Ozone is a highly reactive form of oxygen. In the upper atmosphere, ozone forms a protective layer that shields us from the sun’s ultraviolet rays. At ground level, ozone is a harmful air pollutant and a primary constituent of urban smog.

  • Perfluoroalkyl and Polyfluoroalkyl Substances (PFAS)

    PFAS are a large, complex, and ever-expanding group of manufactured chemicals that are widely used to make various types of everyday products. For example, they keep food from sticking to cookware, make clothes and carpets resistant to stains, and create firefighting foam that is more effective. PFAS are used in industries such as aerospace, automotive, construction, electronics, and military.

  • Pesticides

    A pesticide is any substance used to kill, repel, or control certain forms of plant or animal life that are considered to be pests. Pesticides include herbicides for destroying weeds and other unwanted vegetation, insecticides for controlling a wide variety of insects, fungicides used to prevent the growth of molds and mildew, disinfectants for preventing the spread of bacteria, and compounds used to control mice and rats.

  • Pet Allergens

    Millions of Americans live with pets despite being allergic to them. Any furry animal may trigger allergy symptoms like sneezing or red, itchy eyes, but most commonly cats and dogs. Pet allergies can also make asthma harder to control.

  • Pollen

    To a tree or a flowering plant, pollen is necessary for life. But to millions of Americans, it is a source of seasonal misery. Pollen, a fine to coarse powdery substance, is created by certain plants as part of their reproduction process. It can appear from trees in the spring, grasses in the summer, and weeds in the fall.

  • Radon

    Radon is a colorless, odorless radioactive gas. It comes from the natural decay of uranium or thorium found in nearly all soils. It typically moves up through the ground and into the home through cracks in floors, walls and foundations. It can also be released from building materials or from well water.

  • Smoking and Vaping

    The link between cigarette smoke and disease, particularly lung cancer and cardiovascular disease, is well known. Cigarette smoking is the leading cause of preventable death in the United States.

  • Soy Infant Formula

    Soy formula is an infant food made using soy protein and other components. It is fed to infants as a supplement or replacement for human milk or cow milk formula | Learn about soy infant formula, how it affects infants, and how safe an NTP expert panel deemed soy formula

  • Styrene

    Styrene is a colorless, flammable liquid, which has a sweet odor and is highly volatile. Styrene is widely used to make plastics and rubber, which are used to manufacture a variety of products, such as insulation, pipes, automobile parts, printing cartridges, food containers, and carpet backing.

  • Water Pollution

    Water pollution is any contamination of water with chemicals or other foreign substances that are detrimental to human, plant, or animal health. Worldwide, nearly 2 billion people drink contaminated water that could be harmful to their health.

  • Weather Extremes

    Extreme weather can have adverse effects on human health, including dangers from flooding, heat, and severe cold. These events can have secondary concerns, ranging from wildfires to harmful algal blooms. NIEHS has resources on many of these areas.

Additional Topics


Chemicals (General)

  • CERCLA (The Comprehensive Environmental Response, Compensation, and Liability Act) Priority List of Hazardous Substances - The government’s list, in order of priority, of substances most commonly found at waste facility sites on the National Priorities List (NPL) that are determined to pose the most significant potential threat to human health due to their known or suspected toxicity and potential for human exposure.
  • Diseases and the Environment
  • Household Products Database - A database of more than 6,000 household products identifying key chemical ingredients and any acute or chronic health effects.
  • The Health Consequences of Involuntary Exposure to Tobacco Smoke - Toxmap uses interactive mapping software to help users explore the geographic distribution of TRI chemical releases, their amounts, and trends over time. TOXMAP helps users create nationwide or local area maps showing where TRI chemicals are released on-site into the air, water, and ground. Maps also show locations of Superfund sites on the National Priority List (NPL), listing all chemical contaminants present at these sites. Users can search the system by chemical name, chemical name fragment, and/or location (such as city, state, or zip code).
  • ToxMystery - The National Library of Medicine's interactive learning site is designed to help children age 7 to 10 find clues about toxic substances that can lurk in the home. ToxMystery provides a fun, game-like experience, while teaching important lessons about potential environmental health hazards. Teacher plans and classroom activities are included. ToxMystery is available in Spanish, including all lesson plans.
  • Tox Town - An interactive guide to toxic chemicals and environmental health risks you might encounter in everyday life, in everyday places.


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