Environmental Toxicology

Environmental Pollutants Control Program

The Environmental Pollutants Control Program, previously known as the Environmental Toxins Control Program, was created in November 2006 for Harris County Pollution Control (PCS) to provide Environmental Toxicology services. These services include but are not limited to, assessments of health effects from exposure to hazardous substances or conditions in various matrices (e.g., air, water, soil), act as an environmental advisory to communities potentially impacted by an exposure and educate citizens on environmental impacts so they may take proper action to protect themselves.

What is Environmental Toxicology?

A field of science that studies the harmful effects of chemicals and biological compounds on human health and the environment. Compounds released into the environment that produce negative health effects are known as pollutants. Pollutants fall under two classifications: toxicants and toxins. Both cause biochemical harm in different ways.


Toxic chemicals that are natural or artificial products introduced into the environment through human activities (anthropogenic) or natural events. Examples are industrial products, pesticides, carcinogens (e.g., asbestos), and volatile organic compounds (VOCs). At PCS, we mainly handle environmental pollutants that are toxicants.


Poisons produced from living cells or organisms, such as plants, animals, and bacteria. Examples are poisonous mushrooms or venom transferred from a snake’s bite. Toxins can damage different bodily functions (e.g., hemotoxins in snakes can destroy red blood cells and neurotoxins produced in bacteria can destroy cells in tissues).

Where do the pollutants come from?

There are a variety of sources that produce pollutants. Sources could be of natural origin or human activities. The primary source of human-made compounds is the chemical industry (e.g., industrial solvents, paints, adhesives, oil and petrochemical industries, household products, pesticides and fertilizers, fabric materials and furnishings). Regarding chemicals of natural origin, a good example are heavy metals that are present in the environment (e.g., arsenic, mercury, lead) apart from being the product of human processes.

How are pollutants produced?

Some pollutants can be produced naturally (e.g., forest fires or living organisms, most pollutants are produced through human activity. Examples include the manufacturing of paints, pharmaceuticals, and refrigerants. Other sources include petroleum fuels, hydraulic fluids, dry cleaning agents, and industrial solvents.


What groups are more susceptible to pollutants?

Children generally eat more food, drink more water, and breathe more per pound than adults. This means that children have the potential for greater pollutant intake compared to adults. The metabolism and defense systems of children are also not fully developed, which increases their susceptibility to chemical exposures. In addition, children’s bodies are growing and developing more rapidly; therefore, chemicals that affect developmental functions can be extremely damaging at this critical time.

Since children are exposed to pollutants as early as conception, in-utero development may be affected by compounds that enter the mother’s body via inhalation, ingestion, and/or dermal contact. Parents of infants and toddlers are challenged by children putting their hands and other objects into their mouths, which creates a concern of ingesting pollutants, such as pesticides, heavy metals, allergens, and allergens. The small stature of children potentially exposes them to volatiles that are low lying or emitted from carpet or other flooring, as well as those condensed in dust.

PCS Chemical Fact Sheets:

PCS Chemical Fact Sheets provide a summary of the properties of select chemicals. They cover basic information that is accessible to everyone. Currently, the fact sheets include chemical identity, where the chemical comes from, how we might be exposed to that chemical, potential health effects (signs and symptoms associated with exposures), and how we can reduce the exposure to that chemical. This basic information allows communities to be aware of the consequences of exposure to these chemicals. The list of environmental pollutants that produce adverse health effects is long. However, the following list contains chemicals that are common environmental pollutants, as well as pollutants that have the potential to be involved in emergency situations within Harris County, as referenced in the Project BREATH document:

In the case of occupational exposure, fact sheets have more detailed information. They are very useful to comply with the "right to know principle," providing workers with information and training that ensures their awareness of the chemical hazards used in their work area. 

What is the Project BREATH 2023 Resource Guide?

The Project BREATH 2023 Resource Guide, otherwise known as Project BREATH, was created to improve situational awareness and communication for various entities involved in an emergency event (e.g., responding agencies, community).  Project BREATH includes practices, existing plans, and frameworks used by emergency managers and responders in Harris County. To view the Project BREATH document, click on the image below (left). To view the Project BREATH disclaimer created by Harris County Pollution Control Services, Harris County Commissioner Precinct 2, and Houston Advanced Research Center (HARC), click on the image below (right).

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Project BREATH

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