How you are exposed to toxic chemicals


	The Toxic Nation Studies
	How you are exposed to toxic chemicals
	Why Now?

Where do toxic chemicals come from?

How do toxic chemicals get into our bodies?

What do toxic chemicals do in our bodies?

Why are children more vulnerable to toxic chemical exposure?

What does it mean if a chemical is persistent or bioaccumulative?

Where do toxic chemicals come from?

Industrial emissions
Agriculture
Consumer Products, Home Renovations and Diet

As a byproduct of many industrial processes, toxic chemicals are released from facilities into air, water and land. Some industrial sectors that produce and release toxic chemicals, such as dioxins, metals, and pesticides, include:

Electrical power generation		i.e. coal-fired power plants emit mercury, dioxins and furans, and components of smog such as nitrogen oxides and sulphur dioxide; emissions of carbon dioxide also contribute to climate change.

Chemicals manufacturing		Chemicals manufacturing refers to the production of a wide range of substances including petrochemicals, industrial gases, synthetic dyes and pigments, resin, synthetic rubber, artificial and synthetic fibres, filaments, pesticides, fertilizers and other agricultural chemicals, paint, coating, adhesives, soaps, cleaning compounds, and personal care products. Common pollutants emitted from chemicals manufacturing facilities include sulphur oxides, nitrogen oxides, VOCs, particulate matter, carbon monoxide, carbon dioxide, and dioxins.

Iron and steel manufacturing		i.e. steel mills produce iron from iron ore, coke and fluxing agents, which are then converted into refined steel; in the process of producing steel, facilities emit air pollutants such as hydrochloric acid, manganese compounds, phenol, naphthalene and benzene, as well as the greenhouse gas carbon dioxide.

Metal casting		i.e. foundries and die casting facilities produce a range of goods including automotive parts, jewelry and plumbing fixtures by pouring molten metal into molds; in the process of producing these goods, facilities emit organic air pollutants and metals.

Petroleum		i.e. petroleum refineries process crude oil into fuels like gasoline and diesel fuel, non-fuel products like lubricating oils and asphalt, and raw materials (i.e. benzene, toluene, xylene) for the chemical industry. In the process of refining crude oil into these various products, petroleum refineries emit toxics like particular matter, sulphur dioxide, nitrogen oxides, carbon monoxide and VOCs (benzene, toluene, and xylene).

Pulp and paper		i.e. paper mills process wood and wood fibre for use in paper products; this process involves digesting or cooking down wood material into a pulp and separating fibres from impurities, the pulp is then bleached, dewatered, pressed and rolled; emissions from these facilities include nitrogen oxides, sulphur dioxide, dioxins and greenhouse gases.

The agricultural sector uses an array of pesticides, insecticides, and herbicides to kill unwanted insects, plants and animals. Pesticides and other types of harmful chemicals used in agriculture contaminate the food we eat, as well as air, water and soil when they run-off from crops and enter the wider environment.

Canadians are also exposed to toxic chemicals everyday through commonly used products in the home, such as perfumes, shampoos, air fresheners, cleaning products, furniture and appliances, frying pans and food and beverage containers. To find out how you can avoid toxic chemicals in consumer products, visit the toxic-free home, and make a Chemical Reduction Pledge.

Particular activities, such as home renovations, are also a source of chemical exposure. Many paints, adhesives and carpets release high levels of volatile organic compounds; demolition can expose asbestos; and stripping old paint (pre-1960) can release lead into your household air.

Even our food can contain chemicals that are harmful to human health, either through pesticide sprays on fruits and vegetables, or by simply being grown in and around contaminated soil, air and water. In addition to pollutants found on fresh produce, 94 to 99 per cent of people's exposure to persistent organic pollutants, such as PCBs and pesticides, comes from diet, particularly the consumption of fish, fatty meats and dairy products.

How do toxic chemicals get into our bodies?

When toxic chemicals are released, either through industrial or agricultural processes or consumer products, they make their way into our bodies through:

the lungs (inhalation),
skin (dermal absorption), and/or
mouth (ingestion)—these are known as routes of exposure.

When chemicals are absorbed through these various routes of exposure they enter the blood stream and are carried around to different parts of the body. From the blood stream, chemicals are either stored in tissues, like fat and bone, or are metabolized by the liver, and excreted through urine, the lungs, sweat, semen, milk, saliva and bile. Infants can also be exposed to toxic chemicals through breast milk, but so far the benefits of breastfeeding outweigh the risk posed by toxins being transferred to the child.

What do toxic chemicals do in our bodies?

Once in the body, toxic chemicals can act in a variety of ways to harm human health.

Hormone disrupting chemicals, such as brominated flame retardants (BFRs) and phthalates, can mimic, block or interfere with hormones such as estrogen, androgen and the thyroid, resulting in reproductive defects, reduced fertility, and neurological, behavioural and developmental problems.

Carcinogenic chemicals can cause or aggravate cancer, which is the growth of abnormal cells that spread throughout the body, in some cases leading to death.

Neurotoxic chemicals fall into three main groups, heavy metals and metal compounds, solvents and other simple organic compounds, and pesticides. These chemicals cause damage to the brain and can lead to developmental and behavioural disabilities, particularly in children because their brains are still developing.

Respiratory toxins affect the breathing system. When these toxins are inhaled they affect the nasal passages, pharynx, trachea, bronchi, and lungs. These toxins cause both acute and chronic illnesses such as bronchitis, pulmonary fibrosis, emphysema, cancer, and general breathing problems. As irritants, respiratory toxins can also increase the severity and incidence of respiratory infections and can aggravate asthma.

Reproductive toxins can affect reproductive ability and sexual function. Examples of reproductive disorders that may be caused by these toxins include endometriosis, failure to ovulate normally, tubal pregnancies, miscarriages and still births (for women), and low sperm count and motility, undescended testes, hypospadius and testicular cancer (in men). Developmental toxins can negatively impact normal childhood development and growth, in both physical and mental terms.

Many chemicals can also damage the kidney, liver and other organs, as well as impair the immune system.

Why are children more vulnerable to toxic chemical exposure?

Even though children are smaller than adults, they actually consume more food and liquids and breathe more air per unit of body weight, which also means that they potentially ingest and absorb higher levels of toxic chemicals than adults in relation to their body size.

Particular physiological and developmental characteristics also make children more vulnerable to toxics once they have been exposed. Depending on age, a child’s ability to metabolize, detoxify and excrete chemicals can vary; and exposures at critical periods of development can cause irreversible damage to the nervous system, cause behavioural problems, suppress the immune system and damage reproductive organs.

Also, regular childhood behaviour places children in closer contact with potential sources of contamination, mainly because of their exploratory nature, frequent hand-to-mouth activity, and proximity to the ground.

What does it mean if a chemical is persistent or bioaccumulative?

Persistent compounds are not easily broken down in the environment and therefore stay in air, water and soil for a very long time—with a longer window of opportunity to be absorbed or ingested by people. As new persistent chemicals are created and released, there is an increase in the variety of pollutants that will be sticking around for decades, building up into quite the toxic soup.

Chemicals that bioaccumulate increase in concentration in the tissues of living organisms at higher levels than those found in the surrounding environment. These chemicals are very slowly metabolized and excreted, and tend to build up in the tissues of living organisms because the chemicals are drawn to biological fluids and tissues such as fats.

Toxic chemicals differ in terms of their persistence and capacity to bioaccumulate. Examples of some of the most notorious persistent and bioaccumulative chemicals include chlorinated hydrocarbons, such as DDT, PCBs and dioxins.

Another related phenomena is food-web magnification, which is the tendency for certain chemicals to accumulate in the highest concentrations in top predators, due to the ingestion of food sources contaminated with chemicals that are passed along and stored in fats.