The Environmental Reporting and Disclosure Bylaw (PDF) lists the following 25 priority substances.

These priority substances are listed in the bylaw because they exist in Toronto’s air at levels of health concern.

Where are these chemicals used?

These chemicals may be used or released in a variety of operations, including chemical manufacturing, food and beverage production, automotive repair and laboratories. For example, trichloroethylene and dichloromethane are common cleaning solvents that may be used in sectors such as manufacturing.

Summary of health effects of each chemical

Acetaldehyde is possibly carcinogenic to humans. Risk to human health occurs when acetaldehyde in the air is inhaled. The entire human respiratory tract, including the lungs, is at risk for cancer induction by chronic exposure to low levels of inhaled acetaldehyde.

Possible sources: Acetaldehyde is used as an intermediate in the synthesis of other chemicals. It is a byproduct of incomplete wood combustion, pulp and paper production, stationary internal combustion engines and turbines and wastewater processing. It is also used in the production of perfumes, polyester resins and dyes. Acetaldehyde is used as a fruit and fish preservative, a flavouring agent, a denaturant for alcohol, in fuel compositions, for hardening gelatine, and as a solvent in the rubber and tanning industries.

Acrolein is primarily an irritant of the respiratory tract. Chronic exposure can lead to congestion of the respiratory system in addition to irritation of the eyes, nose and throat. Similar symptoms are displayed with short term exposure including tearing of the eyes, and irritation of the mucus membranes of the respiratory tract.

Possible sources: Acrolein is used as an intermediate in the manufacture of acrylic acid. It is used commercially and industrially in the formulation of herbicides, biocides, slimicides, and algicides; leather tanning, pharmaceutical production, and photography. Other sources include fossil fuel combustion, motor vehicle exhaust, tobacco smoke, burning of animal and vegetable fats, heating of lubrication oils, burning of wood and plastics, and aquatic and terrestrial pesticide use.

There is sufficient evidence to indicate that benzene is carcinogenic to humans. Chronic exposure to benzene leads primarily to disorders of the blood. Benzene is a cancer initiator that has been clearly linked to acute myeloid leukemia (i.e. a cancer of the blood system). Benzene can enter the body by inhalation, ingestion and absorption through the skin.

Possible sources: Benzene is a constituent in motor fuels. It is used as a solvent for fats, waxes, resins, oils, inks, paints, plastics, and rubber; in the extraction of oils from seeds and nuts; and in photogravure printing. It is also used as a chemical intermediate, in the manufacture of detergents, explosives, pharmaceuticals, and dyestuffs.

1,3-Butadiene is probably carcinogenic to humans. It has been linked to cancers of the blood and lymph systems, including leukemia. It has also been linked to disorders of the heart, blood and lungs, and to reproductive and developmental effects. Risk to human health occurs predominately when 1, 3-Butadiene is inhaled.

Possible sources: 1,3-Butadiene is used in the production of synthetic plastics and rubber. It is also a byproduct of manufacturing, processing, wastewater and combustion.

Cadmium

Cadmium and cadmium compounds are carcinogenic to humans. Cadmium is most clearly linked to lung cancer by inhalation. Kidney disease and damage have also been associated with exposure by ingestion as well as inhalation. Cadmium was identified as one of the top priority toxic substances using the TEP ranking approach.

Possible sources: Cadmium is released into air from zinc, lead, or copper smelting. It is also used to manufacture pigments and batteries and in the metal plating and plastics industries. It is also released as a result of burning fossil fuels and in the incineration of municipal waste materials.

Carbon tetrachloride is possibly carcinogenic to humans. Individuals chronically exposed to carbon tetrachloride may be at an increased risk of cancer of the liver. The primary route of exposure is inhalation, as a result of breathing air contaminated with carbon tetrachloride.

Possible sources: Carbon tetrachloride is used primarily as an intermediate in the manufacture of refrigerant. It is also used to a lesser extent as an industrial solvent and metal degreasing agent.

Chloroform is possibly carcinogenic to humans. Individuals chronically exposed to chloroform may be at an increased risk of both kidney and liver tumours. The risk of cancer is associated with exposure as a result of ingestion and inhalation of chloroform.

Possible sources: Most chloroform is used to manufacture HCFC-22 (a refrigerant for air conditioners). It may also be released into the air from a large number of sources related to its manufacture and use, as well as from its formation as a by product of chlorinating drinking water, wastewater and swimming pool water for disinfection purposes.

Chromium can be used and emitted in multiple forms. Hexavalent chromium (i.e. chromium VI) is much more toxic than other forms of chromium and it is the primary form emitted to air. Reporting of nonhexavalent chromium separately from hexavalent chromium enables the tracking of the different forms of chromium. During the industrial process one may convert to the other and emissions of non-hexavalent chromium are often associated with hexavalent emissions. Tracking of the different forms of chromium will stimulate pollution prevention activities in the areas that will afford the greatest risk reduction for Toronto residents.

Possible sources: Chromium is a metal used mainly for making steel and other alloys and it can be released during welding and cutting stainless steel. It also occurs in leather tanning, textile production, photography, stained glass working, chemicals used as a pigment in paints, inks, and plastics, as an anticorrosion agent in protective coatings, and in chrome plating.

Hexavalent and non-hexavalent Chromium

Chromium (VI) is carcinogenic to humans. It has been most clearly linked to lung cancer by inhalation in indoor and outdoor air.

Possible sources: Chromium is a metal used mainly for making steel and other alloys and it can be released during welding and cutting stainless steel. It also occurs in leather tanning, textile production, photography, stained glass working, chemicals used as a pigment in paints, inks, and plastics, as an anticorrosion agent in protective coatings, and in chrome plating.

1,4-Dichlorobenzene is possibly carcinogenic to humans. It has been linked to an increased risk of tumours of both the liver and kidneys. Individuals may experience this increased risk of cancer as a result of chronically breathing contaminated air containing 1,4-dichlorobenzene.

Possible sources: 1,4-Dichlorobenzene is used as an intermediate in chemical production, as a fumigant and a space deodorant.

1,2-Dichloroethane is possibly carcinogenic to humans. Individuals may experience this increased risk of cancer as a result of chronically breathing contaminated air containing 1,2- dichloroethane.

Possible sources: 1,2-Dichloroethane is primarily used in the production of vinyl chloride and other chemicals. It is also used as a solvent in closed systems for various extraction and cleaning purposes.

Dichloromethane is possibly carcinogenic to humans. It has been linked to an increased risk of tumours of both the liver and kidneys. Individuals may experience this increased risk of cancer as a result of chronically breathing contaminated air containing dichloromethane.

Possible sources: Dichloromethane is used as a solvent in paint strippers and removers. It is used as a process solvent in the manufacture of drugs, pharmaceuticals, and filmcoatings. It is also used as a metal cleaning and finishing solvent in electronics manufacturing; aerosol propellant, and as an agent in urethane foam blowing. Dichloromethane sources also include landfills and wastewater processing.

Board of Health Reports

In May 2016 the Board of Health requested the Medical Officer of Health to report back in 2017 on the implementation of a point-of-sale (POS) display program requiring all dry cleaners to clearly disclose to customers the types of solvents used to clean garments and any known hazards these solvents pose to public health. (See decision of the Board of Health)

In April 2007 the Medical Officer of Health reported to the Board of Health on the assessment of the health impact of the dry cleaning industry in Toronto, and the ways and means of ensuring that the dry cleaning industry eliminates harmful chemicals from its cleaning process. (See the report)

Regulations in other jurisdictions

New York State requires facilities that use tetrachloroethylene (or perc) to post a notice as described on the Department of Environmental Conservation website.

In 2014 the New York City approved a new regulation that requires dry cleaning establishments to post a sign which lists the primary chemicals used in their dry cleaning facility.

If adopted, Massachusetts bill on point-of-sale display program will require dry cleaning facilities to display a sign that lists the solvents used and include a color code.

The California Air Resources Board (the Board or ARB) amended the California Code of Regulations, Section 93109 to require dry cleaners to remove from service all perc dry cleaning machines by 2023.

Philadelphia’s Air Management Regulation XIV forbids the use or emission of perc in co-residential and co-sensitive facilities after 2013.

Perchloroethylene (perc)

Tetrachloroethylene has been listed as a toxic substance under the Canadian Environmental Protection Act.

Dry cleaners who use perc must comply with the Tetrachloroethylene (Use in Dry Cleaning and Reporting Requirements) Regulations (SOR/2003-79) administered by Environment and Climate Change Canada.

CAREX (CARcinogen EXposure) has developed profiles and estimates of occupational and environmental exposure for a number of known, probable, and possible carcinogenic agents. CAREX has identified Tetrachloroethylene as a priority environmental carcinogen

Alternatives to perchloroethylene (perc)

The Toxics Use Reduction Institute (TURI) conducted an alternative assessment of seven common alternatives to perc. An overview of the results of the assessment is found in the PERC Alternative Assessment Fact Sheet and more details in the full report.

Other resources

Environmental Defence issued the report, Removing the Stain, which outlines success stories and best practices for phasing out PERC from the US.
Toronto Environmental Alliance has information to help consumers identify environmentally-friendly options

Garment cleaning equipment manufacturers and suppliers

To get more information on garment cleaning equipment that operate with different cleaning solvents contact manufacturers or suppliers, for example:

Ethylene dibromide is probably carcinogenic to humans. It has been linked to an increased risk of a variety of cancers in many different organs. Individuals may experience this increased risk of cancer as a result of chronically being exposed to ethylene dibromide by any or all exposure routes. The exposure route of concern to TPH is breathing, as acceptable benchmarks for ethylene dibromide were exceeded in the air.

Possible sources: Ethylene dibromide is used as an intermediate for dyes, resins, waxes, and gums.

Formaldehyde is carcinogenic to humans. It is considered a weak initiator of cancer and a strong promoter of cancer. It is also a highly reactive substance that can be irritating to the nose, eyes, skin, throat and lungs at fairly low levels of chronic exposure. People with asthma may be more sensitive to the irritating effects of inhaled formaldehyde. Individuals may be at an increased risk of these health conditions after being chronically exposed to formaldehyde in the air.

Possible sources: Formaldehyde is used primarily to produce resins used in particleboard products and as an intermediate in the synthesis of other chemicals. It is released from stationary internal combustion engines and turbines, pulp and paper plants, and other manufacturing facilities. It may also be released when it is used as a fumigant, soil disinfectant, embalming fluid, and leather tanning agent.

Exposure to lead can lead to health effects in almost every organ and system in the human body, including adverse effects on the reproductive, gastrointestinal, renal, cardiovascular, hematopoietic, immune and nervous systems. These health effects are consistent regardless of the route of exposure (inhalation or ingestion). Chronic exposure mainly affects the nervous system. Symptoms of exposure may include a decrease in neurological function, and damage of the brain and kidneys. Children are especially vulnerable to lead poisoning. Recent science shows that even low levels of exposure to lead have adverse impacts on neurobehaviour in children and on blood pressure in adults. Lead is probably carcinogenic to humans. Exposure to lead may lead to an increased risk of cancer of the kidneys.

Possible sources: Lead is used in the manufacture of batteries. It can be released during combustion of solid waste, coal and oils, and during iron and steel production and lead smelting.

Manganese primarily affects the nervous system and neurobehavioral functions in humans. Individuals who are chronically exposed to manganese may experience impairment of motor skills such as difficulty performing fast movements and maintaining balance. TPH is concerned with population exposure as a result of individuals chronically inhaling air contaminated with manganese.

Possible sources: Manganese is used in the production of steel and alloys, batteries, matches, fireworks and as a chemical intermediate. It is also released into the air by combustion of coal and oil and by power plants.

Once mercury is released into the air it tends to settle in soil and sediments where it is changed to an organic form, methyl mercury, which biomagnifies or concentrates up the food chain, particularly the aquatic food chain. As a result, humans can be exposed to mercury (in the form of methyl mercury) when they consume fish and shellfish. Mercury is of concern to human health as it can have harmful effects throughout the body. Most notably, mercury is known as a potent human neurotoxin however, exposure has also been linked to an increased risk of reproductive toxicity and cardiovascular disease. Adverse effects on the nervous system are of increased concern for the fetus, infant and child as these subgroups are particularly vulnerable.

Possible sources: Mercury is used in the production of thermometers, barometers, batteries, dental amalgams, fluorescent lights and lubrication oils. It is also released in the combustion of fossil fuels in electric power generation.

Nickel compounds are carcinogenic to humans. Individuals who breathe in air contaminated with nickel are at an increased risk of developing diseases of the respiratory system. These diseases include chronic bronchitis, reduced lung function, and cancer of the lung and nasal sinus.

Possible sources: Nickel compounds are used for electroplating and the production of batteries, industrial plumbing, machinery parts, resistance wiring and chemical catalysts They are also released from utility oil and coal combustion, nickel metal refining, and lead smelting.

NOx is the term used to describe a category of chemicals known as nitrogen oxides. The main source of NOx is human activity as a result of combustion of fossil fuels particularly from vehicles. NOx is produced by all combustion processes in the presence of air. Nitrogen dioxide, NO2, was identified as one of five common air pollutants of significant health concern that contributes to the burden of illness from air pollution in Toronto. Individuals are exposed by inhaling air that contains NO2. NO2 affects mainly the respiratory system. Exposure leads to a decrease in the lungs’ ability to fight infection. Nitrogen dioxide concentrations are associated with daily mortality and hospital admissions as a result of respiratory disease. People with asthma and bronchitis, young children and adults with heart and respiratory disorders are especially sensitive to NO2 exposure.

Possible sources: Nitrogen oxides are released as a by-product of combustion and from some chemical processes.

Particulate matter (PM) is a term used to describe solid and liquid particles found in the air we breathe. These particles are composed of acid aerosols, organic chemicals, smoke, metal fumes, fly ash, dust and pollen. PM that is smaller than 2.5 microns in diameter is called PM2.5. PM2.5 leads primarily to irritation of the eyes, throat and lungs. These particles may worsen the condition of those individuals who are afflicted by respiratory conditions, such as asthma, bronchitis, or lung disease, and also affects those with pre-existing cardiovascular disease. Children and the elderly have an increased sensitivity to PM. Particles may also reduce an individual’s capacity to combat infection.

Possible sources: PM2.5 is released as a by-product of combustion and industrial processes.

Polycyclic aromatic hydrocarbons are a group of chemicals that are formed as a result of incomplete burning of organic substances. PAHs are present in the environment as complex mixtures that are difficult to measure and identify. Some PAH-rich mixtures are carcinogenic and some are not. Similarly, some individual PAHs are carcinogenic, and some are not. Benzo[a]pyrene (B[a]P) was used as a surrogate for the group of PAHs when determining cancer potency, because it is the most toxic member of the PAH family of compounds. Individuals may be exposed to a number of PAHs through both ingestion and inhalation. Although food is the major source of exposure to PAHs, since PAHs are a more potent carcinogen when inhaled than ingested, the risk of lung cancer due to inhalation exposure may be higher than the risk of stomach cancer from oral intake.

Possible sources: PAHs are released as a by-product of combustion and certain industrial processes. They are a component of asphalt, coal tar and other bituminous products.

Tetrachloroethylene is probably carcinogenic to humans. It has been linked to an increased risk of a variety of cancers in several systems of the human body, including both mononuclear cell leukemia and liver tumours. Individuals may experience this increased risk of cancer as a result of being chronically exposed to tetrchloroethylene by inhalation.

Possible sources: Tetrachloroethylene is widely used for dry-cleaning fabrics and textile processing. It is used as a chemical intermediate and in metal degreasing operations. It is also used in the manufacture of paint removers and printing inks, the formulation of adhesives and specialized cleaning fluids, and as aerosols and dye carriers.

Trichloroethylene is probably carcinogenic to humans. Individuals who are chronically exposed to low levels of trichloroethylene by inhalation, may experience an increased risk of liver, kidney or lung cancer. Chronic exposure may also lead to liver injury and acute central nervous system effects such as headaches and fatigue.

Possible sources: Trichloroethylene is used in industrial degreasing of metal parts, as a chemical intermediate, as an industrial solvent and in the production of consumer products such as paint strippers, adhesives and rug cleaning fluids.

Vinyl chloride is considered a human carcinogen. Exposure to vinyl chloride shows a strong and consistent association primarily with cancer of the liver. People may experience this increased risk of cancer as a result of breathing air contaminated with vinyl chloride.

Possible sources: Vinyl chloride is primarily used to make polyvinyl chloride (PVC) plastic which is then used to make a variety of plastic and vinyl products. A smaller portion of vinyl chloride is used in furniture and automobile upholstery, wall coverings, housewares and automotive parts.

VOCs are a group of organic chemicals that easily evaporate into the air from their direct use, from products containing them, or as a by-product of industrial processes. VOCs react with other pollutants to create ozone, a major contributor to smog. Ozone has been associated with acute symptoms like coughing and wheezing as well as more chronic conditions such as asthma and chronic obstructive pulmonary disease (COPD), which includes chronic bronchitis and emphysema. In 2004, TPH reported that exposure to five common smog pollutants, including ozone, contributed to about 1,700 premature deaths and 6,000 hospitalizations of Toronto residents each year. While VOCs can act as precursors of smog, they can also be toxic and impact directly on human health. People who chronically breathe air contaminated with VOCs may experience an increased risk of cardiovascular and respiratory problems.

Possible sources: VOCs easily evaporate into the air from their direct use, from products containing them or as by-products of industrial processes. Since there are many hundreds of VOCs it is somewhat difficult to summarize all possible sources. The most common sources however, include vehicle use, fossil fuel combustion, steel-making, petroleum refining, fuel-refilling, industrial and residential solvent use, paint application, manufacturing of synthetic materials (e.g. plastics, carpets), food processing, agricultural activities and wood processing and burning.