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Lake Simcoe Region Conservation Authority

Skip Navigation LinksLake Simcoe Region Conservation Authority > Watershed Health > Chemical Contaminants

​Chemical Contaminants

Chemical contaminants are chemicals present in soil, air and water that are harmful to plants and animals. Though some may occur naturally, the majority of chemical contaminants enter the environment through industrial activities, discharge from wasterwater treatment facilities, manufacturing and usage of consumer products and agricultural activities.

Contaminants that are in our environment today can be classed into three categories; legacy contaminants, ​contaminants that are known to be problem​atic but are still in use today, and contaminants that are an emerging concern. A number of these pollutants have been observed, or are potentially present, in the Lake Simcoe watershed.​

Contemporary Pesticides

A pesticide is a substance used for preventing, destroying, repelling, or mitigating biological pests. Pesticides have provided incredible advantages in many ways by increasing crop yields and bolstering food availability. Unfortunately, their use can have unintended negative impacts. Contemporary pesticides are those that are currently used or have recently come under restriction in Ontario.​

Flame Retardants

Flame retardants are chemicals that can be applied to an object to make it resistant to catching fire. They are used industrially and can also be found on manufactured items such as couches, electronics and even baby toys. The chemical structures of flame retardants make them persistent (long-lasting) in the environment.​​​


Microplastics are small but potentially harmful plastic pieces that can have negative impacts on rivers, lakes, oceans, fish and other wildlife. Researchers are working to understand the extent of pollution and risks, including predictions of future microplastic abundance for both aquatic (water) and terrestrial (land) ecosystems.​

​Perfluoroalkyl Substances (PFASs)

​Perfluoroalkyl substances (PFASs) are commonly found in everyday products like non-stick frying pans and sprays used to provide stain resistance. They are also used in fire-fighting foam and in industries such as aerospace. PFASs are very persistent in the environment and in the human body – meaning they don't break down and they can accumulate over time.

Petroleum Hydrocarbons (PHCs)

Petroleum hydrobcarbons are commonly known as fossil fuels. They are found in essential everyday life products such as gasoline for cars and jet fuel. They are also used in creating materials like plastic, computers and MRI scanners. Contamination from PHCs is one of the most common types of soil and groundwater pollution in Canada.

Pharmaceuticals and Personal Care Products (PPCPs)

We use pharmaceuticals and personal care products every day. These common items include medications (both over the counter and prescription drugs), as well as soaps, detergents, cosmetics, perfumes and deodorants. These products provide us with many health benefits. However, there are growing concerns around their presence in our environment​. 


Phenols are used in the construction, automotive and appliance industries and are commonly found in household cleaners as disinfectants. Phenols do not tend to persist or accumulate in the environment. They are most dangerous and concerning when found in large quantities (such as from industrial spills).

Polychlorinated Naphthalenes (PCNs)

Polychlorinated naphthalenes were once used for cable insulation and preservation of wood, paper and textile products. PCNs have been phased out of use, but can be produced naturally as a by-product in combustion or emitted during metal refinement. Despite being largely phased out, their persistence in the environment continues.