September 10, 1999
To:Board of Health
From:Dr. Sheela V. Basrur, Medical Officer of Health
Subject:Environmental Health Issues in the City of Toronto
Purpose:
To provide a summary of the environmental health issues that can and do affect the residents of Toronto.
Source of Funds:
Not applicable.
Recommendations:
It is recommended that:
(1) the Board of Health receive this report and the attached background report entitled, "Environmental Health Issues in the
City of Toronto" for information;
(2) the Board of Health refer both reports to the Environmental Task Force for information.
Background:
In May 1998, the Health Promotion and Environmental Protection unit of Toronto Public Health was asked by the
Coordinator for the Environmental Task Force to provide information on the ways in which Toronto's environment can
and does affect human health.
Comments:
Attached is a report entitled "Environmental Health Issues in the City of Toronto", that provides a summary of the
environmental issues that may have a direct or indirect impact on the health of Toronto residents. The report is divided into
three sections: Air, Water and Land.
Air - Smog
The Air section highlights the environmental health issues related to smog, air toxics, global climate change, depletion of
the ozone layer, and indoor air. In Toronto, air levels of ozone and PM10, two of the primary indicators of smog, commonly
exceed the levels at which serious health effects have been demonstrated. Statistically significant increases in
hospitalizations have been observed at hourly ozone readings as low as 25 parts per billion (ppb). In 1997, the hourly
provincial standard of 80 ppb was exceeded 39 times at one sampling station in Toronto.
Statistically significant increases in death rates and hospitalizations have been demonstrated at daily PM10 readings as low
as 20 and 25 micrograms per cubic meter (ug/m3) respectively. In 1997, the maximum 24-hour reading in Toronto was 59
ug/m3 while the annual average of the daily PM10 readings was 24.5 ug/m3. In order for the annual mean to be 24.5 ug/m3,
the daily PM10 reading must frequently exceed this number. While sources of smog are varied, vehicle exhaust and
coal-fired generating stations in Ontario and the United States represent the major sources for southern Ontario.
One recent study has suggested that 4.6% of deaths in 11 Canadian cities, including Toronto, may be attributed to the
levels of nitrogen dioxide (NO2) in the ambient air. NO2 is a gas emitted when gasoline, coal, oil or natural gas are burned
as a fuel. In an urban centre such as Toronto, vehicle exhaust is the greatest source of NO2. Toronto has the highest levels
of NO2 of any city in Ontario. In 1996, the annual mean was 33.9 ppb while the highest 24-hour reading was 100.4 ppb.
Air - Other Issues
Benzene, formaldehyde and 1,3-butadiene are identified as three carcinogens that are known to be present at detectable
levels in Toronto=s air. In Toronto, as in urban centres across Canada, benzene is present at levels that many would
consider unacceptable. All three pollutants are emitted in vehicle exhaust.
Global climate change is identified as an environmental issue with the potential to profoundly affect the health of people
around the world. In Toronto, global climate change is expected to increase the number of deaths that result each year from
heat waves and other extreme weather events, while increasing the rate of chronic lung disease and heart disease in the
population. Global climate change is associated with the release of greenhouse gases such as carbon dioxide and methane.
Carbon dioxide is a gas released from any operation that involves the burning of fossil fuels such as oil, gasoline, coal and
natural gas. In Ontario, coal-fired generating stations are responsible for more than 20% of the province's carbon dioxide
emissions, which makes them the most significant point sources in the province.
Depletion of the ozone layer, associated with the release of ozone-depleting chemicals such as chlorofluorocarbons and
halons, is expected to increase health effects such as non-melanoma skin cancer by increasing the ultraviolet (UV)
radiation that reaches the earth. The number of days with high and extreme UV readings in Toronto has increased from
30-40 days in 1989 to approximately 60 days in 1995 and 1996.
There is increasing recognition that indoor air quality can have a significant impact on human health. This is particularly
true in northern climates where people spend most of their time indoors. Chemicals released from construction materials,
furnishings, and human activities in indoor environments, can accumulate to levels which exceed those in outdoor
environments and can produce both chronic and acute health effects for occupants. Biological agents such as bacteria,
mould, and dust mites that can be associated with humidifiers, damp construction materials, and mattresses, as well as
insects and pets, have been linked to health effects including respiratory infections such as pneumonia, allergies, and
aggravation of asthma. Toronto Public Health received more than 500 indoor air quality complaints in 1998.
Water C Drinking Water
The Water section of the report is divided into three sections; drinking water, persistent toxics, and water for recreational
use. In 1998, 100% of the 6,765 water samples collected from Toronto's drinking water complied with the province's
standards for biological contaminants. Of the 165 organic chemicals, 36 inorganic chemicals, and 107 pesticides for which
Toronto's drinking water is tested, only a handful are found at levels which warrant discussion; disinfection by-products,
aluminum and fluoride.
Disinfection by-products, such as trihalomethanes, are produced when chlorine is added to drinking water to kill biological
agents such as bacteria that can carry disease. In 1997, the level of trihalomethanes in Toronto's water averaged 13 ppb, a
level which is well below the federal guideline of 100 ppb. Aluminum is used in the water treatment process to remove
harmful biological agents and to reduce the formation of disinfection by-products. In 1997, aluminum levels in Toronto's
drinking water were maintained at an annual average of 0.077 mg/L, which is an improvement upon the operational
guideline of 0.1 mg/L recommended by the Federal-Provincial Subcommittee on Drinking Water. Fluoride is added to
drinking water to reduce the risk of dental cavities. Currently, fluoride levels are maintained at approximately 1.0 part per
million (ppm).
Two other water contaminants are discussed in the background report; lead which can enter the drinking water from lead
based or lead soldered pipes in the water distribution system or in residents' homes, and tritium which can be emitted from
the nuclear generating station in Pickering. While lead levels in flushed water are generally below the provincial guideline
of 10 ppb, lead levels in standing water can be significantly higher than the guideline. Tritium levels in Toronto's drinking
water are maintained between 8 and 12 becquerels per litre (Bq/L), which is well below the provincial annual guideline of
7,000 Bq/L, and also below the 20 Bq/L guideline recommended by the Advisory Committee for Environmental Standards
(ACES) in 1994.
Water - Persistent Toxics
More than 360 chemicals, about half of which are organochlorine compounds, have been detected in the Great Lakes
Basin. Many of these contaminants pose a serious threat to the ecosystem and to human health because they are persistent
in the environment and accumulate in the food chain. For those who live on the Great Lakes Basin, including Toronto
residents, the greatest route of exposure to these chemicals is through foods such as fish. Consumption restrictions, based
on the levels of chemical contaminants, apply to 9 out of 13 species of fish caught on Toronto's waterfront, and to 4 out of
6 species of fish caught off-shore from Toronto. In Lake Ontario, PCBs, mirex, mercury and dioxins are responsible for
50%, 27%, 22% and 1% respectively of these consumption restrictions.
Recent research has demonstrated that low level exposure to some of these persistent chemicals can have adverse effects
on the health of humans. Studies conducted on the children of women who ate Great Lakes fish during pregnancy have
demonstrated that low level exposure to chemicals such as PCBs and DDT can affect the immune systems of children, and
their intellectual ability, memory and behaviour. Toxicological studies and wildlife studies have also demonstrated that a
number of environmental pollutants have the ability to mimic hormones such as estrogen, and could be responsible for a
variety of disturbing health problems that have been observed in wildlife around the world.
Water - For Recreation
Toronto's 20 beaches are commonly posted with signs indicating that people should not swim when they become
contaminated with bacteria from run-off, over-flowing storm sewers, or sanitary sewers that have been historically
connected to storm sewers. The situation in the eastern beaches has improved since retention tanks were built in 1991 to
handle sewer over-flow in the east end. A storage tunnel is being built by the City to capture and treat sewer over-flow that
is considered responsible for much of the beach contamination in the west end of the city.
Land - Contaminated Soil
Because Toronto has been industrialized for more than a hundred years, past industrial activities have contributed to soil
pollution in some neighbourhoods. Toxics such as benzene, toluene, xylene, gasoline, PCBs, polycyclic aromatic
hydrocarbons (PAHs), and lead can be found in the ground, and sometimes in the groundwater, in some locations in
Toronto. These toxics can present a hazard to people who live, work or play at or around the contaminated site. Volatile
toxics such as gasoline can travel through the soil and accumulate in buildings on or beside a contaminated site. Toxics
such as lead can be ingested directly by children playing on the ground or indirectly by people eating food grown in
contaminated soil.
Soil can be a major source of exposure for toxics such as lead. Soil has become contaminated with lead from three
principle sources: emissions from vehicles operated on leaded fuel; emissions from local lead smelters; and dust from
weathering lead based paint. Lead levels in the blood of Toronto children has declined over the past 15 years because of the
elimination of leaded fuel and the reduced production from local lead smelters. Lead continues to be a public health
concern because health effects have been demonstrated at blood lead levels which are not uncommon in children today.
Today's exposure is related to lead which remains in homes and in the community from past practices.
Land - Physical Agents
Some environmental exposures of concern to the community include physical agents such as noise, the electromagnetic
field (EMF) surrounding power lines, radio towers and cellular phone transmission towers. Many studies have been
conducted on electrical workers and on people who live in close proximity to power lines to determine if the extra low
frequency (ELF) range of the EMF is associated with an increased risk of cancer, particularly childhood leukemia and/or
brain cancer. The results of these studies have been inconsistent and contradictory. In June 1999, the National Institute of
Health in the United States released a report that concluded that the EMF surrounding power lines "should be regarded as a
'possible carcinogen' because a role in cancer could not be ruled out". In light of the scientific uncertainty, many
jurisdictions, including the former City of Toronto, have adopted prudent avoidance policies.
In recent years, attention has turned to the electromagnetic field (EMF) associated with radio transmitters and cellular
phone transmission towers. While a good deal is known about the thermal or heating effects of this range of the EMF,
much less is known about the long-term effects of low levels of exposure.
Within an urban environment, noise can originate from many sources. While the relationship between noise and hearing
loss has been well recognized for many years, there is less consensus on how lower levels of noise, more commonly
experienced in an urban environment, may affect health. A Federal/Provincial Advisory Committee has acknowledged
however that environmental noise is more than just a nuisance; that it can produce serious physical and psychological stress
to which no one is immune. In 1998, approximately 1,300 noise complaints were investigated by the City of Toronto.
Land - Pesticides
Pesticides are one of the few toxic substances that we intentionally release into the environment. They are also one of the
few toxic substances that are used in environments frequented by children. Children are uniquely vulnerable to the harmful
effects of pesticides because of their physiological differences, developmental immaturity, and patterns of behaviour,
including patterns of food and fluid intake. For example, one study demonstrated that children playing on the floor can
inhale 4 to 6 times as much pesticide as an adult, and absorb through the skin, 30 times as much pesticide as an adult.
Recent studies also suggest that pesticides can persist longer in the indoor environment than previously believed because
there is no sunlight, rain or microbiological activity to speed their degradation. In one study, it was demonstrated that
chlorpyrifos, an organophosphate pesticide used to treat cockroaches, continued to accumulate on children=s toys and on
hard surfaces for two weeks after apartments were sprayed. In another study, the phenoxy herbicide, 2,4-D, used to treat
weeds, was found in carpets up to one year after the 2,4-D had been applied to the lawn.
In a review of 31 studies conducted on childhood cancer and pesticides between 1970 and 1996, childhood brain cancer
and leukemia were the two cancers most frequently studied with fairly consistent and moderate increases in risk. These
findings are significant in light of the increasing incidence of childhood cancers, particularly leukemia and brain cancer,
among Canadians.
It has been estimated that approximately 1.3 million kilograms of pesticides were applied by licensed applicators on lawns
in urban areas in Ontario in 1993. The amount of pesticides used in urban areas represents about one quarter of all the
pesticides used in Ontario for agricultural purposes.
In 1998, the City of Toronto as a corporation used approximately 1,900 litres of herbicides, 1,690 litres of glyphosate, 567
litres of fungicides, and about 60 kilograms of insecticides on general parklands, garden parks/horticulture, sports fields,
roadsides, golf courses/bowling greens, and trees. A strategy is currently being implemented to phase out the use of
pesticides on City green spaces in Toronto.
In 1998, six different pesticides were detected in either or both the Don and Humber Rivers: MCPP and 2,4-D, two
herbicides used on grass; diazinon, an organophophate insecticide used on lawns and gardens; atrazine and metolachlor,
two herbicides commonly used in agriculture; and cypermethrin, an insecticide used in gardens.
Implications for Action:
There is a substantial body of literature that suggests that a significant number of deaths, hospitalizations, and illnesses in
Toronto can be attributed to poor air quality. The sources of Toronto's air pollutants are many and varied. However,
vehicles operating in the Greater Toronto Area and coal-fired generating stations operating in Ontario and in the United
States are the most significant contributors. While the City must continue with the implementation of its Corporate Smog
Reduction Strategy, it must work with, and advocate for, aggressive action from senior levels of government. Air emission
caps for coal-fired plants in Ontario, provincial and federal funding for public transit and improved rail service in the
Windsor-Montreal corridor; and international discussions on nitrogen oxide emissions from coal-fired plants in the United
States, are all examples of the kind of action required.
While the human health links have not been so clearly documented for global climate change, we can predict that this
environmental issue could have an even more profound effect on life on this planet than all the other environmental issue
facing us. For this reason, it is essential that the City continue its ambitious campaign to reduce the release of greenhouse
gases within the City of Toronto and that it continue to advocate for more aggressive actions from senior levels of
government.
Indoor air quality is an area requiring more research on both the risk factors in indoor environments, as well as the policies
and regulatory tools needed to respond to health concerns in the community and to prevent such problems from developing
in the future.
There is a growing body of literature which demonstrates that human health can be affected by low level of exposure to
persistent toxics which are accumulating in our food chain. As a city with food banks working beyond capacity, it is ironic
that the fish in Lake Ontario, a high quality protein source that is readily available, must be eaten in limited quantities
because they are contaminated with persistent toxics. If we are working towards sustainable development in this City, then
surely the reclamation of this food source must be a priority. While it will take time to clear persistent toxics that have
accumulated in Lake Ontario from historical practices, there are actions that can be taken to reduce and eliminate present
and future releases of persistent pollutants. As a City, we have begun this process by incorporating a pollution prevention
policy in the proposed Sewer Use By-law and by phasing out sludge incineration at the Ashbridges Bay Sewage Treatment
Plant.
While the causal relationship between pesticides and cancer remains uncertain, there is a growing body of health literature
which suggests that there are reasons to reduce our use of, and reliance on, chemical pesticides. In recognition of this health
concern, City Council has adopted a policy to phase out the use of pesticides on city-owned parks and green space, and has
recognized the need for greater education of the public on both the hazards of, and alternatives to pesticides.
Conclusions:
There are a number of environmental issues that have the potential to impact upon the health of Toronto residents. Among
those for which the health effects have been most clearly documented are those related to air pollution, global climate
change, depletion of the ozone layer, and indoor air quality. While Toronto's drinking water appears to be extremely safe
from both a chemical and biological perspective, there is a need to monitor the health and technological issues related to
disinfection products such as trihalomethanes, aluminum, and fluoride, and a need for on-going education related to lead
that can enter drinking water from the distribution system.
Recreational use of Lake Ontario beaches continues to be seriously limited by contamination with bacteria from run-off,
over-flowing storm sewers, and sanitary sewers, although actions to be implemented over the next year promise to greatly
improve the situation. Consumption restrictions have been placed on a number of species of fish in Lake Ontario that have
been contaminated with persistent toxins such as PCBs, dioxin and mercury that can be harmful to human health and
particularly to the unborn.
Soil pollution from historical industrial and commercial activities is an on-going health concern for a number of
neighbourhoods within Toronto. Soil and dust contaminated with lead from the historical use of leaded paints and leaded
gasoline continues to present a health concern for children in older homes and urban areas. The health of Toronto residents
can be affected by pesticides used indoors and outdoors both by the City and by private residents within the City.
While there are uncertainties related to the human health effects of electromagnetic fields associated with power lines,
radio towers and cellular phone towers, there is ongoing research in this area which will be the subject of a future report.
Contact Names:
Kim Perrotta, MHSc
Environmental Epidemiologist
Health Promotion and Environmental Protection, Toronto Public Health
Tel: 416-392-1560 Ext. 8-7044
Fax:416-392-7418
E-mail: kperrott@toronto.ca
Connie Clement
Director, Public Health Planning and Policy
Toronto Public Health
Tel: 416-392-7463
Fax: 416-392-0713
Dr. Sheela V. Basrur
Medical Officer of Health
