Document 1
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M E M O / N O T
E D E S E R V I C E
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Document 1
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M E M O / N O T
E D E S E R V I C E
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To / Destinataire |
Steve
Kanellakos
Deputy
City Manager, Community & Protective Services
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From / Expéditeur |
Dr. Robert
Cushman
Medical
Officer of Health
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Subject / Objet |
Update from the Medical Officer of Health on Cosmetic
Use of Pesticides
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Date: 19 August 2005 |
The Board of Health (City Council) has requested an update from the Medical Officer of Health (MOH) regarding the health effects of pesticides. Initially, this was to be released this fall prior to public consultation on the pesticide-free by-law. As those timelines fall after I leave the post of Medical Officer of Health to become the head of our Local Health Integration Network, I have made every effort to complete the work before my departure and am forwarding this information for you to present to City Council on my behalf.
Background:
In December 2002, after hearing many hours of public debate on whether to pass a by-law prohibiting the cosmetic use of pesticides on lawns and gardens, Ottawa City Council approved a three-year public education campaign to reduce pesticide use which included mass media advertising, workshops on using alternatives to pesticides and surveys of current practices. At the end of the three-year period, in the fall of 2005, City Council will discuss the implementation of a by-law prohibiting the cosmetic use of pesticides.
As has been stated, City Council, as the Board of Health, has also requested an update from the Medical Officer of Health (MOH) regarding the health effects of pesticides to help inform their debate.
This report provides a survey of the latest scientific evidence and offers the opinion of the MOH on the cosmetic use of pesticides, to be forwarded to the Board of Health for their consideration.
Review Methodology:
Research on the health
effects of pesticides is complex. Because we don’t yet have a clear
understanding of exposure risks, a variety of research on this matter must be taken
into account. Taken together, hundreds of studies on pesticide exposure paint a
disturbing picture. As much as we would like scientific exploration to be an
easy task, this is a complex issue, and no single study will provide all the
answers.
This report is not a full literature review, as that
is beyond its scope. However, two recent, comprehensive reports on the health
effects of pesticides are available. City Council, as the Board of Health,
should be aware of these studies and their conclusions.
·
Former
Toronto Medical Officer of Health Dr. Sheela Basrur, wrote an in-depth report
in 2002 following a review of the scientific literature entitled “Lawn and Garden Pesticides: A Review of Human
Exposure and Health Effects Research.”[1]
The Toronto analysis
concluded: “the evidence is persuasive
that the greater susceptibility of pregnant women and foetuses, infants,
children and the elderly justifies prudent avoidance and precautionary reasons
to limit unnecessary exposure to pesticides for these vulnerable
subpopulations.” Soon after this
report was released, the City of Toronto passed legislation to ban the cosmetic
use of pesticides.
·
In 2004, after
examining the results of hundreds of international studies, the Ontario College
of Family Physicians judged that
“evidence for harm is strong.”[2]
The College went on to publicize
warnings about pesticides and encourage its physician membership to advise
patients to reduce exposure to pesticides; supply information about organic
methods; educate on the high skin absorption of pesticides; and offer
instruction on the use of respirators for in home and occupational
exposures.
Included in this report is a
summary of relevant, methodologically sound studies offering new insights. Much
of the research is based on occupational studies, which are germane for several
reasons – many of the chemicals used on farms are also used on lawns and
gardens; occupational outcomes may serve as an advance warning to the
population as a whole; and pesticide appliers should be aware of the potential
health risks imposed by their jobs.
The research and policy
challenge is to determine to what extent findings from the occupational setting
can be applied to residential exposure rates. One cannot discount the
information on the grounds that the exposure is minimal by comparison. For
example, first, the volume of pesticides used per hectare in residential areas
has been found to be greater than that in agricultural areas.[3]
Second, residents may not protect themselves with safety equipment available to
workers. Third, evidence shows that certain people are more vulnerable to the
effects of pesticides (i.e. children, pregnant women and people with
environmental sensitivities), meaning that even a relatively small dose may
place them at greater risk for disease. And lastly, emerging literature on
residential exposures and exposures to specific pesticides used on lawns -
while in its infancy - has begun to identify disease risks such as a
miscarriages, birth defects, leukemia and Parkinson’s disease.
It is important to note that the following limits to
current research would tend to
underestimate health risks associated with pesticides:
·
Inadequate follow-up time – Because there is a long lag time between exposure and
disease, many studies simply don’t follow subjects long enough to get a full
picture.
·
No unexposed control group – As is made clear by body burden data, virtually everyone
is exposed to pesticides, making it difficult to find a study control group
from which to make a decent comparison.
·
A healthy worker effect – It is well known that people too ill to work leave the
workforce and thus are often excluded from occupational health studies. An
inherent bias exists because workers tend to be healthier than the general population.
·
Multiple exposures, multiple disease outcomes – The complexity of the
interactions makes it difficult to assess direct causal relationships. One
problem is determining which pesticides people have been exposed to. However, newer and more sophisticated
technology, such as measuring pesticides in umbilical cord blood, is allowing
for more targeted research. Furthermore, now that we know which diseases are
implicated, we can focus our research better.
·
Mortality vs. incidence – Most studies focus on death rates (mortality) and don’t
consider people surviving with a disease (incidence). In one of the few studies
measuring incidence, Florida researchers uncovered significantly elevated
incidences of three of the more treatable cancers - prostate, testicular and
cervical. (Fleming et al, 1999.)[4] With better diagnosis and
treatments available, adverse effects can be missed in morality-only studies.
Arguably, the history of
smoking may offer a parallel where the health impacts of second-hand smoke (a reduced
exposure) became known some 20 to 40 years after the effects of smoking
first-hand.
Finally, the current views of the federal Pest
Management Regulatory Agency were considered. A common line of reasoning is that since pesticides are legal, they must
be safe. This assumption ignores problems associated with our federal
regulatory agency, including chronic under funding and an over-reliance on
industry science.
City
Council should be aware that the Office of the Auditor General of Canada has
been extremely critical of the federal Pest Management Regulatory Agency. A 2003 audit said, “the federal government is
not adequately ensuring that many pesticides used in Canada meet current
standards for protecting health and the quality of the environment.”[5]
The
audit also reported that:
·
Health Canada has done
only limited research on the health effects of pesticides despite the federal
government‘s stated priority in this area. It has very limited dedicated
funding for research on human exposure to pesticides or the resulting health
effects. Three researchers are working on current pesticides, and they rely
primarily on outside funding. The Pest Management Regulation Agency did not
receive the funding it originally expected.
·
Required steps are not
always followed. Auditors found that evaluators often expedited the submission,
cut the scientific review short, or skipped the public consultation stage.
·
Progress made in
re-evaluating older, widely used pesticides has been very slow. In addition,
all pesticides re-evaluated were either removed from the market or had greater
restrictions placed on them.
·
For studies such as
toxicological assessments, potential registrants are to provide results
generated by laboratories inspected periodically by an independent body. There
were several examples noted when studies meeting such quality standards were
not provided.
·
Regulations stipulate
that temporary registrations may be approved for up to a year. Yet over the
last six years, more than 370 temporary registrations were extended and, in
most cases, more than once – some up to five times. “We are concerned about the
heavy and repeated use of temporary and emergency registrations,” stated the
auditors.
·
Agency staff assume
pesticides and users will follow label instructions, although the Agency’s own
compliance reports show that they may not. “Other studies have documented only
partial compliance with requirements to use personal protective equipment.”
·
In several cases,
measures listed on pesticide labels, even if followed, appear not to have been
enough to prevent environmental damage. For example, in P.E.I. more than 20
instances of fish kill since 1994 have been attributed to pesticides, with up
to 35,000 dead fish collected in each incident.
Discussion:
It
is worthwhile, at this point, to remind ourselves exactly what a pesticide is
and what it is designed to do.
Pesticides
are manufactured to interrupt biological systems and kill living species. This
is obviously a concern because humans share many genetic and physiological
characteristics with other organisms. Some pesticides inhibit important enzymes
of an insect’s nervous system; others upset the normal hormonal balance that
regulates cell division, protein synthesis, and respiration – important
functions at the micro level shared by all members of the plant and animal
kingdoms.
Pesticides
can have acute (short-term) or chronic (long-term) effects. Acute pesticide
poisonings underline the toxic nature of the chemicals. Such poisonings may
result in effects ranging from diarrhea to nerve damage. ‘Seizures are
characteristic of poisoning with 19 different pesticides and may occur with 12
others, including 2,4 D and the organophosphate and carbamate insecticides
commonly used on lawns and gardens.’ (Sanborn et al, 2002).[6]
These products were intended for
carefully applied industrial and agricultural use rather than as household
products for everyday purposes. No one can discount the contributions
pesticides have made in the modern age, such as reliable crop production and
malaria control. However, the question before the Board of Health is whether
cosmetic pesticide use is safe in residential settings where children play.
Vulnerable Populations:
a)
Prenatal and Children
Researchers
are learning that the timing of pesticide exposure is crucial in assessing
risk. ‘Critical exposure windows’ may include the months just prior to
conception or during pregnancy. The effects of exposure during pregnancy may
show up decades later; since a woman’s eggs are formed during fetal
development, a woman’s exposure could jeopardize the health of her grandchild –
creating a health hazard across three generations.
·
An American study
investigating cardiovascular malformations found a significant association
between pesticide exposure in the womb and a heart defect called transposition
of the great arteries. (Loffredo et al, 2001)[7].
·
Ma et al (2002)[8], investigating childhood leukemia, found that indoor
pesticide exposures early in life appeared to be more significant than later
exposures, and the highest risk was observed for exposure during pregnancy. It
must be noted that this study found no association with outdoor pesticide use –
the issue under discussion – but serves to illustrate the importance of timing
of exposure, raising questions about leukemia as a fetal disease in some
cases.
·
Several studies suggest
that the fetus clears toxicants less efficiently than the adult and may be more
vulnerable to genetic damage and the resultant risk of cancer. In addition, the
human nervous system involves an “exquisitely sensitive process. . . the
production of 100 billion nerve cells and 1 trillion glial cells, which then
must follow a precise stepwise choreography,” writes Perera et al (2002)[9].
“A mistake at any one step can have permanent consequences.”
·
Children, too, are
disproportionately affected. For instance, their hand-to-mouth behaviour and
play on the ground increases exposure; their organs are immature and therefore
can’t manage toxins as well; and their longer future life span allows more time
for diseases to arise. (Note also that people and pets track pesticides indoors
on their shoes, inadvertently exposing children).
b)
Vulnerable gene traits
People
with certain gene traits called ‘polymorphisms’ seem more susceptible to the
harmful effects of pesticides. This ‘polymorphism’ phenomenon has been studied
on the pesticide question, as illustrated by the following examples:
·
A Montreal study looked
at children exposed in the womb to residential (including outdoor) pesticides
and found they were at higher risk for childhood leukemia when they carried
certain gene mutations that lower one’s ability to detoxify cancer-causing
agents (Infante-Rivard, 2001)[10].
·
For people exposed to
pesticides in gardening and professional use, the risk of Parkinson’s disease
was increased two-fold among those with ‘poor-metabolizing’ genes. (Elbaz et
al, 2004)[11]. These ‘poor metabolizers’ have difficulty ridding
their bodies of specific poisons including pesticides. The study also noted that
in the absence of pesticide exposures, ‘poor metabolizers’ were not at
increased risk for Parkinson’s disease.
Since we currently have a
limited understanding of genetic polymorphisms, and because these particular
gene mutations are relatively common, it is important to protect the population
as a whole.
Synergism:
·
Complicating the
picture is that regulators do not adequately study the many chemicals
associated with the manufacture and environmental breakdown of pesticides.
These include formulants (non-active ingredients), breakdown products and
contaminants from the manufacturing process such as dioxins.
·
Additional risk factors can place a person in the vulnerable category. A
good example is an investigation by Alavanja et al (2003)[13],
who discovered that ‘significant associations between specific pesticides and
prostate cancer risk were observed largely among those with a family history of
prostate cancer.’ This finding is important because prostate cancer is the most
common malignancy among Canadian men, and despite its common occurrence, its
cause remains largely unknown.
Genotoxicity:
It
is increasingly recognized that many diseases are the result of complex
gene-environment interactions. In fact,
a number of research studies have found an association between pesticide
exposure and genotoxicity (DNA damage). Such damage may be a precursor to
cancer and other illnesses. Since genes are the human blueprint, the
relationship between genotoxicity and pesticide exposure is concerning and
needs further exploration.
·
For instance, Garry et
al (1996) found that pesticide appliers were more likely to have specific
chromosomal breaks and ‘rearrangements’ that are associated with cancer risk[14].
·
Another study analyzed
the DNA of greenhouse workers and concluded these workers had significantly
more chromosomal aberrations just after a summer season of spraying compared to
pre-season, especially among those who had not worn gloves (Lander, 2000)[15].
While cancer risks are most
often related to pesticide exposure, reproductive (including male and female
exposure) and neurological outcomes are equally worrisome. The neurological
findings are compelling, and in an era of rising infertility concerns, we
should pay particular attention to the reproductive studies. For example:
·
A Dutch study found that high farming exposure to pesticides during the
spraying season made it more difficult for a couple to conceive. The measure of
fertility used in the study, called ‘time to pregnancy,’ was normal outside the
spraying season (de Cock, 1994)[16].
·
Weidner et al[17]
found higher rates of chryptorchidism (undescended testes) to sons of women
working in gardening. The researchers hypothesized this could be attributed to
hormonal effects of pesticide formulations.
·
Men in France occupationally exposed to pesticides were five times more
likely to get Parkinson’s disease and twice as likely to get Alzheimer’s
disease (Baldi et al)[18].
·
A literature review found that of 14 studies on the relationship between
pesticide exposure and Parkinson’s disease, 11 found a positive association. (Priyadarshi et al)[19].
It is
now well established that poisoning by a toxin called MPTP, similar in
structure to a number of pesticides, results in a syndrome strikingly similar
to Parkinson’s disease. The authors
concluded, “Since Parkinson’s disease may be occurring at a younger age at
onset, perhaps because environmental risk factors are becoming more common,”
there is a need for more sophisticated research.
New information on the potential
additive effects of chemicals in the human body should be considered when
assessing the potential hazards of pesticides.
·
Data
from the U.S. Centers for Disease Control and Prevention (CDC) revealed a high human
pesticide ‘body burden.’ The study found that the average person has 13
pesticides in their body, and almost everyone has a breakdown product of the
long-banned DDT[20].
·
More
recently, a study conducted by the Environmental Working Group entitled “Body
Burden – the Pollution in Newborns” – tested umbilical cord blood of 10
newborns and detected 287 industrial chemicals (including pesticides)[21].
Conclusion:
Arriving
at decisions on important community health issues, including the pesticide
issue, requires not only a regulatory framework, but also a discussion of
underlying ideas. The following principles serve as a useful guide:
1) The Precautionary Principle
This principle, enshrined in international law, says
that where potential risks outweigh benefits, scientific uncertainty should not
be used as a reason to postpone taking action to protect health. It is
increasingly recognized that ‘precaution’ should be based on scientific
principles and viewed as an overarching societal philosophy.
“Physicians are taught ‘primum non nocere’ (first of
all, do no harm),” writes Dr. Neil Arya in a recent edition of the Canadian
Journal of Public Health,
“Environmentalists seek the same basic protection for
the ecosystems on which we depend for survival i.e. the Precautionary
Principle. . . the obligation should not be on citizens and their
representatives to demonstrate harm, but rather on those introducing new
products to society to prove not only that the products themselves are safe,
but that clean production processes are used with insignificant discharge of
foreign, noxious substances. This is known as ‘Reverse Onus.’ These conditions
are not met by currently used pesticides.”[22]
An understanding of past errors is important. For
example, herbicide spraying decades ago at CFB Gagetown has allegedly resulted
in serious illnesses among personnel and residents exposed. (Incidentally, many
of the first-generation pesticides have been pulled from the market for safety
reasons; whether newer pesticides will suffer the same fate remains to be
seen). In future, the precautionary principle will help us avoid similar
incidents.
2) Risks vs. Benefits
From a public health perspective,
the potential risks outlined in the discussion section above far outweigh the benefits,
especially given that both the industry and individuals can use pesticide-free
alternatives.
3) “Second-hand” effects
Pesticides do not stay put – so one person’s actions
may significantly impact on another person’s health and well-being. Pesticides
drift into the air, seep into soil, and leak into our streams and rivers. In
2003, the Rideau River and its tributaries tested positive for a number of
landscaping pesticides, including the particularly hazardous (and recently
banned) neurotoxin diazinon.[23]
Ottawa
City Council has a vital role to play with respect to this issue, particularly
because of its dual role as Board of Health. In addition:
·
The cities of Montreal, Toronto, and Halifax have already adopted
pesticide-free by-laws. In fact, the
Province of Quebec’s 2003 Pesticide Management Code (over three years) banned
the use numerous pesticides including 2,4 D, MCPA and mecoprop on public,
private and commercial lawns and prohibited the sale of these lawn pesticides,
as well as fertilizer-pesticide mixtures. When the pesticide industry protested
the first ban in Hudson, Quebec, the Supreme Court ruled in favour of the
municipality, arguing that local governments best understand the health needs
of communities.
·
A
2004 international study concluded that pesticide-reduction education and
outreach programs are much less effective than pesticide by-laws. In fact, only
those communities that passed a by-law and supported it with education were
successful in reducing the use of pesticides by a high degree (51-90%). The
researchers could not find an education/ outreach program that achieved more
than a low reduction (10-24%) in pesticide use.[24]
Aggregate scientific
evidence and the precautionary principle support the need for a cosmetic
pesticide prohibition in Ottawa. While the City's three-year pesticide education
strategy has been helpful, it has not resulted in adequate reduction of
cosmetic pesticide use on lawns and gardens. Much more research is needed
before conclusive evidence is available on this issue; however, the balance of
research published to date urges extreme caution.
Therefore, as Medical
Officer of Health, I recommend that Ottawa City Council pass a by-law to
prohibit the cosmetic use of pesticides on lawns and gardens, to be implemented
March 2006. Agricultural and forestry use should be exempted, as this does not
qualify as cosmetic use.
______________________________________
cc: Kent
Kirkpatrick, City Manager
Dr. Dave Salisbury, Acting Medical Officer
of Health
[1] Basrur, S. Lawn and garden pesticides: a review of human exposure and health effects research. Toronto Public Health, April 2002.
[2] Sanborn M, Cole D, Kerr K, Vakil C, Sanin LH, Bassil K. “Pesticide Literature Review,” Ontario College of Family Physicians, 2004.
[3] Pim L, Cooper K, Keenan K. “Urban versus agricultural: pinning down the numbers on pesticide use.” Intervenor vol. 27, no. 1-2, Jan-June 2002.
[4] Fleming LE, Bean JA, Rudolph M, Hamilton K. Cancer
incidence in a cohort of licensed pesticide applicators in Florida. Journal of Occupational & Environmental
Medicine. 1999; 41: 279-288.
[5] “Managing
the Safety and Accessibility of Pesticides,” Office of the Auditor General of Canada, Report of
the Commissioner of the Environment and Sustainable Development, 2003. www.oag-bvg.gc.ca
[6] Sanborn, MD, Cole D, Abelsohn A, Weir E. Identifying and managing adverse environmental health effects: pesticides, CMAJ 2002; 166(11):1431-6.
[7] Loffredo CA, Silbergeld EK, Ferencz C, Zhang J. Association of transposition of the great arteries in infants with maternal exposures to herbicides and rodenticides. Am J Epidemiol 2001; 153:529-36.
[8] Ma X, Buffler PA, Gunier RB, Dahl G, Smith MT, Reinier K, Reynolds P. Critical Windows of Exposure to Household Pesticides and Risk of Childhood Leukemia. Environ Health Perspect 110:955-960 (2002)
[9] Perera, FP, Illman SM, Kinney PL, Whyatt RM, Kelvin EA, Shepard P, Evans D, Fullilove M, Ford J, Miller RL, Meyer IH, Rauh VA. The challenge of preventing environmentally related disease in young children: community-based research in New York City. Environ Health Perspect 110:197-204 (2002).
[10] Infante-Rivard C, Labuda D, Krajinovic M, Sinnett D. Risk of childhood leukemia associated with exposure to pesticides and with gene polymorphisms. Epidemiology 1999; 10(5):481-487.
[11] Elbaz A, Levecque C, Clavel J, Vidal JS, Richard F, Amouyel P, Alpérovitch A, Chartier-Harlin MC, Tzourio, C. CYP2D6 polymorphism, pesticide exposure, and Parkinson’s disease. Ann Neurol 2004; 55:430-434.
[12] Arbuckle TE, Lin Z, Mery LS. An exploratory analysis of the effect of pesticide exposure on the irsk of spontaneous abortion in an Ontario farm population. Environ Health Perspec 2001; 109:851-857.
[13] Alavanja MC, Samanic C, Dosemeci M, Lubin J, Tarone R, Lynch CF, Knott C, Thomas K, Hoppin JA, Barker J, Coble J, Sandler DP, Blair A. Use of agricultural pesticides and prostate cancer risk in the agricultural health study cohort. American Journal of Epidemiology. 2003; 157(9): 800-14.
[14] Garry VF, Tarone RE, Long L, Griffith J, Kelly JT, Burroughs B. Pesticide appliers with mixed pesticide exposure; G-banded analysis and possible relationship to non-Hodgkin’s lymphoma. Cancer Epidemiology, Biomarkers & Prevention. Vol 5, 11-16, 1996.
[15] Lander BF, Knudsen LE, Gamborg MO, Jarventaus H, Norppa H. Chromosome aberrations in pesticide-exposed greenhouse workers. Scand J Work Environ Health 2000; 26: 436-442.
[16] De Cock J, Westveer K, Heederik D, te Velde E, van Kooij R. Time to pregnancy and occupational exposure to pesticides in fruit growers in The Netherlands. Occup Envion Med 1994; 51:693-699.
[17] Weidner IS, Moller H, Jensen TK, Skakkebaek NE. Cryptorchidism and hypospadias in sons of gardeners and farmers. Environ Health Perspect 106:793-796 (1998).
[18] Baldi I, Lebailly P, Mohammed-Brahim B, Letenneur L, Dartigues JF, Brochard P. Neurogenerative diseases and exposure to pesticides in the elderly. Am J Epidemiol 2003; 157; 409-414.
[19] Priyadarshi A, Khuder SA, Schaub EA, Priyadarshi SS. Environmental risk factors and Parkinson’s disease: a metaanalysis. Environmental Research Section A 86, 122-127 (2001)
[20] U.S. Centers for Disease Control and Prevention, “Second national Report on Human Exposure to Environmental Chemicals,” Jan. 2003
[21] Environmental Working Group, “Body Burden – The Pollution in Newborns,” July, 2005.
[22] Arya, N. Pesticides and Human Health – Why
Public Health Officials Should Support a Ban on Non-essential residential use, Canadian Journal of Public Health,
March-April 2005.
[23] City of Ottawa Water Environment Protection Program, “Surface Water Pesticide Monitoring Program” Summary 2003-04.
[24] Cullbridge Marketing and Communications and
Canadian Centre for Pollution Prevention. “The impact of by-laws and public
education programs on reducing the cosmetic/non-essential, residential use of
pesticides, A best practices review,” 2004.