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Additional burden of cancers due to environmental carcinogens in Newfoundland and Labrador: a spatial analysis

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Several environmental carcinogens are found to be spread across wide geographic areas, and the exposed inhabitants are at risk of developing various types of cancers. Arsenic and disinfection by-products in drinking water, ultraviolet rays from the sun, and agricultural chemicals used in golf courses were found to be the possible cancer risks. The study aimed to estimate the risks of cancer due to exposure to environmental carcinogens known to be present in wide geographic areas in Newfoundland and Labrador (NL). The NL cancer care registry provided 2008–2017 data (histological diagnosis, age, sex, and six-digit postal code) on cancers relevant to arsenic, disinfection by-products , ultraviolet rays , and agricultural chemical exposures. The geographic distribution of environmental carcinogens was collected from government sources and previous studies. Risk ratios (RR) of annual prevalence rates of cancers in high-risk (exposed to environmental carcinogens) and low-risk populations. For ultraviolet rays , arsenic, disinfection by-products , and agricultural chemicals, the RR (95% CI) were 1.5 (1.4–1.6), 1.25 (1.03–1.51), 1.8 (1.67–1.94), and 1.49 (1.3–1.7), respectively. An excess number of cancers in high-risk areas was possibly associated with exposure to environmental carcinogens . Public health regulations, environmental monitoring, health promotion, and increased awareness in high-risk areas can prevent exposure to environmental carcinogens.
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77
TECHNICAL ARTICLE
Additional burden of cancers due to environmental
carcinogens in Newfoundland and Labrador:
aspatialanalysis
Arifur Rahmana, Atanu Sarkara*, Jinka Sathyab, and Farah McCratec
aDivision of Community Health and Humanities, Faculty of Medicine, Memorial University, St. John’s, NL, Canada
bDiscipline of Oncology, Western University, London Regional Cancer Program, London, Ontario, Canada
cResearch and Innovation, Eastern Health, St. John’s, NL, Canada
Abstract: Several environmental carcinogens are found to be spread across wide geographic areas, and the exposed
inhabitants are at risk of developing various types of cancers. Arsenic and disinfection by-products in drinking water,
ultraviolet rays from the sun, and agricultural chemicals used in golf courses were found to be the possible cancer risks.
The study aimed to estimate the risks of cancer due to exposure to environmental carcinogens known to be present
inwide geographic areas in Newfoundland and Labrador (NL). The NL cancer care registry provided 2008–2017 data
(histological diagnosis, age, sex, and six-digit postal code) on cancers relevant to arsenic, disinfection by-products ,
ultraviolet rays , and agricultural chemical exposures. The geographic distribution of environmental carcinogens was
collected from government sources and previous studies. Risk ratios (RR) of annual prevalence rates of cancers in
high-risk (exposed to environmental carcinogens) and low-risk populations. For ultraviolet rays , arsenic, disinfection
by-products , and agricultural chemicals, the RR (95% CI) were 1.5 (1.4–1.6), 1.25 (1.03–1.51), 1.8 (1.67–1.94), and
1.49(1.3–1.7), respectively. An excess number of cancers in high-risk areas was possibly associated with exposure to
environmental carcinogens . Public health regulations, environmental monitoring, health promotion, and increased
awareness in high-risk areas can prevent exposure to environmental carcinogens.
Key words: environmental carcinogens, arsenic, disinfection by-products, ultraviolet rays, agricultural chemicals.
Introduction
e International Agency for Research on Cancer has identi-
ed more than 200 agents as carcinogenic (Group 1) and prob-
able carcinogens (Group 2A) to humans (IARC, 2019).
Environmental carcinogens are broadly dened as compounds
that are the subset of “known” and “reasonably anticipated”
human carcinogens and are considered nongenetic exogenous
factors that contribute to cancer risk (Sabo-Attwood et al.,
2006; WHO, 2011; Wogan et al., 2004).
In Canada, neoplasms rank at the top for all-age disability-
adjusted life year (DALY) counts and rates of age-standardized
DALY per 100,000 (Lang et al., 2018). A broad estimate in
Ontario has identied between 3,500 and 6,500 new cancer
cases each year as a result of exposure to 23 environmental
carcinogens (CCO, 2016). Some of these environmental
carcinogens are present in nature and are spread across wide
geographic areas, putting the entire exposed population at risk
of developing cancer. However, Canadas current cancer
prevention strategies have yet to pay adequate attention to
*Corresponding author: Atanu Sarkar (email: atanu.sarkar@med.mun.ca)
identifying and acting on the vulnerable population living in
areas with potentially high environmental carcinogen exposure.
Hence, health professionals have not been able to develop any
environmental carcinogen-specic cancer prevention strategies
in such high-risk areas. Also, local medical practitioners might
not have any scope to alert local health authorities on the
abnormally high prevalence of any cancer.
Newfoundland and Labrador (NL) has the highest age stan-
dardized incidence rate of cancer (587/100,000) (CCS, 2017).
Based on available environmental contamination data for NL,
four environmental carcinogens were found to be present in
wide geographic areas. ese were arsenic and disinfection
by-products in drinking water, ultraviolet rays from the sun,
agricultural chemicals (herbicides/fungicides/pesticides) in
ambient air, and (or) dusts aecting households living in close
proximity to a golf course (CAPE, 2016; CBC, 2019; de Leeuw,
2017; GoNL, 2012; Minnes & Kelly Vodden, 2017).
Arsenic is naturally present in underground sediments and
contaminates well water (GoNL, 2019a). e municipalities
have public water systems that treat raw water before supply and
regularly monitor its quality aer treatment (including arsenic).
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78 EHR, Vol. 63, Issue 3
erefore, it is unlikely that there is a high arsenic level in house-
hold taps supplying public water (omson et al., 2019). e
communities aected by arsenic in drinking water are usually
small in population size and do not have access to a public
water supply and rely upon their own artesian wells, and the
monitoring of water quality solely remains the responsibility
of the individual well owners (omson et al., 2019). us,
there are no ocial reports of arsenic levels in private wells
(GoNL, 2019a).
Disinfection by-products are a very complex group of
chemicals formed during the water-treatment process when
disinfectants such as chlorine are added to untreated or
partially treated raw water before removing organic matter
(CDC, 2016). ere are more than 600 disinfection by-
products in chlorinated tap water, though only two types of
disinfection by-products, i.e., trihalomethanes (THMs) and
haloacetic acids (HAAs) are regularly tested (Bull et al., 2011;
CDC, 2016). THMs and HAAs have been identied as weak
carcinogens (Group 2B, possible human carcinogen), and
they are oen used as a proxy for cancer risk assessment
(IARC, 2018; Nieuwenhuijsen et al., 2009; Salas et al., 2013;
WHO, 2004).
According to the Canadian Cancer Society, sunlight in
Canada is strong enough to cause skin cancer, one of the most
common types of cancers (CCS, 2020). NL is known for pro-
longed foggy weather, and thus there is a misconception that
there is a low risk of skin cancer due to a lack of direct sunlight
(CBC, 2019).
Golf courses are known for using various types of agricul-
tural chemicals (Golf ventures, 2019). In Canada, golf courses
were exempted by municipal bylaws that restrict use of agricul-
tural chemicals on private residential and municipal lands
(CAPE, 2016). Agricultural chemicals are heavily used on golf
courses, with four to seven times greater than the recom-
mended doses meant for any agricultural farms (Feldman,
2020; Golf ventures, 2019). In 2012, NL banned the use
andsale of some known carcinogenic agricultural chemicals
(2,4-dichlorophenoxyacetic acid, carbaryl, and 2-meth-
yl-4-chlorophenoxyacetic acid) on lawns, but golf courses were
exceptions (Band et al., 2011; GoNL, 2012, 2019b). Golf
courses are required to provide notice to all properties located
just within 15 m of the proposed agricultural chemical applica-
tion sites (GoNL, 2019b; VoPham et al., 2015). Several studies
conducted elsewhere found that populations living within
500m of agricultural farms are subject to airborne exposure to
agricultural chemicals due to dri (Bernardi et al., 2015; Golf
ventures, 2019; Ward et al., 2006). Agricultural chemicals are
also transported via dust particles from farmlands and are car-
ried away by strong winds. People are thus exposed to agricul-
tural chemicals by the inhalation of contaminated air and dust.
Furthermore, they are exposed to agricultural chemicals by
ingestion aer touching contaminated surfaces (by air and
dust) in and around their residences. However, except for
occupational (golfers, golf course maintenance workers) can-
cers, there is no published study that examined associations
between residential exposure to agricultural chemicals in pop-
ulations living in proximity to golf courses and a higher preva-
lence of the cancers caused by agricultural chemicals (Knopper
& Lean, 2004; Kross et al., 1996; Murphy & Haith, 2007;
Putnam et al., 2008).
We hypothesize that spatial distributions of environmental
carcinogens are associated with prevalence of related cancers.
e ecological study aimed to estimate the risks of cancers due
to exposure to ultraviolet rays, arsenic, disinfection by-products,
and agricultural chemicals.
Methods
Cancer data
Cancer data (histological and ICD code, age, sex, and geo-
graphic distribution (using six-digit postal code) from 2008 to
2017 were collected from the NL Cancer Care Registry
(NLCCR). e registry contains data at the population level on
cancer cases diagnosed in NL, and there was a near-complete
case ascertainment. e registry was queried using the relevant
data specications described above. e cancers (histological
types) known to have either of the four environmental carcino-
gens as risk factors were selected for our study (Table 1).
However, the NLCCR did not provide any background infor-
mation on the exposure history of the environmental carcino-
gens for the registered cancer cases, nor other risk factors such as
smoking, diet, occupational exposure, etc.
Selection of communities for each
environmentalcarcinogen
Ultraviolet rays
Daily ultraviolet index (UVI) monitoring data (1 March 2013
to 28 February 2019) for 37 meteorological centres of NL
were collected from Environment and Climate Change
Canada. UVI-6 was considered as high-risk level (protection
required to prevent sun burn and skin damage) (Health
Canada, 2018a, 2018b). e monitoring centres were ranked
according to the number of days having UVI-6 (or more)
during the data period (Health Canada, 2019). NL is known
for its cold climate and summer is the most popular season for
local outdoor activities. e UVI (for all the meteorological
centres) were high in summer (end of May to beginning of
September, i.e., ~100 days). e monitoring data show that the
days with UVI-6 (or more) were essentially found during sum-
mertime, for both the high-risk and low-risk centres. e cen-
tres having UVI-6 (or more) for ~100 days (and above) per
year were selected as high-risk centres, and the rest were
selected as low-risk centres. e communities located within a
50-km radius of each centre were selected for the study
(Figure1A) (Daly, 2006; Fioletov et al., 2004).
Arsenic
Ten high-risk communities (Cormack, Campbellton, Baytona,
Main Point, Fredericton, Deep Bay (Fogo Island), Bridge Port,
Carter’s Cove, Moretons Harbour, and Valley Pond) were
selected for the study. Arsenic in Cormack (population: 597)
was accidentally discovered during a community-based research
on the quality of private well water in 2011–2012. Arsenic was
discovered in nine other small communities (population range
83–615) by the personal initiative of a local family physician,
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Rahman et al. 79
who suspected high incidences of some cancers potentially
related to arsenic exposure (de Leeuw, 2017). e well owners
and the community members voluntarily shared 96 water qual-
ity reports, showing 55 samples above the guideline value of
10 parts per-billion (ppb) (range 11–1,040 ppb, average
150ppb) (GoNL, 2019a). As per the NL government’s policy,
public water is regularly tested for quality, including arsenic, and
the results are shared on its water portal (GoNL, 2020). Based
on the report, two communities (Gander and Twillingate, very
close to the high-risk communities), supplied by treated public
water were selected as a control (low risk) population. e cen-
sus data from 2016 show similar age and gender distribution in
high-risk and low-risk populations. Since certain types of skin
cancers (squamous cell and basal cell carcinomas) are also caused
by ultraviolet rays (Table 1), the background UVI of the high-
risk and low-risk communities were checked to ensure there was
no overlapping. All selected communities (arsenic exposed and
control) were low-risk UVI areas (Figure 1B).
Disinfection by-products
THMs and HAAs are the disinfection by-products regularly
tested four times a year by the NL government, and the reports
(2010–2016) were made available on the same water portal
(GoNL, 2020). Community-wise THM and HAA reports were
transferred to an Excel spreadsheet. e communities having
geometric averages of both THMs and HAAs above and below
guideline values (THMs-0.1 mg/L and HAAs-0.08 mg/L) were
selected as high-risk and low-risk areas, respectively (GoNL,
2019c). We have also identied the communities having either
only high THMs or only high HAAs. Arsenic and disinfection
by-products are the risk factors for cancers of urinary bladder
(transitional cell carcinoma and urothelial cell carcinoma) and
colon (adeno carcinoma) (Table 1). Since arsenic and disinfec-
tion by-products were found in private wells (communities not
supplied by public water) and public water systems, respectively,
there was no double exposure.
Agricultural chemicals
Out of a total 18 golf courses, nine have neighbourhoods sur-
rounding them, and four are located within the St. John’s metro-
politan area. In our study, the neighbourhoods located within
500 m of the boundary of nine golf course were selected as the
high-risk population (Bernardi et al., 2015). With the help of
the cartography department of the Memorial University library,
Table 1: Environmental carcinogens, target organs, and histological types of potential cancers
Environmental
carcinogens
Target organs Histological types of cancer
Ultraviolet rays Skin Melanoma, squamous cell carcinoma, basal cell carcinoma (Narayan et al., 2010)
Arsenic Urinary bladder Transitional cell carcinoma , urothelial carcinoma (CCS, 2007; Martinez et al., 2011)
Kidney Renal cell carcinoma (ATSDR, 2007; CCS, 2007)
Lung Squamous cell carcinoma (Martinez et al., 2011; Smith et al., 1992)
Skin Squamous cell carcinoma, basal cell carcinoma , Merkel cell carcinoma, Bowen’s
disease (ATSDR, 2007; Martinez et al., 2011)
Colon Adeno carcinoma (Stevens et al., 2008)
Liver Hepatocellular carcinoma, angiosarcoma (ATSDR, 2007; Smith et al., 1992)
Disinfection
by-products
(trihalomethanes,
haloacetic acids)
Urinary bladder Transitional cell carcinoma, urothelial carcinoma (Villanueva et al., 2004)
Colon Adeno carcinoma (IARC, 2011; Rahman et al., 2014)
Rectum Adeno carcinoma (IARC, 2011; Rahman et al., 2014)
Oesophagus Adeno carcinoma (ATSDR, 2007)
Liver Hepatocellular carcinoma (Lippmann, 2000)
Blood Acute myeloid leukemia, chronic myeloid leukemia (Infante-Rivard et al., 2001)
Lung Malignant mesothelioma (Melnick et al., 2006)
Agriculture
chemicals
Prostate Adenocarcinoma (Potti et al., 2003)
Kidney Renal cell carcinoma (Karami et al., 2008)
Lung Squamous cell carcinoma (Gallagher et al., 1996)
Blood and lymphatic
system
Acute myeloid leukemia , chronic myeloid leukemia, acute lymphocytic leukemia
(Bailey et al., 2015; Hernández et al., 2016), Non-Hodgkin’s lymphoma (Zahm &
Blair, 1992), multiple myeloma (Presutti et al., 2016)
Brain Non-astrocytic neuroepileptical tumour (Bassil et al., 2007)
Ovary Adeno carcinoma (epithelial cancer) (Shah et al., 2018)
Pancreas Adeno carcinoma (Andreotti et al., 2009)
Stomach Adeno carcinoma (Lee et al., 2004)
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80 EHR, Vol. 63, Issue 3
the high-risk areas around the golf course were demarcated and
each high-exposure risk area was further divided into six-digit
postal codes (Figure 2). For low-risk areas, we selected the town
of Conception Bay South (20 km from St. Johns, total popula-
tion 26,199), and 15 small coastal shing communities close to
the town of Conception Bay South (total population 9,088;
range 127 to 3,448) which have no golf course or agricultural
land within 5–6 km from their boundary. Census data (2016)
show no notable dierences in age and gender distribution
between high-risk and low-risk population. “Arsenic and agri-
cultural chemicals” and “disinfection by-products and agricul-
tural chemicals” were the common risk factors for renal cell
carcinoma and acute myeloid leukemia (AML) and chronic
myeloid leukemia (CML), respectively (Table 1). However,
there was no golf course in the communities aected by ground-
water arsenic. Also, disinfection by-product levels of the public
water sources in the communities having golf course were lower
than the guideline values (low-risk communities).
Data analysis
For arsenic, disinfection by-products, and ultraviolet rays, the
total populations of the high-risk and low-risk communities
were taken from 2016 census data produced by the Demography
Division of Statistics Canada (Statistics Canada, 2019). e
cancers (histological type) selected and analyzed for each
carcinogen category are listed in Table 1. To count the total
number of cancer cases in high-risk and low-risk communities,
we rst listed all the corresponding postal codes for each
community. en, we counted individual histological types of
cancers (listed in Table 1) for each carcinogen (arsenic,
disinfection by-products, and ultraviolet rays) and their
demographic backgrounds (age and sex) from these postal codes
and added them together.
To identify high-risk neighbourhoods around nine golf
courses, all the postal codes within the high-risk areas were
listed from the map (Figure 2). We mapped each high-risk
area using a high-resolution Google satellite map and counted
individual homes located in every postal code (Figure 3). For
the postal code areas that extended beyond the 500-m
boundary of the high-risk area, the entire postal code area was
included for counting homes. Large buildings, such as apart-
ment/condo complexes, were veried by browsing street view
images, which allowed us to count the actual number of apart-
ments or condos. e total number of houses in the high-risk
areas was multiplied by 2.3 (average household size of NL) to
Figure 1. (A) Meteorological centres with catchment areas (50-km radius) and their UV index (low and high); (B) Arsenic high-risk and low-risk
communities.
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Rahman et al. 81
generate the total population size (10,988) (Statistics Canada,
2019). Individual types of cancers due to agricultural chemi-
cals (Table 1) and their age and sex were collected from the
NLCCR according to the postal codes of the high-risk areas
and added together. For low-risk areas (town of Conception
Bay South and 15 small coastal shing communities), the
total population was obtained from the census, and from each
postal code for the town and small communities, the selected
cancer cases along with demographic backgrounds were
collected.
For each environmental carcinogen category, the number of
corresponding cancer cases was added together before calculat-
ing the average annual prevalence rates in high-risk and low-risk
communities, and, subsequently risk ratios (RR). To measure
signicance of RR, 95% condence intervals (CI) were
calculated.
e excess number of cancer cases in the high-risk population
associated with a specic environmental carcinogen was calcu-
lated by:
total number of cancer cases in the high-risk population –
average annual prevalence rate in the low-risk population ×
total population in the high-risk area.
Results
Table 2 shows that for all the environmental carcinogens, the
annual prevalence rates of cancers are signicantly higher in the
high-risk populations. e prevalence rates of cancer among
males were higher in all environmental carcinogen categories
(both in high-risk and low-risk areas). ere were no noticeable
dierences in average ages between high-risk and low-risk
categories.
Since the suns rays become stronger as we move south, UVI
also increases (Health Canada, 2018b). Figure 1A shows the
high-risk areas only in the southern part of the province; 280,034
people (i.e., 54% of total NL population) were from high-risk
areas. Estimated additional burden of cancer cases in high-risk
areas were 3,043 in 10 years (2008–2017). Potential arsenic-
exposed population in 10 communities was 2,876, i.e., almost
1,250 households (average household size of NL is 2.3 people)
(Statistics Canada, 2019). ere are an estimated 40,000 private
wells in NL that are operating without any information on
theirarsenic proles (Roche et al., 2013). If we go by the assump-
tion that each household owns one well, our surveyed popula-
tion covered only 3% of the well users. Nearly 412,000 people
Figure 2. High-risk neighbourhoods (~500 m wide) surrounding a golf course, with postal code areas.
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82 EHR, Vol. 63, Issue 3
Figure 3. High-resolution map showing neighbourhoods with postal code areas and homes.
Table 2: Risk analysis and cost analysis of cancers due to environmental carcinogens
Environmental carcinogens
Ultraviolet
rays
Arsenic Disinfection
by-products
Agricultural
chemicals
High-risk population 280,034 2,876 63,439 10,988
Cancer cases (10 years)a9,678 129 1,135 340
Prevalence rate ( per 100,000 people per year)
Total
346 449 179 309
Male 409 575 226 210b
Female 287 327 134 173c
Low-risk population 115,265 13,884 172,053 35,287
Cancer cases (10 years)a2,731 504 1,743 735
Prevalence rate (per 100,000 people per year)
Total
237 363 101 208
Male 289 466 129 149b
Female 186 264 75 95c
Risk ratio (95%CI) 1.5 (1.4,1.6) 1.25 (1.03,1.51) 1.8 (1.67,1.94) 1.49 (1.3,1.7)
Estimated additional burden of cancer in
high-risk populationd
3,043 (9,678 – 6,635) 25 (129 – 104) 493 (1,135 – 642) 112 (340 – 228)
aFor list of cancers for each enironmental carcinogen category (included in the analysis), refer to Table 1.
bAer remoing prostate cancer.
cAer remoing ovarian cancer.
dTotal (actual number of cases in high-risk – expected number of cases in high-risk area (based on prevalence rate in low-risk area).
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Rahman et al. 83
(79% of the total NL population) are served by the public water
system, and around 15% of the serviced population are at risk of
high disinfection by-products exposure (GoNL, 2016). It is
important to note that cancer prevalence rates in the communi-
ties, exposed to either high THMs or high HAAs, were not sig-
nicantly higher than the low-risk population (Table 3). It was
the rst evidence showing a high cancer prevalence rate in the
population living near the golf course.
Discussion
To the best of our knowledge, this is the rst of this kind of
population-based study in Canada that has tested hypothesis
of spatial associations between exposure to environmental
carcinogens and a higher prevalence of cancers. e major
strength of the study is its wide population coverage (both rural
and urban) and understanding of spatial distributions of
potentially high-risk populations. While the studies of ultraviolet
rays and disinfection by-products have covered almost the length
and breadth of NL, the study on agricultural chemicals has
covered all the golf courses located within communities.
Despite widely available environmental monitoring data on
ultraviolet rays and disinfection by-products, there are few pub-
lic health strategies addressing population vulnerabilities in
high-risk populations in NL. Due to existing regulatory mecha-
nisms, regardless of eorts by a rural physician to address the
arsenic contamination of private wells, there is no eective miti-
gation strategy in NL (Greenham, 2018). Higher prevalence of
cancers (specic to agricultural chemicals exposure) in the pop-
ulation living close to nine golf courses indicates signicant asso-
ciation. ere are 2,300 golf courses across Canada, and
prohibition of cosmetic use of agriculture chemicals on the golf
course is a contentious issue (Golf Canada, 2015; NGCOA).
Other Canadian provinces currently do not have any provincial
regulation controlling use of harmful agriculture chemicals for
golf courses (CNLA). Hence, many Canadians who live close to
a golf course are vulnerable to cancers and urgently need proper
risk assessment.
Cancers are not attributable to a single cause, and there may
be cumulative exposure to other risk factors. erefore, to prove
causal relations, future research should focus on testing bio-
markers, analyzing the body burden of environmental carcino-
gens, examining genetic damage pertaining to specic
environmental carcinogens and interviewing cancer survivors to
explore other risk factors/confounders/eect modiers relevant
to particular cancers such as the duration of exposure and resi-
dence, demography, smoking, occupation, economic status, eth-
nicity, family history of cancer, diet and water consumption
patterns, and co-exposure to other carcinogens (Madia et al.,
2019).
A well-planned strategy of combining regulation (mandatory
testing of private wells, improvement of public water treatment,
banning of the use of carcinogenic agricultural chemicals at golf
course), health promotion (application of sunscreen before out-
door activities in summer, low-cost water lters for arsenic, and
disinfection by-products and environmentally friendly turf-
care), and public awareness may eectively protect the high-risk
population from further exposure (CCME, 2007; Hirst et al.,
2012; omson et al., 2019).
e study has some limitations. First, the NLCCR data did
not have any information on other risk factors such as smoking.
erefore, our analysis assumed that independent risk factors in
both the high-risk and low-risk populations were the same.
Second, the NLCCR data did not include any potential
confounders/eect modiers (mentioned above). Hence, our
Table 3: Risk analysis of cancer due to disinfection by-products (2008–2017)
Risk analysis No.
High-risk population (both THMs and HAAs levels higher than guideline values) 63,439
Cancer cases (10 years) 1,135
Prevalence rate ( per 100,000 people per year) 179
RR (95% CI)a1.8 (1.67,1.94)
Population exposed to only high THMs 4,162
Cancer cases (10 years) 49
Prevalence rate per 100,000 people per year) 118
RR (95% CI)a1.16 (0.95,1.4)
Population exposed to only high HAAs 54,645
Cancer cases (10 years) 524
Prevalence rate (per 100,000 people per year) 96
RR (95% CI)a0.95 (0.86,1.05)
Low-risk population (both THMs and HAAs levels lower than guideline values) 172,053
Cancer cases (10 years) 1,743
Prevalence rate (_/100,000/year) 101
Note: THM, Trihalomethanes; HAA, haloacetic acids; RR, risk ratios.
aRR with low-risk population.
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84 EHR, Vol. 63, Issue 3
analysis was limited to spatial association only. We recommend
the regional health authorities collect information on exposure
to environmental risk factors relevant to any type of cancer while
examining the patients and to incorporate the information to
the existing electronic database. In this regard, proper orienta-
tion for the physicians are also needed to update knowledge on
potential environmental carcinogens present in NL.
Acknowledgment
e project was supported by the Seed, Bridge, and
Multidisciplinary Fund, Memorial University of Newfoundland
(2018). e research was approved by the Health Research
Ethics Board (HREB) (#2018:193) and the Research Proposals
Approval Committee (RPAC) of Eastern Health, NL (dated 23
October 2018).
Conicts of Interest
None declared.
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... Chronic exposure to disinfection byproducts (e.g., trihalomethanes (THMs) and halo acetic acids (HAAs)) in drinking water through ingestion, inhalation, and dermal contact increases the risk of adverse health effects. The International Agency for Research on Cancer (IARC) categorizes certain types of THMs and HAAs in Group 2B with the possible increase of the risk for liver cancers [1,2]. The US EPA suggests the maximum allowable levels of 80 ppb (parts per billion) for four THMs (THM4) (i.e., chloroform, bromoform, bromodichloromethane, dibromochloromethane) and 60 ppb for five HAAs (HAA5) (i.e., monochloroacetic acids, dichloroacetic acids, trichloroacetic acids, monobromoacetic acids, dibromoacetic acids) [3]. ...
... An increased level of NOM in the last two decades [4][5][6][7] due to global warming, acute raining, soil erosion [8,9], and water contamination has led to reduced or worsened effectiveness of water treatment processes by decreasing the lifespan of activated carbon pores [10]. Of the residents in Newfoundland and Labrador (NL), 79% are serviced by the public water distribution system, where 15 % of the consumers are in contact with high levels of THM4 and HAA5 in their drinking water [1]. The average of the dissolved organic carbon (DOC), a surrogate indicator of NOM content, in two-thirds of the surface waters of NL is more than 5 mg/L, with an average of 9 mg/L in some areas of the province. ...
... The ash and moisture content for CBPP-A10 are 3.62 ± 0.05 and 0.43 ± 0.05, respectively. 1 Data retrieved from previous studies [18,27]. A0: nitric acid (0% wt: wt), A5: nitric acid (5% wt: wt), A10: nitric acid (10% wt: wt), CBPP: Corner Brook pulp and paper fly ash, Diff.: metal removal (mol× 10 ) = A10, -,A5. ...
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