Chlorine and chlorinated derivatives are under increasing scrutiny
and have become the subject of public policy debate. Concern about
chlorine centres around the fact that a few chlorinated compounds,
such as PCBs and DDT (production now banned) are persistent, toxic
and bioaccumulative. Historical manufacturing and use practices
have allowed these compounds to accumulate in the environment and
their effect on wildlife has been documented. Recently, allegations
have been made regarding possible adverse health effects of these
types of chlorinated compounds.
There are many thousands of chlorine-based chemicals that are not
bioaccumulative persistent toxics. Chlorine, in addition to its
use in water purification, is used to make many of the products
we use every day, including 85% of all pharmaceuticals. C4 supports
Environment Canada's Chlorinated
Substances Action Plan which calls for more research into possible
health effects and states that "not all chlorinated substances or
uses of chlorine pose a threat to the health of Canadians or the
environment... The government is committed to the virtual elimination
from the environment of the most persistent toxic bioaccumulative
substances, including chlorinated substances."
One of the principles of C4 is to promote science-based decision-making.
Accordingly, a major part of the organization's activities and budget
are devoted to a program aimed at doing the research which will
enable society to make sound science-based decisions regarding the
use of chemicals. In order to determine research priorities, C4
assembled a Science Advisory Group consisting of university, hospital
and government scientists. They provided advice on research already
underway and identified research gaps.
The following projects have been funded by C4 as of June 2002.
C4 Research Projects: Descriptions, Progress
Summaries,
and Completion Statements June 18, 2002
A brief project description and an overview of the results to
date are presented. For completed projects the results section
is replaced by a completion statement and an opinion statement
from C4 on the scientific significance of the findings relative
to chlorine chemistry issues is added. A * at the beginning of
the title indicates that there has been an update, revision or
addition since the April, 2001 version of this report.
1. Chair in Environmental Modeling, Trent University. (95-A,
95Ab)
This government and industry-sponsored chair for Dr. D. Mackay
allows him to continue to develop, enhance, and apply computerized
environmental fate models for use in assessing, evaluating, and
regulating both existing priority chemicals and new substances.
Funding for the chair has been extended for a second 5-year term
(2000-2005). (Completed the first 5 year term).
Dr. Mackay and his associates continue to develop and expand
collaboration and communication with industry, government, and
academia though meetings and workshops as well as distribution
of a semi-annual newsletter. A web site is maintained where computer
models developed at the Canadian Environmental Modeling Centre
are distributed free of charge. Considerable progress has been
made in several areas of research on the environmental fate of
chemical. In addition to presentations at a variety of national
and international scientific meetings, a number of articles have
been published or accepted for publication in various scientific
journals or monographs.
In addition to assisting in expanding the world-class contributions
of Dr. Mackay and his associates to the technical knowledge base
on the environmental fate of chemicals, the first term of this
project has contributed to the development of the Canadian Environmental
Modeling Centre as an international communication forum for scientific
issues and approaches about the environment fate of chemicals
whether chlorinated or not.
List
of Reports and Publications
2. Systematic Assessment of Estrogenic Substances.(95-B)
Dr. T. Zacharewski and associates of the University of Western
Ontario (moved to Michigan State University in 1997) examined
certain natural and man-made compounds, both chlorinated and nonchlorinated,
to determine if they produce some effects similar to the female
hormone estrogen. (Completed)
Results from both in vitro and in vivo testing
of various natural substances (naringenin, quercetin, biochanin),
environmental pollutants (dioxins, PCBs and hydroxolated PCBs,
o,p'-DDT, PAHs), pharmaceuticals (diethylstilbestrol, ethynyl
estradiol, norgesterol, tamoxifen, and industrial chemicals (phthalate
esters, alkylphenols, bisphenol A, endosulphan, triazenes atrazine,
simazine) and complex mixtures (pulp and paper mill effluents
and black liquor, sediments, and urban air particulates) indicated
a substantial number of these substances are capable of binding
to the estrogen receptor and inducing an estrogenic response.
Environmental estrogens (excluding drugs) were found to be significantly
less potent than natural female sex hormone. Biochemical assays
conducted with cell or tissue extracts or components may not accurately
predict whole organism responses due to their inability to replicate
the uptake and distribution interactions that occur whole organisms.
This suggests caution should be exercised when attempting to interpret
and extrapolate from rapid endocrine screening tests.
This project, co-ordinated with the project of Dr. van der Kraak,
has improved understanding of endocrine disruption in mammals
and fish by studying a number of natural substances, environmental
pollutants, pharmaceuticals, and industrial chemicals, some of
which are chlorinated. For effects associated with reproductive
hormones, it was concluded that caution must be exercised when
extrapolating between biochemical tests and whole organisms and
between different types of organisms.
List
of Reports and Publications
3. Reproductive and Endocrine Toxicology in Fish. (95-01)
Dr. G. van der Kraak and associates of the University of Guelph
investigated the environmental effects of a number of chemicals,
using fish biochemical tests and effects on fish reproduction.
(Completed)
This work focused on the mechanisms of how chemicals produce
reproductive and endocrine effects in fish. A number of chemicals
and complex mixtures were tested for estrogen and androgen receptor
activity using various fish cell culture techniques. Whole fish
testing was used determine if in vitro assays were predictive
of whole organism responses. Comparisons with work with the same
substances used by Zacharewski indicated that, although there
appear to be many similarities between estrogen receptors in fish
and mammals, androgen receptors are different and also vary between
fish species and tissues. Results from biochemical tests with
various chemicals and pulp mill effluent agreed with short-term
whole fish bioassay data, although some responses were caused
by different modes of toxic action. A new assay developed as a
part of the project demonstrated a mechanism of action for the
effects on fish ovaries that may be a cause of reproductive effects
observed in fish living near pulp mill effluents. This work cautions
against simple extrapolation between species and tests when considering
data from reproductive hormone testing.
This project, coordinated with the project of Dr. Zacharewski,
has improved understanding of endocrine disruption in fish and
mammals by studying a number of natural substances, environmental
pollutants, pharmaceuticals, and industrial chemicals, some of
which are chlorinated. For effects associated with reproductive
hormones it was concluded that caution must be exercised when
extrapolating between biochemical tests and whole organisms and
between different types of organisms.
List
of Reports and Publications
4. Assessing Environmental Risks Associated with Halogenated
Aromatic Hydrocarbons. (95-02)
Dr. C. Metcalfe of Trent University and associates developed a
chemical-specific risk assessment methodology. A number of chemicals
were used to illustrate the large variations in environmental
risk posed by related compounds. (Completed)
A human risk assessment methodology was used to assess consumption
of sport fish from Lake Ontario contaminated with some chlorinated
dioxins, furans, and PCBs. A food chain model calibrated in the
method was in good agreement with observed data from fish and
invertebrate food organisms from Lake Ontario. Toxicity equivalency
factor (TEF)-based exposure estimates derived using various fish
consumption patterns and a Monte-Carlo exposure distribution methodology
were compared to daily intake guidelines for TCDD (which vary
by a factor of about 1500) from agencies in North American and
Europe. For the most restrictive (U.S. EPA) essentially all Lake
Ontario anglers exceeded the recommended intake level. For Health
Canada's recommended tolerable daily intake virtually all anglers
(97.3% or greater depending on the scenario) were below the recommended
limit. The bulk of the difference in estimated risk from these
chemicals is associated with differences in regulatory guidelines
in various jurisdictions. (Completed)
This project validated a food chain bioaccumulation model for
sport fish and provided perspective on the possible human risks
of consumption of Lake Ontario fish contaminated with some organochlorines.
Based on Health Canada's recommendations it was estimated that
risks to anglers from eating Lake Ontario fish containing dioxins
and dioxin-like chemicals are minimal. Differences in recommended
daily dioxin intake values between various jurisdictions produced
substantially different estimates of potential risk.
List
of Reports and Publications
5. PCB Metabolites in Human Plasma and Milk. (95-04)
Dr. R.J. Norstrom and associates of Carleton University worked
on identifying structures and developing a chemical analysis protocol
for determining PCB metabolites in human blood plasma and milk.
(Completed)
Development of existing and new methods for analysis of PCBs
and PCB metabolites (hydroxy‑PCBs) in whole blood and plasma
were carried out. Initial tests were carried out on polar bear,
eagle, and human blood and human plasma. A new chlorinated styrene
compound, presumed to be a metabolite of octachlorostyrene, was
identified in polar bear plasma and detected at very low levels
in human plasma. Evaluation of human cord blood samples from Quebec
found that pentachlorophenol was the main chlorinated phenolic
and that total hydroxylated PCB concentrations were highest in
samples from the lower north shore of the St. Lawrence River followed
by Nunavik and Quebec City. Total hydroxy‑PCBs in whole
blood from Inuit were variable but higher than a pooled blood
sample from southern Quebec and exhibited a significant correlation
with age. Extension of the methods to analysis of milk proved
to be beyond the resources available for the project.
This research both enhanced existing methodology and produced
a new methodology for PCB and hydroxy-PCB measurement in blood
and plasma. These new methods allowed the detection of a new organochlorine
metabolite and provided new information on the distribution of
chlorinated phenolics and PCB metabolites in humans in different
areas of Quebec.
List
of Reports and Publications
6. Synthesis and Aquatic Toxicology of Individual Chlorinated
Alkanes from Different Origins.(95-05)
Dr. D. Muir and associates of the University of Manitoba conducted
biological investigations, using fish, to determine the bioaccumulation
and toxicity characteristics of several types of chlorinated compounds.
(Completed)
Synthesis and purification of amounts of six polychlorinated
alkanes (PCA) sufficient for fish testing, along with three radio-labelled
PCAs for use as tracers were carried out. New, detailed information
for several polychlorinated alkanes (also known as chlorinated
paraffins) was generated for uptake and elimination kinetics and
acute, chronic, and life-cycle reproduction toxicity for freshwater
fish. Half-lives tended to increase with increasing Kow and chain
length, with some influence from the position of the chlorines
on the alkane chain. Short- and long-term growth and survival
testing with rainbow trout noted some behavioural responses and
some liver effects in high doses of some isomers. Short and medium
chain PCAs act on fish via a narcotic mode of toxic action and
high exposure levels, well beyond those expected in the environment,
are required for effects to occur.
This research produced new data concerning fish bioaccumulation
and toxicity of these industrially important organochlorines which
is now available for use in regulatory risk assessment. It has
been used by Environment Canada for Canadian Environmental Protection
Act evaluations.
List
of Reports and Publications
7. Relative Teratogenicity of Environmentally Prevalent Toxaphene
Congeners. (95-07)
Dr. J. Zhu of JP Ztech Company and Dr. L. Chan of McGill University
examined the family of chlorinated compounds known as toxaphene
(also known as chlorobornanes or chlorocamphenes) to determine
the major compounds present in traditional foods of the Canadian
Arctic. These compounds were tested to assist in evaluation of
possible health effects. (Completed)
The relative teratogenicity of technical toxaphene (a complex
mixture) and selected toxaphene congeners (T2 and T12) has been
examined using a rat embryo culture methodology. Based on the
effects on growth, the hearing system, and limb and flexion abnormalities
at various dose levels, the teratogenic toxicity of technical
chlordane cannot be predicted from the toxicity of the congeners
examined. This suggests that the target sites and type of toxicity
is highly congener specific. A physiologically-based pharmacokinetic
model of toxaphene distribution was also prepared. Much of the
existing toxicity information is based on the technical mixture
and this may not be relevant for risk assessments of this banned
organochlorine pesticide.
The results of this study provided improved knowledge about the
toxicity to mammals of these organochlorines which is now available
for regulatory toxicology assessments. The results indicate that
there are serious limitations to the use of existing toxicity
information in risk assessments for toxaphene. As a result the
European Community has funded projects to study the toxicity of
individual toxaphene congeners.
List
of Reports and Publications
8. An Investigation of the Occurrence, Distribution and Biogenic
Origin of Chlorinated Organic Compounds, Including Polychlorinated
Dioxins and Furans, in Peat Bogs.(95-08)
Dr. P.J. Silk of the Research and Productivity Council of New
Brunswick examined the occurrence and sources (natural and man-made)
of several chlorinated substances in peatlands in Maritime Canada.
(Completed)
Peat bogs in six New Brunswick locations were sampled. PCDD/PCDF
isomer profiles, as well as levels of certain other organochlorines
(e.g., chloroform, chloroacetic acids, chloroanisoles, chlorophenols,
chlorobenzoic acids) were determined. Two PCDD and one PCDF isomers
predominate, although none are 2,3,7,8 substituted. This study
suggests a natural, biosynthetic origin for some of the PCDD/PCDFs
found in peat bogs. As well, natural production of some of the
other reported organochlorines by metabolic/degradative processes
of bog-dwelling fungi also appears likely.
This research provides further evidence that organochlorines,
including chlorinated dioxins and furans, are naturally occurring
chemicals and that a number of organochlorines are produced by
living organisms.
List
of Reports and Publications
9. Canadian Emissions Information for Chlorinated Organic
Chemicals. (95-09)
The Canadian Global Emissions Interpretation Centre, a joint initiative
of ORTECH and Environment Canada, has completed a project reviewing
specific literature summarizing atmospheric emission sources of
various chlorinated compounds in North America. (Completed)
The report indicates the general status of available atmospheric
organochlorine emissions information and specific emissions data
for North America summarized from available inventory compilations.
Emphasis was directed towards materials that are being considered
in various industry and government control initiatives, as well
as those specific types of use/source categories which might contribute
to emissions. Chlorinated organic compound emission inventories
in North America are still in the developmental stages, both for
defining priorities and developing the inventories. Although emissions
of some compounds from the chemical production sector are better
characterized, other sources are poorly known. Knowledge gaps
of source strengths for many of the compounds limits several potential
uses of related inventory data and indicate a need to improve
data collection.
The study concluded that improvements in data collection for
atmospheric emissions oforganochlorines are required to facilitate
management initiatives.
List
of Reports and Publications
10.* Research Chair in Risk Communication and Public Policy
at the University of Calgary. (95-11)
This jointly funded (industry, government, and university) chair
has been established to study a wide range of health and environmental
issues, to evaluate the issues from the prospective of both experts
and the general public, and to recommendation improvements in
the risk communication process in order to facilitate efficient
and effective public decision making.
Dr. W. Leiss assumed the chair entitled "The management
and communication of risks as a public policy issue" at the
University of Calgary in January, 1999. In the first 36 months
a numerous tasks have been accomplished. A number of articles
and book chapters have been published and more are in various
stages of development. A new book "In the Chamber of Risks"
was published in 2001. Dr. Leiss also participated in numerous
presentations (39 in 1999, 69 in 2000, 16 in 2001) at invited
lectures, conferences, and short courses, plus he developed and
gave several graduate level seminars and continues to develop
more case studies in risk issue management. As well, a new climate
change risk communication project, using the "EM‑Com",
endocrine modulator risk communication project (www.emcom.ca)
as a prototype, is being developed. Dr. Leiss is one of the principal
agents in the ongoing development of two new risk centres: the
Risk Studies center in the Faculty of Management, University of
Calgary and the McLaughlin Center for Population Health Risk Assessment,
University of Ottawa.
List
of Reports and Publications
11. Assessing the Risks of Chlorine-based Compounds at the
Population-level Using Individual-based Modelling Approaches.(95-13)
Dr. M. Power of the University of Manitoba (University of Waterloo
as of 1999) used fisheries population modelling to further develop
probabilistic risk assessment techniques for selected organochlorines,
focusing on multiple stressor interactions and natural population
compensation mechanisms. (Completed).
A population dynamics field study with brook trout was combined
with lab toxicology results for toxaphene and a fishing exploitation
model to study this issue. The major finding is that summing the
effect of individual stressors results in underestimation of combined
stressor effects, especially at higher levels of stressor intensity.
Both stressor interactions and population regulation mechanisms
must be known to accurately estimate population level effects
of multiple stressors. Additional research reported substantial
declines in a number of organic chemicals, including some organochlorines
and pesticides, in the Thames Estuary in England, but this data
set was not suitable for population effect modelling. A contribution
on combining the use of risk and economics information in risk
management decision-making was also prepared.
This work indicates that a common model for addressing the effects
of populations level stresses, whether caused by organochlorines
and/or other chemical or physical factors, is viable. It cautions
that the effects of multiple stressors on fish populations are
function of intensity of the stressors andare not accurately predicted
by simple addition of individual stressor effects.
List
of Reports and Publications
12. Probabilistic Assessment of Risks to Infants from Consuming
Breast Milk Containing Organochlorines. (95-16)
S. Hoover and associates of Golder Associates Ltd (moved to the
California EPA in 1999) analyzed available Canadian data on organochlorines
in human breast milk to evaluate possible health effects. (Completed)
Available literature information on the topic was reviewed and
evaluated. Probability distribution representing the organochlorine
content of human milk and milk consumption were used to derive
estimates of exposure to infants. Qualitative and quantitative
analyses of risks were carried out for carcinogenic and noncarcinogenic
chemicals using guidelines and/or protocols from several agencies.
Current levels of most persistent chlorinated contaminants monitored
in breast milk do not appear to pose health concerns. This conservative
screening level assessment indicated possible risks for PCBs and
dioxins/furans based on findings in epidemiological studies, comparisons
of exposures with guidelines, and calculations of theoretical
cancer risks. However, the benefits of breast‑feeding clearly
outweigh potential health concerns associated with exposure to
PCBs and dioxins/furans.
This study concluded that most chlorinated compounds measured
in Canadian breast milk do not pose significant health risks to
infants. In addition, it provided appropriate context for the
potential concerns associated with PCBs and dioxins/furans, reaffirming
the choice of breast milk as the preferred infant food.
List
of Reports and Publications
13. The Environment and Its Impact on Children's Health -
An Initiative for Action. (95-17)
Dr. D. Avard (Successor as Executive Director is D. Walker as
of January 1998) and associates of the Canadian Institute of Child
Health have carried out a national study on the impact of the
environment on children's health. Chemicals in the environment,
including organochlorines, represent one of the many areas of
concern that were evaluated. (Completed)
A multistakeholder national advisory committee provided initial
direction. A National Outreach survey of activities by various
groups was carried out. "What On Earth?" a National
Symposium on Environmental Contaminants and the Implications for
Child Health was held in Ottawa in 1997. Key papers appeared as
a Supplement to the Canadian Journal of Public Health. Ten bilingual
information sheets on selected environmental topics were distributed
as the Environmental Hazards: Protecting Children series. In 1998
CICH co-sponsored a conference "The Air Children Breathe:
The Effects on Their Health" where the science and policy
aspects of children's health were examined. The second draft "Environmental
Contaminants and the Implication for Child Health" was released
in 1999 and the third edition of "The Health of Canada's
Children" was released in 2000.
CICH provided research reviews, policy options, and public discussion
forums for various environmental issues related to children's
health. CICH continues to provide data and analysis of the overall
status and trends in children's health in Canada. This provides
a basis for evaluation of the significance of environmental matters
relative to other well-known influencing factors such as nutrition,
social and economic factors, and accidental deaths, as well as
providing perspective on the relative importance of various issues
within the environmental area.
List
of Reports and Publications
14. Sources and Ocean to Atmosphere Fluxes of Selected Volatile
Organochlorine Compounds. (95-18)
Drs. R.M. Moore and R.L. White of Dalhousie University studied
sources and estimated amounts of selected organochlorine compounds
produced by natural oceanic processes that may contribute to atmospheric
loading of chlorinated substances. (Completed)
Concentration measurements of low molecular weight organochlorine
compounds in various locations in the Atlantic Ocean were made,
with the objective of determining which compounds have an ocean
source and estimating ocean to atmosphere fluxes. Data indicated
that trichloroethylene (TCE) and tetrachloroethylene (PCE) are
supersaturated in tropical and temperate waters and are emitted
to the atmosphere. TCE, PCE, and dichloromethane appear to be
primarily derived from atmospheric sources and appear to enter
ocean surfaces waters in high northern latitudes in winter and
are carried southwards in deeper water. Persistence of these chemicals
in ocean waters may be longer than atmospheric persistence and,
if so, lifetimes may be of the order of decades. Laboratory experiments
have not found any detectable production of tri- and tetrachloroethylene
by a species of red alga (Porphyridium purpureum) which
has been reported to be a producer. This organism was found to
produce significant amounts of chloroform and to possess a thermally
labile, heme‑containing peroxidase enzyme.
This project has increased our knowledge of the relative magnitudes
of the natural and anthropogenic sources of a number of volatile
organochlorines and of their global movements and fate.
List
of Reports and Publications
15. An Environmental Issue Audit Methodology for Chlorine
Industry Managers. (95-20)
R. Willis and Dr. T. Vigerstad of Dalhousie University evaluated
printed and electronic press information and assessed the potential
for controversy in emerging environmental or human health issues.
The environmental estrogen issue was used as an example in facilitating
risk communication to risk managers. (Completed)
Three components (Issue Literacy, Strategic Scientific Analysis,
and Content Analysis) were determined to be essential to the objectives
of tracking, improving understanding, making predictions, and
enacting strategic management decisions with respect to an environmental
issue. Strategic Scientific Analysis of the environmental estrogen
literature published before 1990, indicated that the key issues
that would attract professional and public attention in the 1990's
would be organochlorines and sperm counts, testicular cancer,
breast cancer and learning and behavioral effects on children.
Content Analysis showed Canadian media treated the issue between
1990 and 1996 as a policy issue with IJC and Greenpeace as dominant
information sources. However, media in the USA treated it as a
science and regulation issue with EPA and NCI being the dominant
sources.
The study indicated that systematic evaluation of print and electronic
media can assist in predicting emerging environmental or health
controversies and in directing subsequent risk communication and
risk management actions.
List
of Reports and Publications
16. Assessing the Influence of Elevation and Temperature on
the Deposition of Persistent Pollutants in Alberta and British
Columbia. (96-02)
Drs. D.W. Schindler of the University of Alberta and J. Blais,
now at the University of Ottawa, examined the applicability of
elevation-dependent enhanced precipitation and the cold condensation
hypothesis to explain regional movements and fate of persistent
organochlorines. (Completed)
Concentrations of several organochlorines in snow samples were
observed to rise with increasing elevation in mountains in Alberta
and British Columbia. These data support the contention that temperature-dependent
condensation of low volatility persistent organic chemicals is
occurring in alpine areas by a process similar to the tropical
to polar process observed on a world scale. This provides an explanation
for elevated levels reported in some remote alpine lake systems.
This study improved the knowledge of the environmental fate and
transport of persistent organic chemicals and demonstrated that
transport by temperature-dependent condensation appears to be
occurring in mountainous areas in a manner similar to that reported
for global scale movements.
List
of Reports and Publications
17. Developing a Synoptic View of Long Term Trends in Organochlorine
Levels in the Great Lakes Ecosystem. (97-01)
Dr. D. Mackay and associates of the Canadian Environmental Modelling
Centre at Trent University analyzed multimedia monitoring data
for persistent organochlorines. The objective was identification
and interpretation of long-term trends, including establishment
of ecosystem half-lives. Data were consolidated via transformation
to Equilibrium Lipid Partitioning (ELP) concentrations, a novel
concept, which assists in improving interpretation of monitoring
data. (Completed).
Air, water, sediment, fish, and bird monitoring data for PCBs
in the Great Lakes area were collected from various sources and
converted a common concentration unit of g/m3. The
composition of the various media samples were usedto convert the
data to ELP units. A further adjustment was made by using a factor
equal to the ratio of the mean ELP for the phase in question relative
to the ELP for water to consolidate all data into a common trend
band. Results indicate definite substantial decreases in PCB levels
in Lakes Ontario and Superior since the 1970's with disappearance
half-lives being of the order of 10 years.
This methodology for consolidating diverse multi-media monitoring
data is offered as an improved reporting and assessment approach
for evaluating environmental trends in levels of various organic
chemicals. Applying this method to data for the Great Lakes produces
strong multi-media evidence for large declines in PCB concentrations
over the last 30 years.
List
of Reports and Publications
18.* Reproductive/Developmental Effects of a Biologically
Relevant Mixture of Environmental Pollutants Representative of
Human Body Burdens and Interaction with the Phytoestrogen Genistein
in the Rat. (97-02)
Dr. W. Foster and associates of McMaster University evaluated
reproductive and endocrine physiology in male and female offspring
after maternal and lactational exposure to a mixture containing
various organochlorines (including some PCBs, TCDD and polychlorinated
benzenes), organochlorine pesticides (including DDT metabolites,
dieldrin, methoxychlor, mirex), and metals (including lead and
cadmium). Exposed adult male rats were also examined. The natural
phytoestrogen genistein was studied as a possible influencing
factor. (Completed)
Pregnant female rats were exposed to a mixture containing various
chemicals each at 1X, 10X, 100X its minimum risk level (MRL) concentration
and they and their offspring were examined. No changes were found
for pregnancy weight gain, litter size, or sex ratio. For offspring
there were no differences between exposure groups for most tests.
However, females exhibited an earlier onset of puberty while male
exhibited a transient increase in prostate weight. Thyroxin levels
were unaffected except for a transient change at the 1X and 10X
doses in male pups. Adult male rats were exposed at 1X, 10X, 100X
and 1000X mixtures as above. No effects were found on weight or
growth. Reproductive organs and sperm production and function
were not affected. Some minor changes in circulating thyroxin
(T4, T3, TSH) were found at some doses, but no significant reproductive
effects were found.
The results suggest that exposure to low doses of a complex mixture
of chemical pollutants can cause modest changes in a few parameters
in the offspring of exposed female rats and in exposed adult male
rats. Determination of the biological significance of observed
changes is being carried out and will be reported in peer-reviewed
publications.
List
of Reports and Publications
19.* Inactivation of Cryptosporidium parvum and microbial
indicators by ClO2: a natural water and pilot-scale
approach. (97-03)
Dr. C. Chauret of Indiana University and Dr. R.C. Andrews of the
University of Toronto worked on improving drinking water disinfection.
Chlorine dioxide treatment was examined to determine efficacy
against the difficult to treat protozoan parasite Cryptosporidium.
As Cryptosporidium is difficult to measure, selected microbial
indicators were examined as possible surrogates. (Completed)
Chlorine dioxide inactivation of Cryptosporidium parvum
was investigated using a cell culture method and in vitro
excystation to assess the inactivation kinetics of Cryptosporidium
oocysts. No significant differences were observed in inactivation
between three different natural waters obtained post-filtration
from water municipal water treatment plants and in deionized-distilled
water. However, sand shearing in the bench-scale testing did substantially
increase the susceptibility of oocysts to chlorine dioxide inactivation.
The easily measured microbial indicators, Bacillus subtilis
(aerobic) spores and Clostridium sporogenes (anaerobic)
spores, were found to be more sensitive, by a factor up to ten
times, to chlorine dioxide inactivation than C. parvum oocysts,
and were judged to be inadequate surrogate indicators for C.
parvum inactivation. It was also noted that C. parvum
oocysts from two different suppliers were markedly different in
their resistance to chlorine dioxide inactivation.
The results are a substantial contribution to ongoing research
to better understand and reduce the adverse human health impacts
of Cryptosporidium parvum in treated drinking water. The
concentration-time inactivation results add valuable data to the
limited knowledge base on chlorine dioxide inactivation of C.
parvum oocysts while the results from the microbial surrogate
studies indicate that a promising microbial surrogate method is
unsatisfactory and that alternative microbial approaches or improved
C. parvum measurement methodologies are needed.
List
of Reports and Publications
20. *Oxidative Stress as a General Mechanism Underlying Species
Sensitivity to AH Receptor Agonists: Implications to the TEF Concept
and Wildlife Risk Assessment. (97-04)
Drs. S. Kennedy and T. Moon of the University of Ottawa studied
oxidative stress as a possible mode of action for dioxin-like
toxicity. Species of differing sensitivity were studied. Both
cell-culture methods and direct injection into bird eggs were
used and both chlorinated and nonchlorinated chemicals were tested
in this examination of aspects of the dioxin toxicity equivalent
factor (TEF) approach.
Chicken and duck egg injection was used to estimate PCB 126 effects
and the influence of antioxidants on several toxic endpoints.
Results suggest that adipose tissue is a target. Biochemical pathways
involving lipid management are important for dioxin-like PCB 126
toxicity and oxidative stress does appear to play a role in PCB
126 toxicity. Ducks are less sensitive, likely due to higher basal
levels of the antioxidant enzyme glutathione peroxidase in the
liver. At PCB 126 levels causing lipid peroxidation and cytochrome
P4501A induction in chicken liver cells there was no effect on
the number of beta-adrenergic receptors. However, an increase
in the binding constant suggested a change in cell membrane fluidity
and peroxidation which may impact hormone-induced metabolic and
physiological changes during exposure to chemicals with dioxin-like
toxicity. Induction of apoptosis (programmed cell death) was not
observed in cultured embryonic chicken heart cells, suggesting
that the apoptosis observed in intact embryos is likely an indirect
effect induced by another biochemical mechanism.
The results of this research provide some biochemical details
of dioxin-like toxicity in developing birds. Specifically, the
research has expanded knowledge on the role of oxidative stress
in the toxicity of TCDD and PCBs in birds. The results suggest
that differences in antioxidant defence mechanisms, such as enhanced
metabolic degradation may explain differences in bird species
sensitivity. This work enables future research directed toward
determining if oxidative stress can be used to estimate species‑relevent
TEFs.
List
of Reports and Publications
21. * Multimedia Fate and Toxicological Effects of Chlorinated
Compounds in Urban Areas. (97-08)
Dr. M. Diamond of the University of Toronto and associates studied
some semi-volatile organic compounds, including chlorinated organics
(hexachlorobenzene, chlorinated paraffins, chlordane and PCBs)
and nonchlorinated organics (PAHs), with differing fate and toxicity
characteristics. The fate of these chemicals in urban and rural
environments and measures of toxic potency of the complex mixture
of compounds found in urban areas (effects on zebrafish embryo
development and aryl hydrocarbon receptor binding in cell cultures)
were examined. (Completed)
Sampling of air, soil, vegetation, water, sediment, and organic
film on windows was carried out along an urban‑rural gradient
in Southern Ontario. Analysis for a suite of organic chemicals
was carried completed and a multimedia urban model (MUM) was developed
and calibrated with the field data. Notable observations were
that these chemicals are more mobile in urban areas due to the
large amount of impervious surfaces, the highest concentrations
were on impervious surfaces, and total concentrations decreased
along an urban‑rural gradient. Toxicological studies of
the complex mixtures obtained from urban organic films indicated
that the chemicals acted in an antagonistic manner and the relative
potency decreased from the nonpolar aromatic fraction (includes
high molecular weight PCBs and PAHs), through the polar aromatic
fraction (includes aliphatic acids, alcohols, and nitro‑PAHs),
to the nonpolar aliphatic fraction (includes polychlorinated alkanes,
low molecular weight PCBs and hexachlorobenzene).
This research generated new information on the fate of various
semi‑volatile compounds which was incorporated into a multimedia
fate model for urban environments. Both the data and the model
will be useful for improving understanding of fate processes and
estimating human and environmental exposures for risk assessments.
The toxicity information collected provides valuable insights
into the interactions and relative hazards of the complex mixtures
of organic chemicals found on various surfaces in urban environments.
List
of Reports and Publications
22. * The Role of Fungal Metabolism in the Genesis of Chloroorganics
in Peat: Mechanisms of Formation and Environmental Fate. (97-09)
Dr. P. Silk and associates of the Research and Productivity Council
(RPC) of New Brunswick discovered a unique isomer pattern dominated
by 1,3,6,8 and 1,3,7,9-TCDD and 2,4,6,8-TCDF in bogs. This may
be produced by fungal enzymes and 2,4-dichlorophenol. Breakdown
and synthesis of various organochlorines by bog fungi was studied
and chemical types and production levels estimated. Plant and
animal samples from bogs were analyzed to determine accumulation
of chlorinated fungal metabolites. (Completed)
This research confirms that fungi play a major role in the production
of natural chloroaromatics found in peat and other terrestrial
ecosystems. In particular the white and brown rot fungi (Basidiomycetes)
are prolific producers of AOX, chlorohumus, and chloroaromatics.
Experimental evidence indicates that fungally mediated chlorination
using chloride ion (Cl-) is part of the biosynthetic
machinery essential to fungal activity. The presence and interaction
of certain enzymes and chlorinated metabolites strongly suggests
that there is native potential to produce chlorinated dioxins
and furans from naturally produced organochlorines.
This research provides mechanistic details of how a number of
organochlorines are naturally produced by common fungi and provides
an explanation of why many chlorinated organic chemicals which
can be commonly found in peat bogs and other terrestrial ecosystems
may be the source of natural production of some chlorinated dioxins
and furans.
List
of Reports and Publications
23. * Source Identification of Chloroacetic Acids (CAA) in
the Environment by GC/C/IRMS. (97-10)
Dr. S. Mabury of the University of Toronto and associates developed
a compound-specific carbon isotope analysis based on C13/C12
ratios which allows differentiation between natural and anthropogenic
sources of chloroacetic acids. This analytical technique enables
more detailed research on the processes and fate of chloroacetic
acids to be carried out. Chloroacetic acids may cause adverse
effects on plants, but there is uncertainty about the sources
of levels observed in the field. (Completed)
Laboratory tests indicated that various reagent grade chloroacetic
acids produced distinct isotopic signatures. This suggests differences
in source carbon and/or production methods and represents a new
method for characterizing source contributions in environmental
samples. Aquatic fate and persistence studies on these chemicals
indicated varying persistence: 14, 4, and 40 days for mono-, di-,
and trichloroacetic acids, respectively. Dichloroacetic acid appears
to be biotransformed by microbes, unlike the others. Current use
chloroacetanlide herbicides, such as metalochlor, produce substantial
amounts of monochloroacetic acid via photodegradation. As well,
deposition of chloroacetic acids from atmospheric particulates
represents a substantial, newly found source of chloroacetic acids
in the aquatic environment.
This work enhanced analytical methodology by providing a means
to identify the sources of chloroacetic acids by their stable
carbon isotope ratio. It also generated new aquatic fate, persistence,
and source information for these chemicals which will be valuable
in environmental risk assessments and regulation development.
List
of Reports and Publications
24. The Use of Multimedia Models in the Screening for POPs.
(98-02)
Dr. F. Wania of Wania Environmental Chemists Corp. and Dr. D.
Mackay of Trent University examined various multimedia models
to assist in better defining persistence and long range transport
potential for organic chemicals. This was a multistakeholder effort
with support from C4, CCC, and Eurochlor and was co-ordinated
with European and American investigators who provided their own
support. This work has been offered to the United Nations Environmental
Program (UNEP) Criteria Working Group and others for use in programs
screening candidate chemicals for new lists of persistent organic
chemicals (POPs) when suitable monitoring data are unavailable.
(Completed)
Chemical property profiles for 26 chemicals were selected and
used in a number of models (12 for persistence and 8 for long-range
transport) to calculate persistence and estimate long-range transport
potential. Since absolute values for overall persistence and long-range
transport potential differ substantially among models, these characteristics
can not be defined independently of the model used to generate
the estimate. However, all persistence models based on Level III
multimedia calculations which include a sediment compartment and
all long-range transport potential models produced similar relative
persistence and long-range transport potential rankings, respectively.
The use of specific chemicals as benchmarks for persistence and
long-range transport appears to be a viable alternative to the
current day or month half-life and atmospheric travel distance
methodologies which dramatically reduces the influence of model-specific
factors.
This project is a substantial contribution to improving the scientific
basis of chemical classification schemes that depend on reliable
methods for estimating persistence and long-range transport potential
characteristics.
List
of Reports and Publications
25. Bacterial Interactions with Chlorinated Organic Compounds.(98-04)
Drs. H. Lee and J.T. Trevors of the University of Guelph are studying
the metabolic degradation rates of labelled pentachlorophenol
and 2,2',5,5'-tetrachlorobiphenyl by selected strains of soil
bacteria. The objective is to determine if the biodegradation
of these chemicals is limited by uptake into the bacteria. The
influence of modifying factors such as temperature, pH, presence
of other substances, etc. are being examined and exposure-received
dose relationships are being determined. Improved knowledge of
biodegradation will contribute to better understanding of organochlorine
fate and persistence.
PCP appears to be taken up passively with no differences in uptake
between 4°C and 30°C for Sphingomonas sp. UG30. Differences
in uptake between Sphingomonas and E. coli have
been observed. Membrane fluidity in Sphingomonas appears
to decrease with PCP exposure. There is no evidence of energy-dependent
uptake of TeCB into Ralstonia eutropha H850 and the uptake
was not temperature dependent, but TeCB does increase cell membrane
fluidity. A low rate of TeCB accumulation may be the rate-limiting
step in TeCB biodegradation. Work on collecting comparative data
for bacterial species which do not metabolize PCP or TeCB is underway.
List
of Reports and Publications
26. Formation and Evolution of Trihalomethanes and Haloacetic
Acids in Drinking Water Distribution Systems. (98-08)
Drs. M. Rodriguez and J.-B. Sérodes of Laval University are conducting
a study in three municipal water treatment plants in the Quebec
City area. Field and laboratory-scale sampling are being carried
out to characterize the influence of various operational parameters,
as well as the effects of the distribution system, on chlorine
disinfection by-product (DBP) formation and fate. Models, prepared
using collected data, will be used to aid in improving operational
practices to minimize DBP in treated water delivered to consumers.
This study is being co-ordinated with another funded by NSERC
and local municipalities on improving the human DBP exposure information
used in epidemiological studies of municipal water supplies.
A 16-month program began in April 2000 with sampling about 12
to 15 points per utility per month (water treatment works and
distribution system) as well as of simulating chlorination conditions
in laboratory. A preliminary sampling program, based principally
on residual chlorine measurements in about 30 points per utility,
allowed to select the definitive sampling points for the project.
In field and laboratory studies measured water quality parameters
are: THMs, HAAs, free residual chlorine, turbidity, total organic
carbon, UV‑absorbance at difference wave lengths, bromide,
pH and water temperature. Preliminary results indicate that chlorinated
disinfection byproducts are 1.5-3 times higher in the extremities
of the distribution system and from 2-4 times higher the summer
(water temperatures higher than 22°C) in comparison with those
measured at fall‑winter conditions (water temperatures from
2 - 8 °C).
List
of Reports and Publications
27. Anaerobic Biodegradation of Mixtures of Halogenated Organic
Compounds. (98-09)
Drs. B. Sleep and D. Bagley of the University of Toronto are conducting
laboratory and field studies on the microbial degradation of mixtures
of organohalogens (tetrachloroethylene, carbon tetrachloride,
chloroform, ethylene dibromide, and a mixture of chloroflourocarbons)
using bacteria originating from previously contaminated field
sites. In addition to determining biodegradation rates, nutrient
requirements, inhibitory influences, and degradation products,
key degrading bacteria species will be identified by genomic fingerprinting.
Field-scale soil/groundwater fate and transport models will be
developed from experimental data.
Microcosms have been established to study two mixture types:
perchloroethylene and CFC-113 and CFC 114, as well as perchloroethylene
and CFC-11. Results to date indicate that CFC-113 and CFC-11 both
inhibit PCE biodegradation at levels as low as 0.1 mg/L while
CFC 114 is much less inhibitory. Dominant members of the laboratory
microbial consortium and an existing computer model has been modified
to simulate PCE degradation. Further model development and refinement
and testing of a microbial community from a contaminated field
site are to be carried out.
List
of Reports and Publications
28. Exposure to Chlorination By-Products During Pregnancy
and Stillbirths. (99-01)
Drs. L. Dodds of Dalhousie University and W. King of Queens's
University are conducting an epidemiological study funded by the
Toxic Substances Research Initiative from Health Canada and Environment
Canada. This case‑control study examines the relationship
between exposure to chlorination by‑products during pregnancy
and stillbirths. The TSRI grant focuses on THMs in water supplies.
C4 is enhancing this study by supporting the collection and analysis
of haloacetic acids (HAA) and lead in all collected water samples.
As data sets with simultaneously measured levels for both THM
and HAA are rare, this project is an efficient way of obtaining
important human exposure information on disinfection by‑products.
Simultaneous analysis of exposure to the major by‑product
groups has the potential to be very informative with respect to
identifying the specific by‑products affecting health outcomes.
The collected data will be of use both for the epidemiological
portion of this study and in improving the knowledge base for
human exposure to chlorine‑based water disinfection by‑products.
Methods for measurement of THMs and HAAs were subjected to interlaboratory
testing and the effects of travel time, preservative and outdoor
air temperature on THM and HAA values were assessed and collection
methods modified accordingly. Subject recruitment, interviews
and water sampling are well under way for both Nova Scotia and
Eastern Ontario. Water tests as of November, 2000 (n=80) for subjects
living in areas served by a municipal water supply indicated a
median total THM value of 57 μg/L and the median total HAA
value of 35 μg/L. Generally, Nova Scotia samples demonstrated
greater variability in measurements and higher median values.
A re‑analysis of previous data revealed an association between
stillbirths due to abruptio placenta and trihalomethane level
and the current study has been expanded to include cases of abruptio
placenta among live births in addition to stillbirth cases and
controls. Relative risk analyses will be performed at the completion
of subject recruitment and data collection which is scheduled
for Spring 2002.
List
of Reports and Publications
29. Photochemistry of Short-Chain Chlorinated Paraffins.
(99-02)
Drs. K. Friesen and A. Abd-El-Aziz of the University of Winnipeg
and Dr. G. Stern of the Freshwater Institute are examining the
persistence of certain isomers and selected mixtures of polychlorinated
n-alkanes in purified and natural waters. These compounds have
been used as fire retardant additives in a variety of industrial
products and have been detected in waste-water effluents and aquatic
animals. New information on degradation by sunlight and possible
enhancement of photodegradation in the presence of catalysts,
will provide important basic information on fate/persistence and
possible remediation chemistry, which may be used in the regulatory
process for these chemicals.
With the additional support of the CPIA the project has been
modified to investigate the hydrolytic stability of a series of
PCA isomers. So far the environmental persistence, both hydrolytic
and photolytic, of individual PCA isomers (C10, C11 and C12),
as well as work on the photocatalytic degradation of the individual
isomers using both heterogeneous (TiO2) and homogeneous (H2O2)
methods has been carried out. Work on several SCCP mixtures is
continuing. These results provide new information on the environmental
aquatic persistence of PCAs as well as the potential of several
photocatalysts to degrade them.
List
of Reports and Publications
30. * Synthesis and Toxicology of Halogenated Dimethyl Bipyrroles.
(99-03)
Dr. R.J. Norstrom and S.A. Tittlemier of Carleton University worked
on synthesis, purification, and chemical characterization of selected
isomers of a naturally-occurring, bioaccumulating halogenated
organic chemical group called halogenated dimethyl bipyrroles
(HDBP). These chemicals, which contain both chlorine and bromine,
were found at high levels (up to 140 ppb wet weight in eggs and
up to 550 ppb in liver) in some marine birds in Canada and are
thought to be produced by marine bacteria (Tittlemier et al.,
1999. Environ Sci Technol 33:26‑33). As this chemical group
has some structural similarities with PCBs and chlorinated dioxins,
data obtained provides some perspective on bioaccumulation and
hazard/toxicity in natural versus manufactured chlorinated organics.
Four HDBP congeners were synthesized, characterized and used
as standards in a subsequent analytical work. In a global monitoring
study of marine mammals the highest levels were from the northern
Pacific Ocean, suggesting a source may occur in this area. Concentrations
ranged from 2,888 ng/g lipid weight in Dall's porpoise samples
from the northwestern Pacific Ocean to 8 ng/g lipid weight in
seals from Lake Baikal. A marine food web study found increases
with increased trophic level at a rate of about 10 time per trophic
level, similar to some PCBs, except for ringed seals which may
have the capability of metabolizing HDBPs. This is the first report
of natural organohalogens accumulating in food webs. Although
able to produce some dioxin-like activity in an in vitro
bioassay (cytochrome P450 1a induction) with a potency similar
to PCBs with one chlorine in the ortho position, no negative effects
were found in tests with birds (American kestrel reproduction),
fish (Japanese medaka) embryos, and amphibians (Xenopus
tail resorption bioassay) and they did not exhibit estrogenic
activity in a chicken embryo hepatocyte bioassay.
The work is the first detailed evaluation of complex chlorinated
and/or brominated organic chemicals which are widely distributed
throughout the world and, based a variety of evidence including
similarity to an known marine bacterium natural product, appears
to be of natural, non-anthropogenic origin. Despite having physical-chemical
properties and environmental fate characteristics similar to
some chlorinated chemicals of anthropogenic origin such as PCBs,
and exhibiting some dioxin-like activity in standard biochemical
screening tests, they did not exhibit adverse effects when tested
using various whole organism toxicity tests. These results confirm
that some complex, bioaccumulating organohalogens distributed
throughout ecosystems of the world are produced by living organisms
via natural processes and that the presence of chlorine or other
halogens in a chemical does not automatically cause it be particularly
potent or have unique toxicity characteristics.
List
of Reports and Publications
31. * Direct Measurement of Total Organic Chloramines. (00-02)
Dr. S. Andrews of the University of Waterloo is examining size
exclusion high performance liquid chromatography with post-column
reaction and electrochemical detection as a means of measuring
organic chloramine concentrations in drinking water, surface waters,
groundwater, seawater and municipal wastewater. A method for the
direct determination of organic chloramines is in demand as most
conventional analytical methods cannot be used to differentiate
between inorganic chloramines and organic chloramines. A rugged
and reliable method for the analysis of organic chloramine in
the above aqueous samples that can be used in disinfection monitoring
and/or toxicity testing is expected.
Initial testing with purified laboratory water and tap water
have demonstrated that the organic chloramines can be separated
from inorganic chloramines and free chlorine using size exclusion
columns. Development work continues on improving separation,
and thereby method sensitivity, with tests on different types
of exclusion columns and examining means of reducing column reactivity
to chlorine species.
List
of Reports and Publications
32. Sources and Fate of Semi-volatile Organic Compounds in
Urban and Surrounding Areas. (00-03)
Drs. M. Diamond, G. Stern, and B. McCarry (University of Toronto,
Freshwater Institute, and McMaster University, respectively) are
continuing work on improving the qualitative and quantitative
understanding of the fate of various organic chemicals in urban
areas using a variety of chlorinated and nonchlorinated compounds
as chemical tracers. This project builds on a previous C4 project
and aims to provide data and models for better estimating exposures
for regulatory decision-making. Project objectives include continued
documentation of multimedia concentrations of various SOCs, further
development and calibration of the multimedia urban model, and
estimation of total emissions for various SOCs for the Toronto
region.
List
of Reports and Publications
33. The Potential of Anthropogenic Naturally-Produced Organohalogens
to Biotoxify in the Environment. (00-05)
Drs. P. Silk and J. Macaulay (Research and Productivity Council
of New Brunswick are building on previous C4 projects (95-08,
97-09) to study the biochemical details of production of various
chlorophenols, chlorocresols, chloromethoxyphenols, and chlorinated
dioxins and furans, both in vitro and in vivo, from
natural and anthropogenic precursors. In addition to white rot
fungus, which has previously been shown to naturally produce chlorinated
dioxin and furan precursors, these researchers have found that
baker's yeast can produce small quantities of chlorophenols and
the significance of this pathway will also be examined. The work
will contribute to the growing information on the natural production
of chlorinated organics, particularly chlorinated dioxins and
furans, and may assist in explaining the observation that PCDD/F
can be formed in living mammals via an enzyme-catalyzed coupling
of certain chlorophenols.
List
of Reports and Publications
34. Bioaccumulation and Biochemical Effects of Halogenated
Phenolic Compounds in Fish. (00-06)
Drs. A. Fisk, S. Brown, and N. Neumann (University of Guelph)
are studying the dietary accumulation and biochemical effects
of hydroxylated PCBs and pentachlorophenol in trout. Assimilation
efficiency, half-life, biomagnification factors, biotransformation
rates, and tissue distribution will be determined and QSARs for
estimating parameters for untested compounds will be prepared.
Also, the ability of fish to metabolize PCBs to OH-PCBs will be
assessed. In addition, thyroid and immune system effects in fish
from environmentally relevant halogenated phenolics at environmentally
realistic exposure levels will be investigated.
List
of Reports and Publications
35. Biotransformation and Biochemical Responses of Chiral
Organohalogen Compounds in the Aquatic Environment. (00-07)
D. Muir, C. Wong, P. Hoekstra, and S. Mabury (University of Guelph
and University of Toronto) are investigating the influence of
bioaccumulation and biotransformation of chiral (asymmetric, optically
active forms of the same compound that are structural mirror images)
organohalogens on environmental fate and distribution. Chiral
forms of the same compound can be taken up and metabolically degraded
differentially and can exhibit dissimilar toxic potencies. The
objectives are: assessment of selective biotransformation in fish
and marine mammal cell cultures, assessment of chiral accumulation
and biotransformation by fish and invertebrates exposed via the
diet, estimation of chiral accumulation and biotransformation
in the sediment and food web of Lake Ontario, and determination
of the in vitro estrogenic activity of individual o-p'DDT
enantiomers. The knowledge gained will aid in improving risk assessments
for current use and new chiral organohalogens (e.g., polychlorinated
alkanes, some pharmaceuticals e.g, clofibric acid, and various
pesticides such as tefluthrin, permethrin, fenvalerate, alachlor),
as well as improving the understanding of regulatory monitoring
data for legacy chiral organohalogens (e.g., PCBs, DDT, HCH, chlordane,
toxaphene).
