RISKS POSED BY PCBs
Prepared by William Murray
Science and Technology Division
THEIR CHEMICAL STRUCTURE AND INDUSTRIAL USE
HOW THEY BECAME FEARED
BAN AND DESTROY ALL PCBs?
NATIONAL INVENTORY OF PCBs
HAZARDOUS WASTE MANAGEMENT REGULATIONS
RISKS POSED BY PCBs
(PCBs) pose a very much lower health risk than such toxic chemicals as
vinyl chloride, cadmium and cyanide. Everyday, people use chemicals that
are far more toxic and carcinogenic without a second thought. For example,
it is common practice to clean paint brushes or paint-splattered hands
with gasoline, yet gasoline contains a number of chemical compounds, such
as benzene and 1,3-butadiene, that are substantially more dangerous than
PCBs. While PCBs were being commercially manufactured, from the early
1930s to 1980, electrical-equipment workers in American factories were
exposed every day to high concentrations of them. In spite of this long-term
exposure, these workers experienced few adverse health effects. The moderate-to-low
toxicity of PCBs is in sharp contrast to the public perception of them
as extremely toxic and cancer-causing. This high level of public anxiety
has severely hampered the Canadian government's effort to manage waste
THEIR CHEMICAL STRUCTURE AND INDUSTRIAL USE
PCBs are a group of synthetic
chemicals belonging to the family of organic chemicals known as chlorinated
hydrocarbons. They consist of a biphenyl molecule, made up of hydrogen
and carbon, to which chlorine atoms can be attached. Figure 1 shows the
typical molecular structure of a PCB. Chlorine atoms (Cl) can chemically
bond on to any of the other nine hydrogen (H) sites, giving a total of
209 possible chlorine arrangements or isomers.
PCBs are extremely stable,
relatively fire-resistant, and non-corrosive. These characteristics made
them very useful in a wide range of applications, such as hydraulic fluids,
dye solvents and plasticizers.(1)
The major application of PCBs, however, has been in electrical equipment.
In the 1930s, the electrical industry began using PCBs in transformers,
the ballast of fluorescent lights, electromagnets and in other electrical
equipment where a stable, fire-resistant, non-conducting oil was required.(2)
HOW THEY BECAME FEARED
Until approximately 1968,
PCBs were considered to be one of the wonder products of the chemical
industry. The possibility that PCBs might pose a human health risk became
a concern only after two separate incidents, one in Japan and one in Taiwan,
where cooking oil became contaminated by PCBs. The more serious occurrence
was the Japanese Yusho incident, where nearly 1,500 people consumed contaminated
oil, ingesting 0.5 to 2 grams of PCBs per person. Some individuals became
severely ill with such symptoms as eye discharge, systemic gastrointestinal
symptoms with jaundice, edema, abdominal pain and chloracne (a very persistent
form of skin eruption that can last for up to three years).
All the Yusho victims recovered;
however, there were long-term consequences. Pregnant Yusho victims had
shortened gestational periods and gave birth to smaller-than-normal babies
who as children exhibited slight reductions in mental development and
impaired motor skills. A four-year follow-up study indicated that the
development of these children continued to lag behind that of their peers.
A large research effort
focusing on PCB toxicology and carcinogenicity was prompted by this outbreak
of illness. Surprisingly, animal testing failed to demonstrate PCBs to
be a highly toxic class of chemicals. These results were corroborated
by health surveys of electric industry employees. Workers who had spent
30 years in daily physical contact with PCBs showed few if any of the
health problems exhibited by Yusho victims.
PCBs are susceptible to
thermal conversion to polychlorinated dibenzofurans (furans) and polychlorinated
dibenzodioxins (dioxins).(3) Chemical
analysis of the contaminated cooking oil revealed that it contained, in
addition to PCBs, relatively high concentrations of furans and quaterphenyls
and a low concentration of dioxins. It is now hypothesized that the action
of high-temperature frying converted some of the PCBs to furans and dioxins
which, it is believed, caused the Yusho illnesses.(4)
It should also be noted that, even without heating, dioxins and furans
occur as low-level contaminants of PCB oils (less than 2 ppm) as a result
of the normal synthetic process.(5)
Although pure PCBs have been vindicated in the scientific literature,
the belief that PCBs are deadly remains firmly fixed in the public's mind.
There are no documented
cases of human death due to acute PCB exposure. Victims of industrial
PCB accidents report chloracne, eye discharge, swelling of the upper eyelids,
hyperpigmentation of the nails and skin, numbness of limbs, weakness,
muscle spasms and chronic bronchitis. These symptoms, which are similar
to those associated with poisoning by a variety of chlorinated organic
compounds, are believed due to the dioxins and furans that normally contaminate
PCBs.(6) According to Dr. M.A. Ottoboni,
a toxicologist with the California Department of Health Services:
There is a wealth of
data in the scientific literature on the toxic effect of PCBs. Acutely,
PCBs are of a sufficiently low order of toxicity by all three routes
of exposure [dermal, inhalation, oral] to be classed as legally nontoxic.(7)
There is some indication
that prenatal exposure to PCBs may affect birth size and, to a lesser
extent, gestational period. A comparative study was conducted of 242 newborn
infants whose mothers consumed fish from Lake Michigan and 71 infants
whose mothers did not eat such fish. PCB exposure was indirectly determined
by contamination levels in fish and directly from serum levels in the
umbilical cord. Exposed infants were 160 to 190 grams lighter than the
control group and their heads were 0.6 to 0.7 centimetres smaller. Head
circumference was disproportionately small in relation to both birth weight
and gestational age. The gestation period for women who consumed Lake
Michigan fish was 40.31 weeks, as compared to 40.82 weeks for the control
group. Control analyses showed that none of these effects was attributable
to 37 potential confounding variables, including socio-economic status,
maternal age, smoking during pregnancy, and exposure to polybrominated
biphenyls.(8) It should be emphasized,
however, that this study does not prove that PCBs were the causative agents.
Fish in the Great Lakes are contaminated with dioxins, furans and a wide
variety of industrial and agricultural chemicals, any one or combination
of which might have caused the observed reduction in infant development.
PCBs are routinely described
as "cancer-causing" or sometimes more conservatively as "linked
to cancer." This link is based upon the United States Environmental
Protection Agency (EPA) decision to classify PCBs as potential carcinogens,(9)
but it is tenuous.
One means by which a chemical
can lead to cancer is by causing a mutation in a cell's genetic material.
PCBs have been investigated for mutagenic activity against several standard
test strains of bacteria, the fruit fly Drosophila melanogaster,
human lymphocyte cells, and in vivo with rats. All test results
Whether or not a chemical
is carcinogenic can often be determined by conducting statistical studies
of human populations subjected to long-term exposure. An epidemiology
study of approximately 2,600 electrical industry workers in the United
States indicated a slightly higher than normal incidence of death from
rectal and liver cancers.(11) A
study of Italian electrical workers suggested an increase in the rates
of digestive tract cancers.(12)
The fact that the two groups of workers had different types of cancer
casts doubt on PCBs as the causative agent, however. The statistical significance
of these studies has also been a point of controversy;(13)
it is claimed that the slightly increased incidence of cancer could have
been due to the presence of other chemicals in the workplace or to lifestyle
characteristics (alcohol consumption, low-fibre diet, etc.).
PCBs are fat-soluble compounds
that tend to bioaccumulate along the food chain. Canadian aboriginal people,
particularly those who eat substantial quantities of fish and game, have
been found to possess relatively high concentrations of PCBs in their
body fat. For example, the breast milk of Inuit women in Quebec contains
the world's highest concentration of PCBs.(14)
Even so, Health Canada(15) and Indian
and Northern Affairs Canada(16)
advise aboriginal women to breast-feed their babies on the grounds that
the benefits far exceed any risk. In addition, it is noteworthy that aboriginal
women have the lowest incidence of breast cancer in Canada and that Canada's
Indian population has a significantly lower death rate due to cancer than
has the Canadian population as a whole(17)
(156 versus 170 cancer deaths per 100,000 population per year(18)).
This information does not prove that PCBs do not cause cancer but it does
indicate that current PCB body-fat levels do not place Canadian aboriginal
populations at risk for cancer.
The EPA decision to classify
PCBs as potential carcinogens was based on animal studies. Some rats fed
high concentrations of PCBs over a long period were observed to have developed
liver nodules and hepatomas. One might assume that these studies would
have definitively established PCBs as human carcinogens; this is not so,
however, as the testing procedures did not simulate real-life conditions.
Assuming that humans have
the same cancer response to PCBs as do rats, then a daily PCBs dose of
7.7 mg per kg body weight per day should induce liver cancer.(19)
In the United States the average individual has a PCBs intake of 0.000014
mg per kg body weight per day.(20)
Accordingly, the amount of PCBs one would have to consume daily to develop
liver cancer is 550,000 times greater than the level normally available
in the environment. Further, one would have to ingest this large dose
of PCBs every day for an extended period of time. For example, the experiment
that indicated a higher-than-expected incidence of liver cancer in rats
was conducted for 638 days.(21)
It is unlikely that anyone would be exposed to such high PCB doses over
such a long period.
Such cancer data serve little
real-world purpose and call for an explanation of why they were generated.
The International Agency has established international standards for cancer
research and carcinogen classification for Research (IARC). In cancer
testing, it is often very difficult and time-consuming to establish cause
and effect when the suspected carcinogen is present at normal environmental
or occupational concentrations. The entire testing procedure can usually
be speeded up by subjecting animals "to a maximum tolerated dose
of a substance over their lifetimes."(22)
In cancer studies such "heroic dosing" can save both time and
money; however, it can also lead to data of questionable utility when,
as in the case of PCBs, massive doses of a relatively non-toxic substance
This abberation in the IARC
cancer-testing methodology is a recognized problem and efforts are being
made to change either the methodology or the IARC carcinogen classification
system.(23) Reform in this latter
area is hampered by the fact that the world needs a standardized cancer-testing
regime and the IARC system has been in effect for some time. Theoretically,
this system should not cause problems; knowledgeable professionals usually
ignore non-real-world data. For example, in the United States neither
the American Conference of Governmental Industrial Hygienists nor the
Occupational Safety and Health Administration, both of which are concerned
with the establishment of safe chemical exposure limits in the workplace,
lists PCBs as a suspected human carcinogen.(24)(25)
Problems do arise in the
environmental field, however, for the EPA strictly adheres to the IARC
system.(26) Once the EPA lists a
chemical as a possible carcinogen, environmental groups and the media
are at liberty to describe that chemical as cancer-causing or linked-to-cancer.
On a positive note, the EPA recently announced that it has begun the process
of revising its guidelines for carcinogenic risk assessment. The new system
will take into consideration "realistic exposure scenarios and mechanisms
[of action] when calculating a chemicals's hazard to humans."(27)
BAN AND DESTROY ALL PCBs?
PCBs exhibit two characteristics
that justify the Canadian decision to ban, collect and systematically
destroy all such chemicals. First, PCBs are such extremely stable compounds
that they are nearly indestructible in the natural environment. Like many
xenobiotics (man-made chemicals with no precedence in nature), PCBs have
very few natural enemies. That is to say, microorganisms that normally
degrade and recycle wastes have been slow to evolve and develop enzyme
systems capable of the dedicated total degradation of PCBs. Many xenobiotics
are reactive, and susceptible to light, chemical or thermal decomposition.
In contrast, the chlorination of biphenyl rings produces a chemical structure
of exceptional stability, which is highly resistant to physio-chemical
reactions. As a result, PCBs manufactured in the 1930s are with us today
and will persist for centuries unless incinerated at high temperatures
or destroyed by one of the new destruction technologies under development.
This environmental persistence has resulted in the dispersion of PCBs
to all reaches of the globe.
The second problematic characteristic
is that PCBs are highly fat soluble and conversely highly water insoluble.
Thus, when they are ingested, primarily from fish, they are not readily
eliminated from the body in the urine. Rather, they dissolve in digestive
fats and become absorbed and accumulated in the fat reserves of the body.
The concentration of PCBs accumulated in fat increases with progression
up the food chain. While ill-health cannot be correlated with the current
PCB body-fat loads of Canadians, it can be the argued that continued use
and unrestricted disposal of PCBs might lead to ever higher body loads
with unknown and possibly deleterious consequences.
NATIONAL INVENTORY OF PCBs
The federal government decision
to ban, collect and destroy all PCBs necessitated the compilation of a
national PCB inventory. Between 1929 and the late 1970s, 40,000 tonnes
of PCBs were imported into Canada. No PCBs were manufactured in Canada.
An inventory published by Environment Canada in 1985 accounted for 24,300
tonnes of PCBs, either in storage or in use in electrical equipment.(28)
It is assumed that the PCBs not accounted for have either entered the
environment,(29) or are contained
in a few, as yet unaccounted, for pieces of equipment. In 1988 the Canadian
Council of Resource and Environment Ministers published a national inventory
of PCB waste storage sites.(30)
This inventory identifies the owner or operator by company name and address
and volumes of waste. The waste is characterized as "high concentration,"
"low concentration" or "concentration unknown."
The PCB inventory is not
static. As PCB-containing equipment is retired, the PCB inventory at a
site will increase. PCBs may be moved in efforts to consolidate stored
materials, and PCB inventories will diminish as PCBs are destroyed. PCB
storage regulations require the maintenance of accurate records so that
at any one time the location and amount of Canada's PCBs are known; however,
the original or "master" PCB inventory is updated only periodically.
Since 1988, virtually all
waste PCBs in the province of Alberta have been incinerated. In Labrador,
a federally operated mobile incinerator has destroyed 3,500 tonnes of
federally owned PCB-contaminated wastes collected from abandoned military
sites. In addition, PCB-contaminated oils and tars are being incinerated
as part of the clean-up of the Sydney tar ponds in Nova Scotia.
In a judgment handed down
on 23 January 1992 in Friends of the Oldman River Society v. Canada,
the Supreme Court of Canada stated that the environment is a shared jurisdiction.
This is very much the case with the management of waste PCBs. The federal
government, as stated in Canada's Green Plan, is obligated to destroy
all federally owned PCBs by 1996. The destruction of privately owned or
provincially owned PCBs is the responsibility of the provinces. To date,
Alberta is the only province to have established a PCB incinerator and
to have essentially destroyed all stocks of waste PCBs. Private Albertan
companies are responsible for paying the cost of PCB transportation to,
and for PCB incineration at, the Alberta Special Waste Treatment Centre
in Swan Hills.
As described below, the
federal government has enacted a number of regulations to ensure the safe
management of PCBs. These regulations serve as a minimum standard across
Canada. The provinces may enact their own PCB regulations; however, these
regulations should be equivalent to or more stringent than the federal
regulations. For example, the federal government has set a minimum "destruction
and efficiency" standard of 99.9999% for PCB incinerators. This does
not mean that the provinces must destroy their PCBs by incineration, but
it does obligate them to set 99.9999% as the minimum destruction and efficiency
standard for whatever destruction technology they choose.
HAZARDOUS WASTE MANAGEMENT REGULATIONS
The Canadian Environmental
Protection Act (CEPA) consolidates previously existing legislation
and new, and potentially far-reaching, provisions on toxic substance management.(31)
In addition, the Transportation of Dangerous Goods Act regulates
the transport of hazardous wastes, including PCBs. This Act outlines the
proper handling, packaging, and labelling of transported goods, and safety
during transport. Generally, the federal regulations and guidelines for
collection, transportation and storage are the same for all hazardous
wastes, including PCBs. Additional regulations for PCBs have been enacted
for, unlike hazardous wastes that may be degraded by a variety of processes
or recycled, PCBs may have to undergo long-term storage before they are
destroyed. These additional regulations are the: Federal Mobile PCB Treatment
and Destruction Regulations (3 January 1990), PCB Waste Export Regulations
(15 August 1990), Storage of PCB Wastes Interim Order (13 October 1990),
and the Chlorobiphenyls Regulations (13 March 1991).
The Federal Mobile PCB Treatment
and Destruction Regulations set PCB clean-up and emission standards for
mobile incinerator systems. For example, the PCB destruction and removal
efficiency for a mobile unit is set at no less than 99.9999%. Very stringent
environmental emission standards for dioxins, furans, hydrogen chloride,
and particulate matter are set. The efficiency of a mobile unit must be
tested prior to and during operation and the regulations outline the tests
to be performed. Test results must be submitted to the Minister of Environment
in writing within 60 days of test completion.
The PCB Waste Export Regulations
prohibit the export of any PCB wastes. Export to the United States EPA
is exempt, as is the export of equipment in good working order that contains
less than 500 g of PCB. The purpose of these regulations is to eliminate
the risk of a spill of Canadian PCBs in a foreign country or on the seas
during transport and to improve international relations and prestige through
the government's commitment to manage all Canadian PCBs in Canada.
The Storage of PCB Wastes
Interim Order encompasses and extends previous hazardous waste storage
regulations and guidelines, giving special attention to:
fire control (drums
piled only two high, PCBs separated from other materials by a fire-resistant
barrier or sufficient space to prevent combustion, exhaust system
equipped to limit/contain release of smoke in event of a fire, rust
prevention on drums, fire control and emergency procedure plans developed
in consultation with fire department, alarms, equipment); and,
The Chlorobiphenyls Regulations,
which revoke and replace Chlorobiphenyl Regulations Nos. 1, 2 and 3, prohibit
the manufacture, processing, use, offer for sale or import of chlorobiphenyls.
They set the maximum concentrations or quantities that may be released
into the environment in the course of a commercial, manufacturing or processing
activity and limit to 50 ppm the concentration of PCB in any product or
piece of equipment manufactured or imported into Canada.
To date, incineration is
the only proven, relatively low-cost means of total destruction of PCBs.
PCBs are very stable molecules with a very high temperature of combustion;
they are generally incinerated at temperatures of 1200° C or higher. Thus,
incinerators for PCBs require special high temperature design and accordingly
are more expensive to build and operate than the conventional incinerators
used for most organic hazardous wastes. Incinerators designed for PCB
destruction can, however, be used subsequently for the incineration of
other wastes at reduced temperature and expense. Maintenance of a high
flue gas temperature before, during and after the PCB incineration guards
against the generation of dioxins and furans, while scrubbers ensure that
carbon dioxide and water vapour are essentially the only stack emissions
released to the atmosphere. PCB incinerators operate at between "six
and eight 9's" (99.9999 -99.999999%) of destruction and removal efficiency.(32)
There are three types of
PCB incinerator: liquid injection, rotary kiln, and high-efficiency boilers.
In Canada, the rotary kiln incinerator appears to be the technology of
choice as it can handle both PCB-contaminated solid wastes and liquid
PCBs. The Swan Hills incinerator and the Labrador mobile unit are both
In spite of the exceptional
efficiency of today's toxic waste incinerators, a German company, BASF,
has improved upon the technology.(33)
BASF developed a catalyst (titanium, vanadium oxide and tungsten oxide)
that destroys chlorinated organic compounds, converting them to carbon
dioxide, water vapour and hydrogen chloride. The catalyst, by not allowing
the formation of elemental chlorine, ensures that new chlorinated compounds
are not created in the flue gas, thus reducing the need for scrubbers.
In addition, the catalyst keeps on working for up to three hours. This
has two advantages: it saves on after-burn fuel costs and it ensures a
continued clean burn in the event of a plant emergency.
Virtually all environmental
groups who campaign against toxic chemicals are unanimously opposed to
incineration as a toxic waste management strategy. These groups promote
the belief that incineration simply takes a concentrated toxic waste and
disperses toxic fumes through the air over a wider area. Although this
allegation is no longer valid, there are some historical data to support
it. Up to approximately 30 years ago it was common practice in North American
cities to burn garbage in municipal solid waste incinerators that were
not equipped with any sort of pollution-control device. Today, soil analyses
in the vicinity of these old incinerators still reveal the presence of
dioxins and furans. It could therefore be argued that incineration takes
PCBs and thermochemically transforms a portion of them to the more toxic
and truly carcinogenic compound dioxin.(34)
Nevertheless, a simple mathematical
check shows that the dioxin risk posed by a PCB incinerator is indeed
minimal. A high-temperature burn of chlorinated organic compounds can
generate a dioxin flue gas concentration of 5 to 50 ppm.(35)
In a worst-case PCB-incineration scenario, the dioxin concentration would
be 50 ppm and the incinerator would be operating at the minimum destruction
and efficiency standard permitted (99.9999%). Under these conditions,
out of every million organic molecules generated by the burn only one
molecule would escape to the atmosphere; the chance of that molecule being
dioxin is one in 20,000.
that any exposure to dioxin, no matter how small, represents an unacceptable
health risk. This may be true; however, every day virtually everyone on
this planet is subjected to dioxins from uncontrolled emissions of cigarette
smoke, wood smoke, and furnace gases. According to a Japanese study:
The concentration of
PCDDs [dioxins] in cigarette smoke was similar to that found in the
flue gas of a municipal waste incinerator. However, the presence of
PCDDs in cigarette smoke is more significant than that in the flue
gas because cigarette smoke is inhaled directly into the lungs without
diffusion and/or dilution.(36)
The decontamination of mineral
oils containing up to a few thousand ppm of PCBs can be achieved by a
chemical-sodium process. Here, the sodium reagent strips chlorine atoms
from the PCB molecule and produces polyphenylene and sodium chloride.
The mineral oil in which the PCBs were dispersed is unchanged and can
be reused. Unfortunately this process has a number of disadvantages: it
is very expensive, it produces a large salt waste stream, it cannot be
used in cases where the oil also contains significant amounts of contaminating
water, and it is appropriate only for the clean-up of oils containing
low concentrations of PCBs. In 1991, the German company Degussa announced
a new sodium-based process that it claims will detoxify oils at low cost;(37)
however, further details have not been made available.
A Canadian company, Eco
Logic of Rockwood, Ontario, has developed a thermo-chemical process whereby
the PCB wastes are placed in a closed vessel and hydrogen is injected
to replace air as the headspace gas. When oxygen is eliminated in this
manner the PCBs cannot be oxidized to dioxins. The reaction is started
by heating the reactor contents to temperatures above 850oC. The PCBs
undergo a chemical reduction reaction whereby each of the chlorine atoms
is replaced by a hydrogen atom. The hydrogenated biphenyl rings then cleave
to produce two molecules of benzene. The released chlorine atoms react
with more hydrogen to form hydrochloric acid. Finally, the hydrochloric
acid is treated with sodium bicarbonate to produce sodium chloride and
This Canadian process has
a number of advantages. Most important, it emits no flue gases and can
therefore be marketed as a "closed system." The apparatus is
not large and can be used as a mobile facility. In addition, the process
produces two commercially valuable commodities, benzene and methane. In
controlled laboratory conditions, destruction and efficiency levels of
99.9999% have been achieved. Environment Canada and the United States
EPA are jointly funding a pilot study to determine if the same level of
destruction and efficiency can be duplicated under "use" conditions
for a variety of PCB wastes. The process is not without its disadvantages,
however. It produces a salt waste stream, and treatment costs can run
up to $1,000 per tonne.
It should be noted that
two substances in the Eco Logic process, hydrogen and benzene, are potentially
hazardous in an emergency situation. Hydrogen is an extremely explosive
substance, while benzene is both very toxic and a recognized carcinogen.
Chronic exposure to benzene causes depression of bone marrow activity,
aplasia (tissue or organ failure to develop), and leukemia. Acute exposure
may result in irritation of mucous membranes, restlessness, convulsions,
excitement, depression and death from respiratory failure.(39)
Australian researchers have
patented a mechano-chemical process for the degradation of PCBs and other
chemical wastes. This is a closed system where PCB wastes and a reactant
such as calcium oxide is placed in a ball mill containing steel balls.
The colliding balls are said to activate chemical reactions resulting
in "virtual" breakdown of the waste to environmentally harmless
products such as carbon, calcium hydroxide and calcium chloride at a destruction
and efficiency level of 99.996%. Unlike other PCB destruction processes,
this system requires no heat input. In addition, it can be used as a mobile
facility.(40) Critics of the system
point out that the technique is still in an early development stage and
there are as yet insufficient data to judge the validity of process claims.
Scepticism tends to be high as another process using calcium oxide was
shown to volatilize PCBs rather than degrade them.(41)
The Biological Sciences
Laboratory of General Electric Co., Schenectady, N.Y. is conducting research
on the biological degradation of PCBs. Until the early 1980s it was firmly
believed that PCBs were biologically indestructible; however, analysis
of a 30-year-old PCB dump in the oxygen-depleted (anaerobic) sediments
of the Hudson River show PCBs to have been largely dechlorinated by the
action of anaerobic bacteria. Transfer of these dechlorinated biphenyl
rings to an aerobic atmosphere resulted in further degradation by oxidative
It is believed that, during
the 30-year incubation of PCBs in the presence of anaerobic bacteria,
sufficient evolution and genetic exchange occurred to produce new strains
of PCB-dechlorinating bacteria. General Electric is carrying out research
and development work to optimize a sequential anaerobic-aerobic process.
Genetic engineering work is also underway to place all the necessary genes
in one microorganism so the process can be accomplished in one step.(43)
This is a long-term research project, and its successful commercial application
may be many years, if not decades, in the future.
Following the PCB fire in
St.-Basile-le-Grand in August 1988, federal and provincial regulations
and monitoring of hazardous waste storage and destruction facilities have
become much more stringent and there have been no reports of major accidents
or releases of PCBs from storage sites or hazardous waste transfer stations.
There have, however, been, a few reports of minor leaks and spills and
PCBs were spilt on the road in a highway accident.
Hazardous waste and PCB
storage sites now appear to be well operated and safe. This is not to
say that the storage of hazardous wastes should be considered as a waste
disposal solution. No matter how safe a storage facility, there is always
the possibility of a chemical disaster due to arson or a catastrophic
act of nature. Further, the economic burden means that indefinite storage
of toxic wastes such as PCBs cannot be seriously considered. Indeed, the
cost of "in-perpetuity" storage might induce owners not to declare
PCB inventories and to dump the chemicals illegally into landfills, sewers,
The Canadian effort to manage
waste PCBs effectively has been stalled by misconceptions held by the
public. The federal and provincial governments must carry some of the
responsibility for this. Though this paralysis is costing Canadian tax
payers and businesses enormous sums of money in maintenance, supervision
and inspection of PCB storage sites, governments have made very little
effort either to disseminate PCB facts or to counter PCB myths.
The Green Plan calls for
the destruction of all federally owned PCBs by 1996 and the government
has initiated a consultative procedure to ensure public participation
in the decision-making process for the siting of mobile incinerators.
It is questionable, however, whether members of a community are capable
of reaching an informed decision on this subject if they have only their
fears and scant factual knowledge of PCBs or PCB incineration to guide
them. Indeed, even the well informed individuals in a community will oppose
local PCB incineration on the grounds that resulting neighbourhood fears
and sensational media reports would lower property values.
An additional problem confronting
Canada's PCB destruction program stems from the actions of some environmental
groups. Although these groups support the elimination of PCBs, they are
so opposed to incineration that some attempt to block even equipment testing.
No matter what technology is used to destroy PCBs, it is essential that
all equipment undergo rigorous quality-control testing to supply the critical
data needed for comparing competing technologies and to ensure that the
chosen technology will meet federal emission standards. In the United
States, an environmental group obtained a court injunction to block a
1993 EPA test burn at the state-of-the-art Von Roll toxic waste incinerator
in East Liverpool, Ohio.(44) In
Canada, opposition to, and criticism of, test burns at both the Sydney
tar ponds and the Labrador mobile PCB incinerator received widespread
Given the opposition to
quality-control tests for incinerators, it should not be expected that
alternative technologies will receive carte blanche acceptance. Indeed,
scepticism towards and resistance to these technologies could be expected
since, as yet, none of them has achieved the eight 9's level of efficiency
and destruction demonstrated by the best PCB incinerators.
Misinformation and a failure
to dispel environmental misconceptions have greatly impaired the effectiveness
of Canada's PCB destruction program. As a result, PCBs are being relegated
to long-term storage, the solution that poses the greatest threat to the
M.J. Charles and R.A. Hites, "Sources and Fates of Aquatic Pollutants,"
Advances in Chemistry, Vol. 216, 1987, p. 365-389.
Canadian Council of Resource and Environment Ministers, The PCB Story,
August 1986, p.2.
In this conversion, the phenyl rings of the original PCB are cleaved
apart, but still bonded through one oxygen bridge to form a furan, or
through two oxygen bridges to form a dioxin.
Environment Canada, Polychlorinated Biphenyls (PCBs) Fate and
Effects in the Canadian Environment, Beauregard Press Limited, EPS
4/HA/2, May 1988, 90 p.
M.A. Ottoboni, The Dose Makes the Poison: A Plain-Language Guide to
Toxicology, Bacchus Press, Berkeley, 1984, p. 163-167.
G.G. Fein, et al., "Prenatal Exposure to Polychlorinated Biphenyls:
Effects on Birth Size and Gestational Age," Journal of Pediatrics,
Vol. 105, 1984, p. 315-320.
Environmental Protection Agency, Ambient Water Quality Criteria for
Polychlorinated Biphenyls, U.S. Environmental Protection Agency, EPA
Environment Canada (1988).
D.P. Brown and M. Jones, "Mortality and Industrial Hygiene Study
of Workers Exposed to Polychlorinated Biphenyls," Archives of
Environmental Contamination and Toxicology, Vol. 36, 1981, p. 120-129.
P.A. Bertazzi, et al., "Mortality Study of Male and Female
Workers Exposed to PCBs," Proceedings of the International Symposium
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