TL: DIOXINS, FURANS AND PCBS: THE TRUE STORY (GP) SO: Greenpeace Canada DT:1991 Keywords: toxics dioxins furans pcbs human health risks greenpeace canada gp reports / Dioxins, furans and PCBs have become some of the most controversial chemicals of modern society. Dioxin in particular has been labelled the most toxic chemical ever produced by man. More than $1 billion has been spent so far on dioxin research, yet at the same time, industry and government officials insist that not enough evidence on the toxicity exists to justify elimination of the sources. This paper explores some of the myths and facts surrounding these environmentally dangerous chemicals and explains why the scientific debate has become of an increasing political nature. What Are 'Dioxins' ================= The term 'dioxins' usually refers to a whole chemical family with 75 individual members, which more correctly should be termed chlorinated dibenzo-p-dioxins. The most toxic member of this family is 2,3,7,8-Tetra-Chloro-Dibenzo-p-Dioxin, often abbreviated as 2,3,7,8-TCDD. Often, the term 'dioxins' also includes a closely related chemical family called chlorinated dibenzofurans. The most toxic among the 135 known furans is 2,3,7,8-Tetra-Chloro-Dibenzo-Furan (TCDF), which is one tenth as toxic as the corresponding dioxin, TCDD. Of the 210 dioxins and furans, twelve are extremely toxic and are commonly referred to as the 'Dirty Dozen'. Their individual toxicity is ranked by comparing them to 2,3,7,8-TCDD via internationally agreed upon Toxic Equivalence Factors (TEFs). Box 1 (next page) shows the chemical structures of dioxins and furans, and their toxicity ranking. PCBs are another chemical family closely related to dioxins. Due to their similar chemical structure, some PCBs can act through exactly the same pathways in organisms as dioxins, but are much less potent. However, due to their chemical nature, PCBs are inevitably contaminated with furans and dioxins, and will form these more toxic chemicals during fires. How Toxic Are Dioxins ===================== a) Extreme Ability to Kill. Dioxin TCDD is the most toxic manmade chemical ever tested on laboratory animals. Acutely lethal doses are measured in micro-grams per kilogram animal weight, in the parts per billion range. Though the lethal dose varies considerably from species to species, dioxin has been found to be extraordinarily toxic to all species tested. Characteristic of lethal dioxin exposure is the 'wasting syndrome': animals seem to waste away, and eventually die, without displaying any overt pathological symptoms. The exact reason why dioxin can cause death in these minute quantities is not yet known. b) Extremely Bio-Accumulative Dioxins are some of the most persistent and bioaccumulative man- made chemicals released into the environment. While dioxins can be broken down under certain conditions, in particular when exposed to intensive sunlight, they cannot be broken down once absorbed by soil or dust.When they enter the food-chain, they will biomagnify, often to levels many thousands of times higher than their surroundings. It is this combination of dioxin's extreme toxicity and its biomagnification in the environment that makes Greenpeace believe that there can be no safe level of dioxin emissions. c) Long-Term Toxicity. The Dioxin-Receptor More worrisome than the high acute toxicity are the more insidious long-term effects of exposure to sub-lethal doses of dioxin. Daily doses 1,000 times below the lethal dose, the parts per trillion range, cause profound delayed effects in mammals, such as cancer, damage to the immune system and reproductive failure. Concentrations in water another 1,000 times lower, the parts per quadrillion range, can still cause a wide variety of toxic effects in fish, e.g. in rainbow trout. Scientists believe that the reason why dioxin is so toxic in minute quantities lies in its mode-of-action inside the cell. Dioxin imitates natural steroid hormones (e.g. estrogen) in our bodies. Dioxin fits into a protein receptor, which normally responds to these steroid hormones. The receptor then transports the dioxin directly into the cell nucleus, where it interacts with basic cell chemistry. The 'dioxin-receptor' has been identified in laboratory animals as well as in humans. One can compare this mode-of-action with dioxin acting as a key to the receptor-lock. Some individual dioxins and furans fit better into the receptor than others; PCBs do not fit as well. 2,3,7,8-TCDD fits best into this receptor and consequently is the most toxic. d) Chloracne The disfiguring skin disease chloracne is often erroneously referred to as the only human health effect positively linked to dioxin exposure, and is often down-played in its severity. Yet, chloracne is always accompanied by other health effects, such as chronic weakness in the legs, severe pain in the joints, headaches, pronounced fatigue and irritability, and often lasts for decades, as several studies on occupationally exposed workers show. e) Cancer 2,3,7,8-TCDD is the most potent carcinogen tested to date. Researchers so far have been unable to clarify whether dioxin acts as a co-carcinogen or whether it suppresses the immune response to other carcinogens. Yet given the fact that other carcinogens are plentiful in our polluted environment, that question can be of academic interest only. Does Dioxin Cause Cancer in Humans? Much discussion has focused on whether 2,3,7,8-TCDD is a human carcinogen. Some evidence exists to support such a claim, but there are also indications that this discussion has not been without bias. One of the best analyzed groups of exposed humans are chemical workers who produced 2,4,5-T (Agent Orange). The West German chemical company BASF experienced an explosion in 1953, which exposed workers to relatively high doses of dioxin TCDD. Many of the workers subsequently suffered from chloracne. At the 1989 lnternational Symposium on dioxin and its toxic effects, West German scientist F. Rohleder presented a re- analysis of these exposed BASF workers and found significantly elevated levels of respiratory cancer and cancer of the digestive system. Most disturbingly, Rohleder found that earlier studies, paid for by BASF itself, were fraudulent: non-exposed workers had been deliberately added to the 'exposed' cohort, and truly exposed workers, some of whom were displaying chloracne, had been deliberately excluded from the study. Evidence that PCBs may be carcinogenic in humans is also mounting. A cancer study by the Cincinnati National Institute for Occupational Safety and Health found that Westinghouse workers in Bloomington, Indiana experienced a more than two-fold increase in mortality from brain cancer and a four-fold increase in deaths from skin cancer. The Shortcomings of Epidemiology The reason clear proof of dioxins' and PCBs' carcinogenicity in humans does not exist, and may never exist, lies in some important short-comings of any epidemiological study: the humans investigated are exposed to many more toxic influences than just dioxin, and it will always be possible to point the finger at other factors possibly causing the disease. This poses an ethical dilemma, since it is impossible to raise humans in controlled environments such as a laboratory. Further, epidemiological studies carried out so far rarely have verified the actual exposure of the presumed exposed versus the unexposed control group. That fact is probably the single most important reason why the findings of epidemiological studies carried out so far contradict each other so much. Recently it has become possible to determine actual dioxin body burdens through analysis of blood serum, and some exposed cohorts investigated earlier, e.g. Vietnam Veterans and occupationally exposed workers, are being re-analyzed. However, individuals in these cohorts who have died since the original study was conducted are invariably excluded from these new studies. f) Reproductive Effects More subtle than chloracne or cancer are other health effects such as reproductive failure. It is striking that reproductive failure has been observed in all animal species tested, be it fish, bird or mammal. It is therefore highly likely that reproductive failure also occurs in humans exposed to dioxin. Most disturbing are laboratory experiments on primates such as rhesus monkeys, whose reproductive systems were found to be extremely sensitive to dioxins when administered in minute doses on a daily basis. Researchers found a serious decrease in sperm count in exposed males, and an inability to conceive or carry the pregnancy to term in exposed females. Some evidence of such reproductive failure in humans already exists. Jock Ferguson, a Canadian reporter who investigated health effects in occupationally exposed workers, once interviewed three Hooker Chemicals workers, all of whom suddenly came to realize that none had fathered children. Why is it that incidences like these are always dismissed immediately as anecdotal evidence, and are not followed up in a formal investigation, e.g. an epidemiological study, whereas negative findings are always promoted as certainty? Other reproductive effects observed in laboratory animals include stillbirths and birth defects. Dioxin has been linked to spina bifida, anencephaly (absence of brain) and cleft palate. g) Suppression of the Immune System Perhaps most frightening of all are the effects dioxin has on the immune system. The thymus, a gland that is of utmost importance to the immune system, is one of the main targets of dioxin. It has been shown in laboratory animals that one of the first signs of dioxin poisoning is thymic atrophy. The human thymus develops at 9 weeks of gestation and disappears at puberty, at the age of 10 to 12. it seems that the thymus is not required for the maintenance of effective immune function in adults, since human T lymphocytes have a life-span of 15 - 20 years, and there is little replacement for them during adult life. But what about children, and even worse, what does thymic atrophy do to nursing babies? h) Behavioral Changes in Offspring and Minimum Effect Levels A number of health effects have been noted at doses comparable to those producing cancer. Very few of the studies, however, have produced clear No Observable Effect Levels. This is particularly true of long-term studies in rodents and rhesus monkeys. The available evidence suggests that No Observable Effect Levels for some of the immunologic and reproductive effects in rhesus monkeys are well below 1 ng/kg/day. Behavioral changes in the offspring, for example, were observed in rhesus monkeys when exposed to dioxin levels in the diet as low as 0.12 parts per trillion. Dioxins in Human Milk An average breast-fed baby in industrialized countries already ingests up to 100 times more dioxin than the World Health Organization (WHO) deems tolerable for a healthy adult. The margin of safety, that is the difference between the levels of dioxin we expose our babies to and those that we know will cause adverse effects in laboratory animals, is on the order of ten to non-existent. Babies in heavily contaminated areas are already exposed to dioxin levels that are certain to induce toxic effects in laboratory animals. Aside from dangerously high levels of dioxins and furans, mother's milk also contains other toxic chlorinated chemicals, such as PCBS, hexachlorobenzene, and polychloro-naphthalenes to name a few. Yet no research has been done on the likely synergistic effects of these compounds. Further, some scientists believe that exposure in utero from transplacental migration may have important effects on brain development, and thus may be of even more concern than postnatal exposure through mother's milk. Scientists will never be able to prove a link between health effects at a later stage in life to any toxic chemicals present in mother's milk or to exposure to these toxins in utero, simply because babies do not grow up in controlled environments such as a laboratory. Who is at Risk? Obviously, the human baby is of most concern when it comes to human health effects. But what about the entire environment? Despite all the money spent and all the papers published, we know very little about dioxin's effect on an entire ecosystem. It seems likely that animals and birds with a fish-based diet will suffer most. The Baltic gray seal is a case in point. In the mid-seventies it was found that only 20 percent of the mature female gray seals were fertile.' This is commonly thought to be caused by PCBs in the Baltic food chain; and PCBS, as we know, react through the same protein receptor as dioxins. Fertility is not the only effect linked to PCBs in the seals' diet: over 75% of the seals found dead in recent years have been found to have intestinal ulcers and kidney damage. Roughly half the female gray seals also had uterine tumors. Often, even the living display these same diseases. Interestingly, when seals are raised with a diet of less contaminated fish caught outside the Baltic, the seals are able to reproduce. Yet, this fact is often excluded in discussions about toxic effects of PCBs and dioxins, and seldom mentioned in official government or industry brochures. Clearly, the solution to such environmental problems cannot be to place Baltic seals or beluga whales or fish-eating birds into a sanctuary and feed them less contaminated fish. Neither can the solution be to forbid breast-feeding. It is essential, then, to prevent any further build-up of these insidious chemicals in the food chain. This can only be achieved by immediate elimination of all sources of dioxins. The Sources and Elimination Strategies While the production of PCBs was finally outlawed worldwide, and the worry now is how to eliminate existing PCB wastes, dioxins and furans seem to come from many different and ongoing sources. Yet there is an obvious common denominator to these sources: modern society's use of chlorine. It is often claimed that dioxin is a naturally occurring toxin, produced in forest fires and wood stoves. This theory, first introduced by Dow Chemical scientists as the 'Trace Chemistry of Fire' theory, has been convincingly disclaimed by at least three separate studies: a) the Czuczwa study, which investigated contamination of Great Lakes sediments, found that dioxin levels were virtually non-existent prior to the Second World War, which coincides with the beginning of large-scale production and combustion of organochlorines. b) the Inuit mummy study, in which A. Schector investigated tissue of two 400-year-old mummies. Only minor amounts of the less toxic but very persistent octa-chlorodibenzo-p-dioxin (OCDD) were found. c) the Chilean mummy study, in which W.V. Lignon analyzed tissue of nine Chilean mummies for dioxins and furans. Again, only minor amounts of OCDD were found. All three studies conclude that rising dioxin levels are intimately linked to modem industrialized society. Box 3 lists strategies to eliminate major industrial sources of dioxin, all of which are connected with the use of elemental chlorine as well as the production and combustion of chlorinated organic chemicals (organochlorines). Elemental chlorine does not exist in Nature, and Nature does not produce organochlorines on a large scale either, with the exception of some very simple molecules, such as methylchloride or dichloromethane. Many of the industrial dioxin sources are easy to eliminate. Chlorophenols, for example, are already banned in many European countries. Sweden actually experienced a decline of dioxin levels in human milk after banning both pentachlorophenol and chlorophenolbased herbicides. Both Canada and the United States actively resist such a ban, and chlorophenols are still used for wood preservation (utility poles and railway ties) and as a fungicide on lumber destined for export. Once treated, these wood articles become very significant sources of dioxin when burnt in wood stoves or incinerators. Municipal incinerators are another very significant but completely avoidable source of dioxins. They not only generate vast amounts of dioxin-laden ash but also emit dioxins into the atmosphere where they can be transported over long distances, e.g. to the Arctic. The disposal of toxic incinerator ash has become a highly publicized problem since export schemes to Panama and other developing nations were exposed by Greenpeace. Incinerators should be eliminated for other environmental reasons as well. Incinerators are not compatible with recycling systems, since comprehensive recycling systems eliminate cheap fuel from the waste stream, e.g. paper or plastics, thus eliminating the economic viability of incinerators. Copper reclamation plants and hospital waste incinerators are also major dioxin sources due to the burning of PVC (polyvinylchloride) and PVDC (polyvinylidene-chloride) waste. Copper wires are coated with PVC, and many hospital disposable items are made of these chlorinated plastics, as are many disposable household products. Many West German cities, e.g. Bielefeld, Munich, Aachen and others, have now banned the use of PVC material in public buildings to protect the public and fire fighters from dioxin formed during fires. The Danish government is actively pursuing a phaseout of all PVC articles, and is presently researching a feasible time-table. The Swedish govemment is pushing for a phase-out of chlorinated solvents, due to the risks they pose to ground water supply, their effects in the lower atmosphere, and the associated waste disposal problems. The pulp and paper industry as well as certain branches of the metallurgical industry are significant sources of dioxin due to the use of raw chlorine. Chlorine gas reacts with wood compounds or carbon electrodes to form dioxins. European governments are researching and implementing new production processes that would ban the use of chlorine and thus the generation of dioxin as well as other toxic organochlorines. It is clear that eliminating these sources of dioxin means eliminating a much larger portion of toxic chemicals from our environment. This makes a lot of sense from an environmental point of view, because dioxins never come alone, but are always accompanied by other toxic organochlorines. Dioxin indeed is only the tip of an iceberg of environmentally dangerous organochlorines and other organohalogens; and successfully eliminating modern society's dioxin sources will inevitably mean eliminating this iceberg, which is exactly the reason environmentalists are becoming more and more vocal in this matter. To Greenpeace, dioxin is a symbol of whether we want to deal with our pollution or whether we want to continue our self-destructive lifestyle. The Politics - Whose Interests Are At Stake? Obviously, when the entire organohalogen production is being questioned, some very powerful interest groups want to have a say. Much is at stake, both in terms of liability law suits and lost profits. It would be naive to think that the chlorine- and organochlorine- producing industry, e.g. PVC and chlorinated solvents or pesticide producers, have had no influence on the colour of dioxin science. Other vested parties to name include the incineration lobby, the pulp and paper industry and the metallurgical industry. Even defense departments are involved in the discussion, due to the use of Agent Orange in Vietnam and elsewhere. The result: instead of devoting research efforts toward eliminating the sources, finding alternative products or production technologies, and safe methods of dealing with the existing wastes, the public is being deluged with attempts to linguistically detoxify dioxin, via media releases, information brochures and widely publicized risk assessments. Risk assessments, in particular, can at best only be viewed as pseudoscientific exercises, because they do not take into account: total exposure from all possible sources synergistic effects - effects on the next generation, for example through contaminated human milk all possible health effects, rather than selected health effects only, e.g. certain forms of cancer. Conclusions and Greenpeace Demands ================================== Enough research exists to prove that dioxin is extremely toxic and persistent, and that levels in our environment and in human milk are increasing. Given that many health effects occur from exposure to even minute quantities over time, and that widespread contamination of our environment and the build-up of these chemicals in the food chain has already led to dangerously high levels in human milk and in marine mammals, all energy must be devoted toward preventing any further releases of dioxins into the environment. The elimination of man-made dioxin sources would go hand-in-hand with the elimination of a much larger group of environmentally dangerous organochlorines, which would be extremely desirable from an overall environmental point of view. Elimination of all dioxin sources would mark a turning point in our dealings with pollution control, since a holistic approach would have to include the phase-out of an entire class of anthropogenic chemicals presently discharged in large quantities into the environment. In 1983, after two years of research, the Ministers' Expert Advisory Committee on Dioxins stated that : "Regardless of arguments about the significance of species differences in sensitivity, the validity of risk assessments, and other uncertainties which may take years to resolve, it is quite clear that dioxins are very unpleasant things to have in our environment and the less we have of them the better. It is, in fact, imperative to reduce dioxin exposure to the absolute possible minimum." Despite these recommendations, the Canadian government has failed to eliminate even such outstanding dioxin sources as pentachlorophenol, but has instead actually added new dioxin sources to the Canadian environment by building further municipal and hazardous waste incinerators. Greenpeace demands that the Canadian government follow the leadership provided by forward thinking European governments, and: establish a five-year plan to eliminate all known industrial dioxin sources, and in particular: ban import and use of chloro-phenols immediately; establish an indefinite moratorium on construction of new municipal and hazardous waste incinerators; phase out disposable products made of PVC or *PVDC; phase out PVC coating of copper wire; phase out chlorinated solvents; eliminate the use of chlorine in the pulp and paper industry and metallurgical industry; establish a mass-balance of chlorine and organochlorines in Canada; i.e. determine the amount of chlorine gas and organochlorines produced, and their fate in the environment. This mass balance should extend to other halogens and organohalogens; commission a feasibility study on phase-out of all production and use of organochlorines. Fund research to find clean production technologies and alternatives to chlorinated products, as well as safe methods of destroying the existing piles of dioxin and other chlorinated waste. This paper was researched and written by Renate Kroesa, M.Sc., Toxic Project Coordinator.