CHLORINE AND CANCER
Although, there are still wide interpretations of the possible causes of cancer, here we give an indication of magnitude of the different possible causes:
Expectance of premature cancer:
All figures expressed in percent:
|Expectance of premature cancer|
Bruce N. Ames, the world famous toxicologist, found that when a lot of materials, chlorine containing or not, natural or not, are tested for carcinogenity at MTD (maximum tolerated dose) in rodents, about 50% are found to be positive. According to him, most of this carcinogenesis is due to the high dose, not the carcinogenic potential of the material itself. If the dose is lowered, the results are vanishing rapidly, in general a quadratic dose-response curve can be seen and below a certain dose there is no effect at all. See: Too many rodent carcinogens (not a popular scientific chat!).
Other materials are carcinogens, even at lower dose, but then the carcinogenic effect lowers more in proportion with the magnitude of the dose.
Everybody will have cancer, if he/she will become old enough. The possibility of having cancer is growing exponential with age with 10^4 to 10^5. For mice and rats, that results in about 40% natural cancer deaths at an average two years of age. For humans, who have a different metabolism, this results in a 25% of natural cancer deaths on an average seventy-five years of life.
One of the most common carcinogens, indispensable for life, which is responsible for 10,000 oxidative DNA-adducts (faults in the cell kernel, which can induce cancer) per cell per day, is oxygen. In fact most of this DNA-faults are repaired by some mechanism, but not all. The fear of many people that even one molecule of a carcinogen will cause cancer, can be true, but misses relevance, if you compare that with this natural damage and the enormous amount of natural carcinogens we do digest with our food. See: Dietary Pesticides (99.99% All Natural). If you think that the body treats natural carcinogens differently to synthetic carcinogens, you are wrong. A lot of natural carcinogenic chemicals are introduced only a few hundred years ago to recently in our diet, so our body had not the time to evolve some counteraction. Our body defences are in fact general in nature and treat natural and synthetic chemicals in the same way. See: Nature's Chemicals and Synthetic Chemicals: Comparative Toxicology.
The same material can be an anti-carcinogen at low dose and a carcinogen at high dose. A typical example is vitamin A. At normal dose in food, it is indispensable for growth, night-sight and the immune system. It also seems to help in the prevention of (lung)cancer, because it is an anti-oxidant. At higher dose, about four times the daily average, it augments the possibility of having lung cancer by smokers. At much higher dose it is very dangerous for the unborn child: children are born without brains! And it seems to be carcinogenic itself at very high dose.
There are, just like in the case of toxins (see Chlorine and toxicity) enormous differences between the carcinogenic potency of different materials. If you drink one beer or one glass of wine a day, that can be beneficial for your hart and will not influence your possibility to develop cancer. If you drink more than a hundred grams of alcohol a day, that is five or more glasses, you will raise the possibility of liver cancer. On the other side of the scale, we have nitrosamines (can be formed by too much nitrate in our food) of which a few milligrams a day can be enough to form colon cancer.
Some chlorinated chemicals are found to be carcinogenic, but with the exception of TCDD-dioxin, they are all between the above limits. VCM, the building block for PVC, was found to be a carcinogen around 1970. Before that, a lot of workers had been exposed to massive doses (even more than 1000 ppm - parts per million) of VCM, during years. This resulted in about 170 workers all over the world, who died from angiosarcoma, a specific liver cancer. Immediately after this discovery, the concentrations of VCM in air were rapidly reduced to less than 1 ppm at the workplace, resulting in a possibility of developing cancer of less than 1:100,000.
And what about dioxins, the most toxic product ever made by man (and nature: see Sources of dioxins) That seems to be the same story as for vitamin A: low doses seems to be cancer inhibiting, higher doses are cancer promoting. See How dangerous are dioxins. But that being said, we do not promote the use of small doses of dioxins to prevent cancer!
Recently, the WHO has declared the Seveso type dioxin (2,3,7,8 TCDD) as a human carcinogen, based on the consequences of severe accidents in several chemical works, where workers received extreme high levels of this dioxin type. The rise of cancer incidences in a life time was app. 40% for the highest exposed people. That has to be compared with a 20 times (or 2,000%) rise in cancer incidence for smokers...
The other 209 types of chlorinated dioxins and furans are not classified until now, because of lack of reliable data.
Here we can give you an idea of the relative (possible) carcinogenic potency of different materials. The maximum allowed concentration in air on the working place for 8 hours a day, 5 days a week, 50 weeks a year and 40 years long, which causes less than one extra case of cancer on 100,000 workers is:
(suspect) carcinogenic substances in industry:
maximum allowed at the work environment, all figures expressed in mg/m3 in air
|(suspect) carcinogenic substances in industry|
|1,3 butadiene:||34||cracking, synthetic rubber|
|benzene:||16||crude oil, petrol, cracking|
|carbon black:||3.5||dye, anti-oxidant|
|diesel soot:||0.6||diesel exhaust|
|PAH's (#):||0.1||see benzo(a)pyrene|
|benzo(a)pyrene (#):||0.0005||diesel exhaust, cracking, crude oil, asphalt, burning of organic materials, tar from wood and coal|
|propylene oxide:||6||PET bottles and packing|
|ethylene oxide:||2||PET bottles and packing|
|epychlorhydrin:||12||epoxy resins, coatings, glues|
|TCDD-dioxin:||0.00000005||all incineration, all processes|
|nitrosamines (10 types)||0.0025||synthetic rubber, nitrates in food|
|1,2 dichloroethane (DCE) (*):||40||PVC, amines|
|ozone (since June 1995):||0.1||bleaching, disinfectant|
|cobalt:||0.5||catalyst for phthallic acids and linoleum|
|wood dust (general):||2||construction, floors, furniture, based on wood dust from oak and beach|
(#) Benzo(a)pyrene is the most potent carcinogenic PAH. The potency of a mixture of PAH's is compared for total toxicity by multiplying quantities with toxicity factors, compared to this compound.
As you can see, almost all human activities have to do with carcinogenic substances. On toxicological grounds, even many more materials are suspect carcinogens, but have no certain highest allowable concentrations yet. That is the case for wood dust of all types (oak and beach are already proven human carcinogens), the products from pyrolyses of any organic material, ethylene which reacts in the body like ethylene oxide, but at a 30 times higher concentration in air, formaldehyde, and many more...
Greenpeace is right when they say that more than a hundred chlorine containing compounds are proven carcinogens. In fact this is not much, because average half of the more than 10,000 chlorinated materials will be found to be carcinogenic at some (high) dose.
But the same is true for non-chlorinated materials. If you see the complete list of known carcinogens, the lists of far more potent carcinogen hydrocarbons and nitrogen compounds are much longer.
As far as we know, not one industrial or natural material can be produced without release of carcinogens or other dangerous substances. Sand for glass gives silicosis, crude oil contains hundreds of carcinogenic materials, like benzene, waxes and PAH's. So all from crude oil derived products and the use of oil for energy, releases some carcinogenic materials. Ethylene for polyethylene (PE), butadiene for synthetic rubber, benzene for polystyrene (PS), ethylene oxide for polyethylene terephthalate (PET), wood dust for furniture, tannins and chromium salts for leather, all are dangerous if not carefully treated...
If you look at the air releases of a chlorine-VCM-PVC-factory, there is (in Europe) less than 100 g of VCM that is emitted per ton of PVC. A factory that makes 500,000 tonnes of PVC gives a maximum emission of about 50 tonnes of VCM per year. This seems to be rather much, but this is in fact only 6 kg/h, widespread over a large factory. This is within the factory below all concentration limits for the workers and outside the factory far below all limits for the inhabitants.
Compare this with a truck: a diesel motor emits about 4 kg of soot per ton of fuel. A full loaded truck uses approximately 33 kg of fuel per hour and emits 100 g of soot (into the smallest streets of towns). The carcinogenic potency of soot is in fact 13 times higher than of VCM, but the limits for soot outside factories are 4 times stricter. That means that a large chlorine-VCM-PVC factory is not more carcinogenic for the general public than about one truck...
There are always traces of monomers remaining in polymers. The possibility that the users will develop cancer by migration to food of these quantities is negligible in all cases.
The amount of VCM in PVC-bottles, used for water, is so low that, even if you drink two litres a day all your life and all VCM was migrating to the water, the total amount of VCM in a lifetime reaches the amount of VCM a PVC-worker may have during one working day. This gives a pure theoretical extra possibility of one to a hundred million to develop cancer.
Professor Maltoni of Bologna (Italy), who discovered the carcinogenity of VCM, did prove that PVC is neither as powder, nor as packaging a carcinogen. The latter was done in a mega experiment with 2000 rats, 1000 fed with water from glass bottles, 1000 fed with water from PVC bottles, were even PVC pellets were added. All rats were fed from before they were born until theirs death. All movements and sexual behaviour were controlled, and when they died, the cause of death was controlled too.
The results were, that there was no difference in behaviour, nor in average age and a non significant difference in the amount of cancer deaths, in fact the PVC-water drinkers had 1.9% less cancer!
For other packaging materials, the situation is not different: in all cases some very small quantities of possible carcinogens migrate to the packed food. For glass these are silicates and lead, for stoneware: lead and cadmium, for polyethylene (PE): ethylene and waxes, for polyethylene terephthalate (PET): acetaldehyde, etc., etc... In all cases the effect is negligible.
You are at level two of the Chlorophiles pages.
Created: March 9, 1996.
Last update: Februari 22, 1998.
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