From RationalWiki

is all-natural and therefore touching its tentacles will send you into a state of reconnection with the earth-spirit through horrible pain and then This box jellyfish is all-natural and therefore touching its tentacles will send you into a state of reconnection with the earth-spirit through horrible pain and then death in a few minutes.

An appeal to nature is a logical fallacy that occurs when something is assumed to be good because it is "natural" or bad because it is "unnatural".

The fallacy is, naturally, a naturalistic fallacy and thus an informal fallacy. The fallacy can be exemplified in one of three ways, with P1 and P2 being premisses and C being the conclusion that follows from them:

P1: A is natural (and thus good).

P2: B is not natural.

C: A is better than B.

P1: Natural is good.

P2: A is natural.

C: A is good.

P1: Synthetic/unnatural is bad.

P2: B is synthetic/unnatural.

C: B is bad.



Notably, the appeal to nature is often implicit in marketing, simply by using terms like "natural", "all natural", "natural goodness", "organic", "pesticide free", or "no artificial ingredients".

Deconstruction [ edit ]

Foxglove

Foxglove deconstructed: digoxin, the safer alternative

Appeal to nature is a fallacious argument, because the mere "naturalness" of something is unrelated to its positive or negative qualities – natural things can be bad or harmful (such as infant death and the jellyfish above), and unnatural things can be good (such as clothes, especially when you are in Siberia). Another problem is the distinction of what is "natural" and what is not, which can be murky: crude oil occurs naturally, but it's not something you'd like poured on seabirds or your garden. When does a product stop becoming natural? Any degree of human involvement? If that were the case, most of the fruits, vegetables, meat, seeds, and bread we eat don't qualify as natural as they've been selectively bred by humans for countless amounts of generations that they separated from their wild forms, yet no one ever rejects an apple in the organic grocery store as "unnatural". The word "natural" itself has no exact definition and can be used in multiple ways, thus allowing equivocation.

An excellent example of how tangled the concepts of "natural" and "non-natural", "desirable" and "undesirable" can become is the heart medication digoxin. It's a natural product of the foxglove plant (Digitalis spp.), which is quite poisonous as a plant. It is chemically extracted, or sometimes chemically synthesised, and dispensed in pill form because it relieves heart arrhythmias at therapeutic levels. However, at toxic levels it causes potentially fatal heart arrhythmias — and in fact is one of the plant toxins that makes foxglove so poisonous, and there is a fairly narrow window between therapeutic and toxic levels.[note 2] (One notable healthcare serial killer, Charles Cullen, used it as his killing agent of choice.) So is digoxin natural or non-natural? Desirable or undesirable?

As Harriet Hall noted:[4]

“ ” There is a reason pharmacology abandoned whole plant extracts in favor of isolated active ingredients. The amount of active ingredient in a plant can vary with factors like the variety, the geographic location, the weather, the season, the time of harvest, soil conditions, storage conditions, and the method of preparation. Foxglove contains a mixture of digitalis-type active ingredients but it is difficult to control the dosage. The therapeutic dose of digitalis is very close to the toxic dose. Pharmacologists succeeded in preparing a synthetic version: now the dosage can be controlled, the blood levels can be measured, and an antibody is even available to reverse the drug’s effects if needed.

In other words, whereas medicinal plants contain variable and unpredictable quantities of pharmacologically active substances, drugs are precisely dosed and you always know the exact quantity of active ingredient you are getting.

The problem with "natural living" [ edit ]

Appeals to nature are often encountered in advocacy for alternative medicine, food woo (organic food, vegetarianism, veganism,[note 3] raw foodism and paleo diet), general lifestyle woo, as well as in anti-industrial and anti-technological rhetoric, usually exhibiting themselves as something like:

This is obviously flawed, as in the following "reasoning": Arsenic is natural, and therefore it is better for you than the unnatural (hence bad) acetaminophen in Tylenol.[note 4] Of course, very few people actually take the appeal to nature to its logical conclusion, so they instead prefer to handwave the issue of toxic plants away with some non-reason that could perhaps be satirically described as "All plants are natural. But some plants are more natural than others."

In favor of the idea that it is better to "live naturally," some note that in earlier eras, when people "lived naturally", there were fewer cases of diseases commonly associated with the modern era, such as cancer or Alzheimer's. They argue that this is because of the lack of "synthetic" disease-causing substances in those times.[note 5] However, there is another, more likely, explanation. Cancer[5] and Alzheimer's are primarily diseases of old age. During the era of "natural living", people did not have particularly long lifespans, and so they did not, in general, live long enough to develop these diseases. Another common argument is that wild animals do not succumb to chronic illnesses,[note 6] in contrast to humans or their domesticated pets. This is not particularly convincing either, as this quote illustrates:

Quackwatch says: [6] For example, [Harvey Diamond] claims that "animals in nature are magnificently healthy in comparison to the health that we humans experience" but that pets and zoo animals develop "many of the problems of humans." The fact is that most animals in nature are infested with parasites and succumb to infections and malnutrition. It is only because predators usually kill sick animals that we don't see them stumbling across the plains and through the jungles. Perhaps it has never occurred to Harvey Diamond that the average American lives much longer than any mammal in the wild. The reason pets and zoo animals develop debilitating diseases is because they live much longer than their wild "cousins."

A study of over 50 species of animals published in 2016 showed that 84% of species studied live longer in zoos than in the wild, saying "zoos evidently offer protection against a number of relevant conditions like predation, intraspecific competition and diseases."[7]

The false dichotomy of natural and synthetic [ edit ]

An essential oil distillery for the distillation of sandalwood oil. Looks natural enough!

Usually, the word "natural" is used by alternative practitioners to mean "not synthetic", that is, a substance not formed from chemical reactions caused by human intervention. However, in practice, there may be confusion among alternative medicine supporters as to what constitutes a "natural" product. Many alternative medicine advocates will complain about "allopathy" using "chemicals" (meaning isolated substances) instead of plants, yet at the same time see no contradiction in using isolated active ingredients such as essential oils, glucosamine, glutamine, laetrile, chelation drugs, Tetrasil, Miracle Mineral Supplement, or any of the other countless non-herbal alternative medicines available, many of which are synthesized – like pharmaceuticals – and differ from conventional drugs only in that they are (usually) unapproved and unproven.[8] Grapefruit seed extract is criticized by some for consisting of unnatural chemicals, while others hail it as a natural remedy.[9][10][11] Some believers in the superiority of nature (some naturopaths, for instance) have no qualms using conventional pharmaceuticals, but arbitrarily classify some as being "good" and others as being "bad" for no apparent reason other than "I said so."[8][12][13] In other words, even believers in the appeal to nature may not agree on what the word "natural" is supposed to mean.[note 7]

This is pure, delicious 100% natural raspberry ketone, fresh from the plant!! Mmmmm…

This is toxic, synthetic p-Hydroxybenzyl acetone, a horrible pharmaceutical super-poison. You say you can't tell the difference? That's just because you're just too is toxic, synthetic-Hydroxybenzyl acetone, a horrible pharmaceutical super-poison. You say you can't tell the difference? That's just because you're just too close-minded and deep in the pockets of Big Pharma.

Furthermore, alternative medicine's obsession with "naturalness" relies on a premise with no scientific or rational backing.[note 8] If, as the appeal to nature posits, synthetic substances were lethal, and natural ones were perfectly safe (or at least much less harmful), then the differences between these alleged types of molecules would be enormous, and it would be the easiest thing in the world to distinguish between them. Similarly, it should be possible to identify the chemical reactions that can turn "natural" compounds into their "synthetic" counterparts (for instance, "natural" water into "synthetic" water). However, no evidence has been provided to support either claim.

This obsession can lead to some amusing incidents. One herb company chemically tested synthetic and natural raspberry ketones to determine whether it was possible to distinguish between the two.[14] They couldn't find any difference. Rather than conclude the synthetic and natural molecules were exactly the same, they decided not to sell the product at all, just in case.[14]

All drugs and synthesized compounds have their origins in nature. Supposedly, if the substances were brought together by humans, the product would be "synthetic", whereas if they were combined by a force of nature, like gravity or wind, the product would be "natural". But if reactants were brought together by a human as opposed to a mindless force or some animal other than Homo sapiens, why would this modify the nature of the particles, causing them to be "synthetic" and somehow inferior? Do humans have some negative aura that influences substances from a distance? And why doesn't this apply to homeopathy, which claims man-made homeopathic water is better than natural water?

There is a hidden premise that humans possess some taint that is transferred to anything they create, which is absent from anything created by absolutely any other species of living being in existence. Inherent in the premise is that humans are not part of nature. This is ridiculous in light of the fact that we are simply animals, who evolved in nature just as other animals did. The sole difference is our intelligence. And if the one who appeals to nature believes that applying intelligence to the things we create instead of doing it randomly is bad, then there's probably nothing you can say to them.

Broad and far-reaching conclusions about the fundamental nature of matter could be drawn based on scientific experiments conducted by (say) particle physicists; they could not be drawn based on such flimsy comparisons as those invoked in support of the appeal to nature (see below).

Testing and safety [ edit ]

When applied to medicine, the appeal to nature generally rejects rigorous scientific testing, focusing instead on the traditional use of particular substances for medical purposes (appeal to tradition). Counterexamples to the appeal to nature's insistence that "natural" traditional remedies must necessarily be safe include belladonna (Atropa belladonna), cigarettes, lead,[15][16] asbestos, comfrey, and tobacco,[note 9] among others. Nowadays these sorts of products have pretty much been banned, so, in general, only the harmless (and usually, though not always, useless) ones remain.[note 10]

The appeal to nature is often accompanied by a comparison of the side effects of some drug, and those of some herbal supplement, with the former being more numerous and serious than the latter. It is argued that this is because of some property inherent to "natural" objects that makes them safer than non-natural ones. This comparison is flawed, however.

Modern medical drugs are tested very thoroughly, by means of trials involving very large numbers of people and extending over long periods of time, with reporting systems in place to detect any possible (and potentially very rare) adverse effects after they have been launched on the market, leading to the well known lengthy lists of side effects. The use of large cohorts is necessary, as the frequency of some side effects can be as low as 1 per 100,000 patients.[19][20]

By contrast, herbal supplements have not undergone sufficient study necessary for regulatory approval, and side effects for herbal products are not as well monitored or recorded, so that any adverse effects may be ignored or just not reported. (Under-reporting of adverse effects is a prevalent issue for both drugs[21] and herbal supplements,[22] but likely more so in the case of the latter.[23][24]) The relative lack of study into the safety of herbal supplements poses a significant problem, as the experience- and anecdote-reliant approach favored by alternative practitioners is incapable of detecting side effects that are rare or manifest symptoms only after a long time,[note 11] and is often the real reason for the short side effect lists of herbal supplements. As Steven Novella noted in an article on birthwort:[25]

“ ” Common use may be enough to detect immediate or obvious effects, but not increased risk of developing disease over time. That requires careful epidemiology or specific clinical studies. We know about the risks of prescription drugs only because they are studied, and then tracked once they are on the market. Without similar study and tracking there is simply no way to know about the risks of herbal products.

Once these all natural remedies are put to the test, they are often proved to have side effects that can be just as bad as or even worse than conventional medicines.[26] As epidemiologist Geoffrey Kabat noted:[27]

“ ” What is essential to realize is that the effects of Aristolochia [birthwort] were identified only thanks to the large cluster of cases of kidney failure occurring in young women who had attended the same spa. It is much more likely that isolated cases will go unnoticed, as happened with

People failed to recognize the nephrotoxic effects of Aristolochia in spite of its use in many cultures worldwide over thousands of years. In an interview, [Arthur P.] Grollman explained why: “The reason, of course, is quite simple. It's painless, and the damage happens much later, so you don’t put together the fact that you took this medicine and four years later, you have kidney failure. It's been part of Ayurvedic, European, Chinese, and South American medicine for centuries. All of the great civilizations have used it. And not one reported its toxicity until the Belgians did 20 years ago. There are certain things that tradition can't tell you." What is essential to realize is that the effects of[birthwort] were identified only thanks to the large cluster of cases of kidney failure occurring in young women who had attended the same spa. It is much more likely that isolated cases will go unnoticed, as happened with ephedra , and it could take years to identify a common cause.People failed to recognize the nephrotoxic effects ofin spite of its use in many cultures worldwide over thousands of years. In an interview, [Arthur P.] Grollman explained why: “The reason, of course, is quite simple. It's painless, and the damage happens much later, so you don’t put together the fact that you took this medicine and four years later, you have kidney failure. It's been part of Ayurvedic, European, Chinese, and South American medicine for centuries. All of the great civilizations have used it. And not one reported its toxicity until the Belgians did 20 years ago. There are certain things that tradition can't tell you."

In addition, a side effect profile of a given quantity of a herb and that of the same quantity of a drug derived from it are not necessarily comparable. A drug is a pure active ingredient, whereas a plant may contain hundreds of different chemicals, of which only a few may actually have medicinal effects. As Steven Novella noted, "The fact that individual chemicals are not purified and given in precise amounts does not mean they are not pharmacologically active chemicals – it just means that when taking an herbal remedy you are getting a mixture of many chemicals in unknown doses."[25] It would not be particularly surprising for a given quantity of a drug to be stronger (and hence have more or more severe side effects) than the same quantity of the plant it is derived from; the drug would contain more active ingredient per weight than the plant. Some plants may indeed, for this reason, be safer than their pharmaceutical derivatives, but this does not imply that they are also more (or even just as) effective, and this certainly could not be extended into a general rule applicable to all, or even most, plants.[note 12]

It is often claimed that herbal medicine "is food, so it must be safe." Of course, just because some plants are food does not mean they all are. Many, if not most, of the herbs used in herbal supplements sold for therapeutic purposes have no nutritional value, and are taken solely for their pharmacological effects on the body. To quote Steven Novella:[25]

“ ” With food and food ingredients the With food and food ingredients the FDA does not require evidence of safety if the ingredient is generally recognized as safe. This might make sense when referring to foods that have been eaten by humans for a long time. Although the logic is still dubious, it's just practical – the FDA could not take upon itself the task of proving that every food eaten by humans has no significant negative health consequences. It is more a recognition of practicality than reality. […] Herbal remedies are drugs, plain and simple. They contain chemicals that are ingested on a regular basis for their pharmacological effects. The fact that they derive from plants is irrelevant.

Not to mention that many natural foods are quite unhealthy and can have detrimental effects on the human body.

Politics [ edit ]

The appeal to nature is also a tool for criticizing advancements in technology or behaviors that are perceived to undermine cultural norms. A common example of this appeal is to claim that homosexuality is immoral because it is unnatural. The logic being that since sexual reproduction involves intercourse between a single male and a single female, any deviation from this interaction must be going against our natural design as humans. This argument is fallacious if for no other reason than the many examples of homosexuality found in animals.[28]

Similarly, scientific advancements that allow people to overcome normal biological constraints may be disparaged for being unnatural, often by claiming that scientists are attempting to "play God". Cloning and gene editing, for example, have been regarded as unethical for interfering with the natural order of human life, or creating life outside of the process defined by nature.[29][30]

Of course, these appeals fall into the same trap as the medical examples above. The exact definition of "natural" in these cases can be nebulous, or else can ignore clear examples that contradict the argument. In the case of homosexuality, for example, various non-human animals also exhibit homosexual behavior, raising the question of how this behavior can be unnatural if it occurs in nature.[31] Trying to further define "natural behavior" in terms of normal sexual behavior would end up being circular reasoning.

Likewise, accusations of science or technology playing God and going too far by messing with natural processes fails to define what the "natural process" is, and why human intervention of any form is "unnatural". Other advancements, such as farming and construction, involve configuring materials to create products that would not otherwise occur in nature, yet no one accuses farmers or architects of disrupting the natural order. The only real difference is that the advancements being criticized now are ones that have not yet become commonplace, and therefore we do not currently take for granted.[32]

Examples [ edit ]

There is a vast range of natural things that are bad and frequently fatal for humans. These include naturally-found chemicals such as cyanide; an enormous number of diseases including smallpox; a list of toxic plants too long to mention and, for that matter, animals such as lions, tigers and bears.

In some cases people have died from excessively restrictive "natural" diets, such as "Kokovore" August Engelhardt and several cases of young children who were subjected to vegan diets. On the other hand, fertilisers, many modern medicines, hygiene, and semiconductor-grade silicon do not occur naturally, but they have great benefit to humans individually and in societies.

Individual foods [ edit ]

"Natural" meats packed inside unnatural plastic packaging for your hygienic pleasure

Proponents of various forms of food and diet woo use the appeal to nature to stress what kinds of food we should be putting into our body to reduce toxins, become better attuned with our ancestors, or avoid oppression from shady cabals like Big Dairy. Adherents of raw foodism, for example, argue that the process of cooking food creates harmful toxins that are not present naturally, and of course any existing bacteria can't be that dangerous. Similarly, construction and development of paleo diet (often referred to as the "caveman diet") has often centered around foods consumed by peoples that live more "natural" lives, or foods that have existed for tens of thousands of years and thus must be perfectly healthy. Genetically modified food is also attacked for being "unnatural," ignoring that the basic science behind genetic modification has been put to use in farming practices for millennia. In the U.S., the food industry, aided by the Food and Drug Administration's lack of regulation on the term, has also capitalized on the "all natural" craze. For instance, we have "all-natural" Sprite, which uses high-fructose corn syrup (HFCS), produced by a centrifuge. However, this still raises the question as to when something becomes or ceases to be "natural". Using the above example, all of the materials used to make HFCS do in fact come from raw materials. Putting a line in the sand as to using a centrifuge is arbitrary at best (e.g., how is the centrifuge less natural than distillery used to make essential oils?).

Hidden in the premise of the appeal is that any food found in nature must be safe. However, quite a few foods are actually naturally toxic, even in unadulterated or uncontaminated form. This is because there is a war on for survival, and all plants contain natural pesticides that they use to deter herbivory. Plant domestication has generally reduced the natural pesticide content of foodstuffs, but it hasn't fully eliminated it (and not all of it needs to go away, per se, or we'd have vulnerable crops instead). Some animals are also toxic to eat, including some fish, birds, and amphibians. In this section are foods that are sometimes toxic to consume, not foods that merely contain toxins (as almost all plant foods contain toxins naturally). See also "Naturally Occurring Food Toxins" for a review of hazardous foods.[33]

Ackee [ edit ]

Ripe ackee

Ackee (Blighia sapida, Sapindaceae family) is a popular Jamaican fruit that was originally imported from Africa, where it is also eaten. It causes Jamaican vomiting sickness because of the natural presence of hypoglycin A in the fruits. When the fruits are fully ripe, hypoglycin A is present at only <0.1 ppm but unripe fruits can contain 1000 ppm, which can be lethal.[34]

Beans [ edit ]

Aside from being a magical fruit, many varieties of beans are actually toxic and contain high amounts of phytohaemagglutinin. Luckily, this toxin breaks down via boiling.

Favism is a disease caused by among other things, consumption of fava beans (Vicia faba). The disease only affects people with a specific genetic predisposition that is common in people of Mediterranean and African origin. Symptoms include jaundice, hemolytic crises, diabetic ketoacidosis, and acute kidney failure.

Cassava [ edit ]

Disease resistant cassava plants: extra high in cyanide

Cassava (Manihot esculenta), also known as yuca or manioc is a starchy root that is a dietary staple in some parts of the world. It is also naturally high in cyanide. When not properly prepared, it has caused intoxication, goiters, ataxia, partial paralysis, and death.[35] The bitterer varieties (higher in cyanide) are often preferred by farmers because they are better pest deterrents.[36]

Cycad [ edit ]

In Guam, cycad (Cycas micronesica) seeds were traditionally made into flour and eaten as a dietary staple. Cycads in Guam are symbiotic with a photosynthetic bacteria that enables the plant to produce the toxin beta-Methylamino-L-alanine (BMAA). Chamorro people of Guam and Rota islands eating a traditional diet were 50-100 times more likely to have amyotrophic lateral sclerosis/parkinsonism-dementia complex (caused by BMAA) than other people.[37][38]

Elderberry [ edit ]

Blackberry and elderberry jam

Elderberry (Sambucus spp.) is a genus of plants, nearly all of which are high in cyanides. If not properly prepared (fully ripe and cooked) elderberry juice can cause sickness.[39]

Fish [ edit ]

Fugu, waiting for a chef who hopefully knows where the poison is. , waiting for a chef who hopefully knows where the poison is.

Predator species of reef fish can bioaccumulate ciguatera toxin produced by dinoflagellates. Symptoms include nausea, vomiting, and diarrhea, headaches, muscle aches, paresthesia, numbness, ataxia, vertigo, and hallucinations.[40][41] Ciguatera cannot be eliminated by normal cooking.[40]

Puffer fish (family Tetraodontidae) are considered a delicacy in Japan where it is known as fugu (河豚). Puffer fish naturally contain tetrodotoxin, which may originate from their intestinal bacteria.[42] Fugu chefs are specially trained to remove enough parts of the fish to prevent death but to sometimes induce euphoric feelings from intoxication, but deaths still occur on occasion.[43]

Escolar (Lepidocybium flavobrunneum) and oilfish (Ruvettus pretiosus) (both in family Gempylidae) are high in oil content, but are also high in indigestible wax esters which can cause oily diarrhea, nausea, headache, and vomiting.[44] Italy and Japan have banned the sale of these two fish, and other countries have put restrictions on their sale.[45]

Lychee [ edit ]

Lychee fruits

Lychee (Litchi chinensis, Sapindaceae family) is native to China and is mainly grown in India and China. Outbreaks of noninflammatory encephalopathy in India and Vietnam have been linked to consumption of lychee, with symptoms similar to Jamaican vomiting sickness.[46][47] Lychee sickness is also due to the presence of hypoglycin as well as a similar toxin, methylenecyclopropyl glycine, in the fruit.[47]

Mushrooms [ edit ]

A. hondensis could be poisonous depending on who you are could be poisonous depending on who you are

There are many species of mushrooms, with widely ranging levels of toxicity. They range from the almost always fatal (not food, but sometimes mistaken for food) to the sometimes sickening (wild food) to the domesticated (e.g., the common mushroom Agaricus bisporus). Some wild species only sicken some people, e.g., A. hondensis,[48] whereas others are often deadly even though they are delicious (Amanita phalloides).[49] There are many erroneous folk beliefs about whether mushrooms are safe, but only science-based methods are reliable.[50][51]

Pokeweed [ edit ]

Pokeweed (Phytolacca americana) has traditionally been used as both a food and as an herbal medicine in the United States, particularly in southern Appalachia. Pokeweed contains several toxins in high levels, including saponins and saponin-like chemicals.[52][53][54]

Potato [ edit ]

Green potatoes

Potatoes (Solanum tuberosum), family Solanaceae) which have turned green from Sun exposure or age have increased levels of solanine. Potato poisoning from excessive solanine can cause death, vomiting, diarrhea, abdominal pain and, in severe cases, depression of the central nervous system.[55] Cooking potatoes does not eliminate solanine levels.[55] Cases of potato poisoning have been reported in 1899, 1918, 1922, 1925, 1948, 1952 and 1983.[55]

The fruit of the potato is also packed with solanine; there is a reason you didn't know potatoes had fruit.

Wheat [ edit ]

Wheat and other food crops in the Balkans have been shown to bioaccumulate the nephrotoxin aristolochic acid that is released from Aristolochia plants. These crops in the Balkans have been shown to be responsible for Balkan endemic nephropathy.[56]

Carcinogens [ edit ]

Dermal melanoma: mainly caused by natural sun exposure

The International Agency for Research on Cancer (IARC) regularly evaluates the evidence for whether various agents (chemicals, activities and exposure situations) as to whether the agents are likely to be human carcinogens. The highest level of evidence, Group 1, is regarded as definitively "Carcinogenic to humans", usually based upon strong epidemiological evidence but also with supporting evidence from animal and mechanistic studies. As of December 2016, there have been 116 evaluations for Group 1 carcinogens.[57] Of these 116, 67 (58%) could be regarded as being from naturally-occurring chemicals, activities, or exposure situations.[58]

This is an imperfect count of natural carcinogens, but it nonetheless shows that natural is not inherently "good", and also that synthetic is not inherently "bad". The latter is the case because there are several synthetic cancer treatment drugs, which are effective in treating cancer but also carry a usually smaller risk for causing cancer. There is some redundancy in the table, e.g., there are several types of radiation exposures that have separate evaluations even though the mechanism of carcinogenesis is basically the same, which could be considered a type of double counting. The question of what is and is not natural is not always clear-cut, e.g., tanning beds seem synthetic but the mechanism of carcinogenesis is the same as that of natural Sun exposure.

IARC Human Carcinogen Exposure Natural/Synthetic Acetaldehyde associated with consumption of alcoholic beverages Beverage Natural Acheson process, occupational exposure associated with Occupational Synthetic Acid mists, strong inorganic Occupational Synthetic Aflatoxins Food Natural Alcoholic beverages Beverage Natural Aluminium production Occupational Synthetic 4-Aminobiphenyl Occupational/Tobacco Natural Areca nut [a.k.a., betel nut, Areca catechu] Food/Herbal Medicine Natural Aristolochic acid Herbal Medicine Natural Aristolochic acid, plants containing [Aristolochia genus] Herbal Medicine Natural Arsenic and inorganic arsenic compounds Occupational/Beverage Natural Asbestos (all forms) Occupational/Air Natural Auramine production Occupational Synthetic Benzene Various Natural Benzidine Occupational Natural Benzidine, dyes metabolized to Occupational Natural Benzo[a]pyrene Various Natural Beryllium and beryllium compounds Occupational Natural Betel quid with tobacco Drug/tobacco Natural Betel quid without tobacco Drug Natural Bis(chloromethyl)ether; chloromethyl methyl ether Occupational Synthetic Busulfan Cancer treatment Synthetic 1,3-Butadiene Occupational Synthetic Cadmium and cadmium compounds Occupational/Air Natural Chlorambucil Cancer treatment Synthetic Chlornaphazine Cancer treatment Synthetic Chromium (VI) compounds Occupational/Air Natural Clonorchis sinensis (infection with) Infection Natural Coal, indoor emissions from household combustion of Heating Natural Coal gasification Occupational Natural Coal-tar distillation Occupational Synthetic Coal-tar pitch Occupational Natural Coke production Occupational Synthetic Cyclophosphamide Cancer treatment Synthetic 1,2-Dichloropropane Occupational Synthetic Diethylstilbestrol Drug Synthetic Engine exhaust, diesel Air Synthetic Epstein-Barr virus Infection Natural Erionite Occupational/Air Natural Estrogen-only menopausal therapy Drug Natural Estrogen therapy, postmenopausal Drug Natural Estrogen-progestogen menopausal therapy Drug Natural Estrogen-progestogen oral contraceptives Drug Natural Ethanol in alcoholic beverages Beverage Natural Ethylene oxide Occupational Synthetic Etoposide Cancer treatment Semi-synthetic Etoposide in combination with cisplatin and bleomycin Cancer treatment Synthetic Fission products, including strontium-90 Occupational, etc. Synthetic Fluoro-edenite fibrous amphibole Occupational Natural Formaldehyde Various Natural Haematite mining Occupational Natural Helicobacter pylori Infection Natural Hepatitis B virus (chronic infection with) Infection Natural Hepatitis C virus (chronic infection with) Infection Natural Human immunodeficiency virus type 1 (infection with) Infection Natural Human papillomavirus types 16, 18, 31, 33, 35, 39, 45, 51, 52, 56, 58, 59 Infection Natural Human T-cell lymphotropic virus type I Infection Natural Ionizing radiation (all types) Various Natural Iron and steel founding (occupational exposure during) Occupational Synthetic Isopropyl alcohol manufacture using strong acids Occupational Synthetic Kaposi sarcoma herpesvirus Infection Natural Leather dust Occupational Synthetic Lindane Occupational Synthetic Magenta production Occupational Synthetic Melphalan Cancer treatment Synthetic Methoxsalen (8-methoxypsoralen) plus ultraviolet A radiation Drug Natural Methyl-CCNU Cancer treatment Synthetic 4,4'-Methylenebis(2-chloroaniline) (MOCA) Occupational Synthetic Mineral oils, untreated or mildly treated Occupational/Food Natural MOPP and other combined chemotherapy including alkylating agents Cancer treatment Synthetic 2-Naphthylamine Occupational/Tobacco Natural Neutron radiation Various Natural Nickel compounds Occupational/Air Natural N'-Nitrosonornicotine (NNN) and 4-(N- Nitrosomethylamino)-1-(3-pyridyl)-1-butanone (NNK) Tobacco Natural Opisthorchis viverrini (infection with) Infection Natural Outdoor air pollution Air Synthetic Outdoor air pollution, particulate matter in Air Synthetic Painter (occupational exposure as a) Occupational Synthetic 3,4,5,3’,4’-Pentachlorobiphenyl (PCB-126) Various Synthetic 2,3,4,7,8-Pentachlorodibenzofuran Various Synthetic Phenacetin Drug Synthetic Phenacetin, analgesic mixtures containing Drug Synthetic Phosphorus-32, as phosphate Drug Natural Plutonium Nuclear energy/Nuclear weapons Synthetic Polychlorinated biphenyls Various Synthetic Polychlorinated biphenyls (PCBs 77, 81, 105, 114, 118, 123, 126, 156, 157, 167, 169, 189) Various Synthetic Radioiodines, including iodine-131 Various Natural Radionuclides, alpha-particle-emitting, internally deposited Various Natural Radionuclides, beta-particle-emitting, internally deposited Various Natural Radium-224 and its decay products Various Natural Radium-226 and its decay products Various Natural Radon-222 and its decay products Various Natural Rubber manufacturing industry Occupational Synthetic Salted fish, Chinese-style Food Natural Schistosoma haematobium (infection with) Infection Natural Semustine Cancer treatment Synthetic Shale oils Occupational Natural Silica dust, crystalline, in the form of quartz or cristobalite Occupational Natural Solar radiation Various Natural Soot (as found in occupational exposure of chimney sweeps) Occupational Natural Sulfur mustard Chemical warfare Synthetic Tamoxifen Cancer treatment Synthetic 2,3,7,8-Tetrachlorodibenzo-para-dioxin Various Synthetic Thiotepa Cancer treatment Synthetic Thorium-232 and its decay products Various Natural Tobacco, smokeless Tobacco Natural Tobacco smoke, second-hand Tobacco Natural Tobacco smoking Tobacco Natural ortho-Toluidine Occupational Synthetic Treosulfan Cancer treatment Synthetic Trichloroethylene Various Synthetic Ultraviolet radiation (wavelengths 100-400 nm, encompassing UVA, UVB, and UVC) Various Natural Ultraviolet-emitting tanning devices Tanning devices Synthetic Vinyl chloride Occupational Synthetic Wood dust Occupational/Air Natural X- and Gamma-Radiation Various Natural

In an analysis of chemicals tested for carcinogenicity in rodents at high doses, 57% of naturally-occurring chemicals were found to be carcinogenic vs. 60% of synthetic chemicals.[59]

See also [ edit ]

Notes [ edit ]