# Is there a word for a toxin that is only toxic at certain levels? **URL:** \ **Category:** Factual Questions\ **Created:** [January 2, 2015, 3:30am UTC](https://boards.straightdope.com/t/is-there-a-word-for-a-toxin-that-is-only-toxic-at-certain-levels/708740 "2015-01-02T03:30:53Z")\ **Posts on this page:** 18\ **Page:** 1
**Author:** ![grude](https://avatars.discourse-cdn.com/v4/letter/g/e47774/32.png) [@grude](https://boards.straightdope.com/u/grude)\ **Post date:** [January 2, 2015, 3:30am UTC](https://boards.straightdope.com/t/is-there-a-word-for-a-toxin-that-is-only-toxic-at-certain-levels/708740/1 "2015-01-02T03:30:53Z")
Yea yea I know the Paracelsus quote about the dose making all poisons, but there are toxins that are toxic period in all amounts like cyanide and then there is stuff like morphine or nicotine where sub-lethal doses aren’t toxic in the sense of causing damage. Is there a term to differentiate absolute toxic substances that cause damage to the body at any dose and those that are only dangerous at a certain level but harmless below it? ---
**Author:** ![Joey\_P](https://avatars.discourse-cdn.com/v4/letter/j/919ad9/32.png) [@Joey\_P](https://boards.straightdope.com/u/Joey_P)\ **Post date:** [January 2, 2015, 3:38am UTC](https://boards.straightdope.com/t/is-there-a-word-for-a-toxin-that-is-only-toxic-at-certain-levels/708740/2 "2015-01-02T03:38:13Z")
I’m not sure about a term dosage that are harmless below a certain level and will harm you above it or a term for specific chemicals that will do that. However, “LD50” is the term for the dosage that you’re looking for. It’s the dosage at which about 50% of the subjects that take it will die (Lethal Dose 50%). For example, inhaling a little bit of a petroleum based substance (say, if you put Vaseline in you nose because it’s dry and cracked) and it probably won’t do anything, to much and you get a specific type of pneumonia (lipid pneumonia?). Is that what you’re looking for? Or are you looking for the name of something like Tylenol that if you take 250mg once a week, nothing’s going to happen. Take 5 grams every day and you’ll start damaging you’re liver. ---
**Author:** ![Ambivalid](https://avatars.discourse-cdn.com/v4/letter/a/a5b964/32.png) [@Ambivalid](https://boards.straightdope.com/u/Ambivalid)\ **Post date:** [January 2, 2015, 3:46am UTC](https://boards.straightdope.com/t/is-there-a-word-for-a-toxin-that-is-only-toxic-at-certain-levels/708740/3 "2015-01-02T03:46:04Z")
“Dose-specific” or “dose-dependent” toxicity. ---
**Author:** ![Exapno\_Mapcase](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/exapno_mapcase/32/1051_2.png) [@Exapno\_Mapcase](https://boards.straightdope.com/u/Exapno_Mapcase)\ **Post date:** [January 2, 2015, 3:55am UTC](https://boards.straightdope.com/t/is-there-a-word-for-a-toxin-that-is-only-toxic-at-certain-levels/708740/4 "2015-01-02T03:55:03Z")
I’m not understanding the OP. Of course cyanide will not cause damage in sufficiently low quantities, even if those quantities are much lower than others. There is a threshold for everything. Nothing is toxic in a single molecule. ---
**Author:** ![Telemark](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/telemark/32/372_2.png) [@Telemark](https://boards.straightdope.com/u/Telemark)\ **Post date:** [January 2, 2015, 3:56am UTC](https://boards.straightdope.com/t/is-there-a-word-for-a-toxin-that-is-only-toxic-at-certain-levels/708740/5 "2015-01-02T03:56:01Z")
> [@grude](#): > > there are toxins that are toxic period in all amounts like cyanide > **[Cyanide](https://en.wikipedia.org/wiki/Cyanide#Medical_uses)** > > In chemistry, cyanide (from Greek kyanos 'dark blue') is a chemical compound that contains a C≡N functional group. This group, known as the cyano group, consists of a carbon atom triple-bonded to a nitrogen atom. > In inorganic cyanides, the cyanide group is present as the cyanide anion −C≡N. This anion is extremely poisonous. Soluble salts such as sodium cyanide (NaCN) and potassium cyanide (KCN) are highly toxic. Hydrocyanic acid, also known as hydrogen cyanide, or HCN, is a highly volatile liq... > [@](#): > > The cyanide compound sodium nitroprusside is used mainly in clinical chemistry to measure urine ketone bodies mainly as a follow-up to diabetic patients. On occasion, it is used in emergency medical situations to produce a rapid decrease in blood pressure in humans; it is also used as a vasodilator in vascular research. ---
**Author:** ![grude](https://avatars.discourse-cdn.com/v4/letter/g/e47774/32.png) [@grude](https://boards.straightdope.com/u/grude)\ **Post date:** [January 2, 2015, 4:03am UTC](https://boards.straightdope.com/t/is-there-a-word-for-a-toxin-that-is-only-toxic-at-certain-levels/708740/6 "2015-01-02T04:03:53Z")
> [@Exapno\_Mapcase](#): > > I’m not understanding the OP. Of course cyanide will not cause damage in sufficiently low quantities, even if those quantities are much lower than others. There is a threshold for everything. Nothing is toxic in a single molecule. Well of course there is a level where there will be no effect at all, 1 part per billion etc. But wikipedia says even chronic exposure to sub-lethal levels causes damage to the body: > **[Cyanide poisoning](https://en.wikipedia.org/wiki/Cyanide_poisoning)** > > Cyanide poisoning is poisoning that results from exposure to any of a number of forms of cyanide. Early symptoms include headache, dizziness, fast heart rate, shortness of breath, and vomiting. This phase may then be followed by seizures, slow heart rate, low blood pressure, loss of consciousness, and cardiac arrest. Onset of symptoms usually occurs within a few minutes. Some survivors have long-term neurological problems. > Toxic cyanide-containing compounds include hydrogen cyanide gas and a n... > [@](#): > > Exposure to lower levels of cyanide over a long period (e.g., after use of cassava roots as a primary food source in tropical Africa) results in increased blood cyanide levels, which can result in weakness and a variety of symptoms, including permanent paralysis, nervous lesions,[4][5][6] hypothyroidism,[5] and miscarriages.[7][8] Other effects include mild liver and kidney damage What I meant is if there was a specific term for a toxin that doesn’t cause damage with sub-lethal exposure, but can be fatal at a certain level. ---
**Author:** ![grude](https://avatars.discourse-cdn.com/v4/letter/g/e47774/32.png) [@grude](https://boards.straightdope.com/u/grude)\ **Post date:** [January 2, 2015, 4:06am UTC](https://boards.straightdope.com/t/is-there-a-word-for-a-toxin-that-is-only-toxic-at-certain-levels/708740/7 "2015-01-02T04:06:40Z")
> [@Ambivalid](#): > > “Dose-specific” or “dose-dependent” toxicity. Thank you, this is what I was looking for. ---
**Author:** ![Smeghead](https://avatars.discourse-cdn.com/v4/letter/s/f1d935/32.png) [@Smeghead](https://boards.straightdope.com/u/Smeghead)\ **Post date:** [January 3, 2015, 2:37pm UTC](https://boards.straightdope.com/t/is-there-a-word-for-a-toxin-that-is-only-toxic-at-certain-levels/708740/8 "2015-01-03T14:37:28Z")
> [@grude](#): > > What I meant is if there was a specific term for a toxin that doesn’t cause damage with sub-lethal exposure, but can be fatal at a certain level. The term is “molecule”, because this description applies to literally every single molecule in existence. At a low enough dose, the most poisonous substance is harmless, and at a high enough dose, water can kill you. You are insisting on the existence of a category that simply does not exist. ---
**Author:** ![jz78817](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/jz78817/32/1028_2.png) [@jz78817](https://boards.straightdope.com/u/jz78817)\ **Post date:** [January 3, 2015, 2:42pm UTC](https://boards.straightdope.com/t/is-there-a-word-for-a-toxin-that-is-only-toxic-at-certain-levels/708740/9 "2015-01-03T14:42:56Z")
for drugs, there’s the “therapeutic index” which is the difference between an effective medical dose and a toxic dose. > **[Therapeutic index](https://en.wikipedia.org/wiki/Therapeutic_index)** > > The therapeutic index (TI; also referred to as therapeutic ratio) is a quantitative measurement of the relative safety of a drug. It is a comparison of the amount of a therapeutic agent that causes the therapeutic effect to the amount that causes toxicity. The related terms therapeutic window or safety window refer to a range of doses optimized between efficacy and toxicity, achieving the greatest therapeutic benefit without resulting in unacceptable side-effects or toxicity. > Classically, in cl... ---
**Author:** ![Chronos](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/chronos/32/134_2.png) [@Chronos](https://boards.straightdope.com/u/Chronos)\ **Post date:** [January 3, 2015, 3:12pm UTC](https://boards.straightdope.com/t/is-there-a-word-for-a-toxin-that-is-only-toxic-at-certain-levels/708740/10 "2015-01-03T15:12:22Z")
There’s sometimes a discussion of something called “threshold” in connection to harmful exposures. I’ve seen it most often in reference to radiation. The usual model of harm from radiation exposure is what’s called a “linear zero-threshold” model: That is, any amount of radiation is harmful, and twice the amount of radiation causes twice the amount of harm. Some argue, however, that there is some threshold value of radiation, such that radiation exposure below that level is completely harmless, or may even be beneficial. This makes a big difference for things like establishing acceptable levels of exposure in the workplace: If the threshold is zero, then prolonged exposure to even low levels is bad, and there’s some lifetime time limit to how long you should work in any given environment, but if there’s a nonzero threshold, then it’s safe to work in an environment indefinitely, if it’s always below that threshold. I don’t see why the same concept couldn’t be applied to chemical toxins. So what you’re looking for would be a toxin with a non-zero threshold. These certainly exist, since there are some substances which are toxic in high amounts but not only nontoxic but essential in low amounts. ---
**Author:** ![Canadjun](https://avatars.discourse-cdn.com/v4/letter/c/76d3ee/32.png) [@Canadjun](https://boards.straightdope.com/u/Canadjun)\ **Post date:** [January 3, 2015, 3:46pm UTC](https://boards.straightdope.com/t/is-there-a-word-for-a-toxin-that-is-only-toxic-at-certain-levels/708740/11 "2015-01-03T15:46:08Z")
IANAMD (or pharmacist), but if I understand the toxicity of Acetaminophen correctly it might be an example of what the OP has in mind. At low levels it is broken down harmlessly by the liver, but if you take too much the liver doesn’t produce enough of the proper enzymes to deal with it and you get toxic breakdown products. ---
**Author:** ![PastTense](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/pasttense/32/14550_2.png) [@PastTense](https://boards.straightdope.com/u/PastTense)\ **Post date:** [January 3, 2015, 4:07pm UTC](https://boards.straightdope.com/t/is-there-a-word-for-a-toxin-that-is-only-toxic-at-certain-levels/708740/12 "2015-01-03T16:07:31Z")
> [@grude](#): > > Well of course there is a level where there will be no effect at all, 1 part per billion etc. But wikipedia says even chronic exposure to sub-lethal levels causes damage to the body: So you are getting 5 units of a substance a day for 1000 days for a total of 5,000 units. While 5 units is sub-lethal, 5,000 units is not (a lot of substances are not immediately eliminated from the body–perhaps cyanide is one of them). ---
**Author:** ![Hector\_St\_Clare](https://avatars.discourse-cdn.com/v4/letter/h/b5ac83/32.png) [@Hector\_St\_Clare](https://boards.straightdope.com/u/Hector_St_Clare)\ **Post date:** [January 3, 2015, 5:22pm UTC](https://boards.straightdope.com/t/is-there-a-word-for-a-toxin-that-is-only-toxic-at-certain-levels/708740/13 "2015-01-03T17:22:29Z")
> [@grude](#): > > Yea yea I know the Paracelsus quote about the dose making all poisons, but there are toxins that are toxic period in all amounts like cyanide and then there is stuff like morphine or nicotine where sub-lethal doses aren’t toxic in the sense of causing damage. > > Is there a term to differentiate absolute toxic substances that cause damage to the body at any dose and those that are only dangerous at a certain level but harmless below it? Yes, it’s called a threshold response. (Incidentally, you can ingest cyanogenic foods in small quantities and be fine; I’ve done it before. Cassava, for example, or the seeds of many plants in the rose family like almonds, apricot pits, etc.). ---
**Author:** ![Smeghead](https://avatars.discourse-cdn.com/v4/letter/s/f1d935/32.png) [@Smeghead](https://boards.straightdope.com/u/Smeghead)\ **Post date:** [January 3, 2015, 5:23pm UTC](https://boards.straightdope.com/t/is-there-a-word-for-a-toxin-that-is-only-toxic-at-certain-levels/708740/14 "2015-01-03T17:23:12Z")
> [@Canadjun](#): > > IANAMD (or pharmacist), but if I understand the toxicity of Acetaminophen correctly it might be an example of what the OP has in mind. At low levels it is broken down harmlessly by the liver, but if you take too much the liver doesn’t produce enough of the proper enzymes to deal with it and you get toxic breakdown products. OK, fine. How is that different from every other substance in existence? ---
**Author:** ![Hector\_St\_Clare](https://avatars.discourse-cdn.com/v4/letter/h/b5ac83/32.png) [@Hector\_St\_Clare](https://boards.straightdope.com/u/Hector_St_Clare)\ **Post date:** [January 3, 2015, 5:34pm UTC](https://boards.straightdope.com/t/is-there-a-word-for-a-toxin-that-is-only-toxic-at-certain-levels/708740/15 "2015-01-03T17:34:20Z")
> [@grude](#): > > Well of course there is a level where there will be no effect at all, 1 part per billion etc. But wikipedia says even chronic exposure to sub-lethal levels causes damage to the body: > > [Cyanide poisoning - Wikipedia](http://en.wikipedia.org/wiki/Cyanide_poisoning) > > What I meant is if there was a specific term for a toxin that doesn’t cause damage with sub-lethal exposure, but can be fatal at a certain level. Many Africans (especially poor people in central Africa, who are the most likely to be growing/eating cassava) suffer from protein malnutrition. I’ve heard speculations that this aggravates the effect of low level cyanide toxictity- one way to detoxify cyanide in the body depends on using the sulfur present in sulfur-containing amino acids, and we derive these (in our diet) from protein consumption. On the other hand, a quick google search turns up a study indicating rats can adapt to low protein + cyanide diets by more efficiently recycling sulfur, so maybe not. [http://www.worldbank.org/html/cgiar/newsletter/Oct96/6cassava.html](http://www.worldbank.org/html/cgiar/newsletter/Oct96/6cassava.html) ---
**Author:** ![Rick](https://avatars.discourse-cdn.com/v4/letter/r/9f8e36/32.png) [@Rick](https://boards.straightdope.com/u/Rick)\ **Post date:** [January 3, 2015, 6:20pm UTC](https://boards.straightdope.com/t/is-there-a-word-for-a-toxin-that-is-only-toxic-at-certain-levels/708740/16 "2015-01-03T18:20:17Z")
> [@Smeghead](#): > > OK, fine. How is that different from every other substance in existence? Exactly. What isn’t lethal at a high enough concentration? ---
**Author:** ![Canadjun](https://avatars.discourse-cdn.com/v4/letter/c/76d3ee/32.png) [@Canadjun](https://boards.straightdope.com/u/Canadjun)\ **Post date:** [January 3, 2015, 8:22pm UTC](https://boards.straightdope.com/t/is-there-a-word-for-a-toxin-that-is-only-toxic-at-certain-levels/708740/17 "2015-01-03T20:22:13Z")
> [@Smeghead](#): > > OK, fine. How is that different from every other substance in existence? Because the response is non-linear. ---
**Author:** ![Smeghead](https://avatars.discourse-cdn.com/v4/letter/s/f1d935/32.png) [@Smeghead](https://boards.straightdope.com/u/Smeghead)\ **Post date:** [January 3, 2015, 9:22pm UTC](https://boards.straightdope.com/t/is-there-a-word-for-a-toxin-that-is-only-toxic-at-certain-levels/708740/18 "2015-01-03T21:22:05Z")
> [@Canadjun](#): > > Because the response is non-linear. So? The question was about a “toxin that is only toxic at certain levels”. The shape of the dose-response curve is irrelevant.