Wikipedia:Reference desk/Archives/Science/2018 July 11

= July 11 =

copper pitchers for storing drinking water
The alleged beneficent results of drinking water stored in copper pitchers have caused great demand for them and they are selling hot on Amazon India and other online stores. Numerous sites display pages describing such benefits. Are there chances of copper poisoning from drinking water stored in a copper pitcher? — Preceding unsigned comment added by 2405:204:D00C:7689:5D99:8D01:C88E:2E5D (talk) 16:28, 11 July 2018 (UTC)


 * This study says that storing drinking water in copper vessels has clear benefits in killing off bacteria in the water and that "Safety of leached copper does not appear to be an issue since studies have shown that the current WHO guideline of 2 mg Cu/L is safe ...., and the levels leached in the study were 1/20th of the permissible limits." Mikenorton (talk) 16:38, 11 July 2018 (UTC)


 * It's noted in hospitals the spread of infection has greatly increased after copper worktops (which killed bacteria) were replaced by plastic ones. 46.208.78.215 (talk) 18:41, 11 July 2018 (UTC)
 * Who says so? ←Baseball Bugs What's up, Doc? carrots→ 18:45, 11 July 2018 (UTC)
 * I don't know about any historic changes but Antimicrobial copper-alloy touch surfaces mentions clinical trials on new products. BTW we also have articles on Antimicrobial properties of copper and Copper alloys in aquaculture. Nil Einne (talk) 19:03, 11 July 2018 (UTC)
 * Copper is a poor choice, as it has toxicity risks. Although it also has antibacterial benefits, these are shared equally well (possibly better) by brass or monel fittings, which avoid the risks.
 * Copper is a risk depending on the water inside it. Hard water is fine, but something more acidic is a risk. Some contents - such as vinegar, pickles etc. involving acetic or lactic acid are downright dangerous. Andy Dingley (talk) 19:36, 11 July 2018 (UTC)
 * The above two articles for touch surfaces (which focuses a lot on in healthcare settings) and aquaculture at first glance seem to mostly deal with alloys given the titles. However if you check the touch surfaces one, sometimes it simply refers to copper. Most of the time it's unclear if this specifically means near pure copper or just a simplification of copper containing alloys. However they do mention C11000 foil which seems to be basically a form of pure copper (see Oxygen-free copper, [//alloys.copper.org/alloy/C11000]  although note as mentioned in those sources silver is counted as copper) is used for cladding bed rails in one hospital. The EPA also has a group which seems to cover pure copper group I 95.2% to 99.99% 82012-1 although of course it doesn't necessarily mean these products are used in hospitals. Note that from reading all these sources, it seems one complication is probably that from what I've seen in the earlier articles, is what you count as an alloy e.g. C11000 may be called a copper-alloy although from what I understand as said earlier it's basically pure copper. (While you don't have to have much of something else to reasonably be called an alloy e.g. steel, from the earlier sources it seems like C11000 often does not intentionally include anything else. In other words, other components are impurities rather than add to make an alloy.)  Anyway point being, while the reasons for the various choices isn't really mentioned at least with some healthcare surfaces I'm not sure whether it's true that copper alloys are always definitely better than what may reasonable be called copper. (And I'm also not convinced that the reason for choosing an alloy rather than simple copper is because of toxicity concerns.)  BTW that earlier article for touch surfaces mentions brass. However it does not mention monel and at least for EPA approved surfaces, it seems monel isn't suitable or at least hasn't yet been demonstrated as it says all of the registered ones have over 60% copper. They do have other Cupronickel alloys with a significantly higher percentage of copper e.g. C70600 [//alloys.copper.org/alloy/C70600] is one mentioned for the same hospital mentioned earlier.  Nil Einne (talk) 04:28, 12 July 2018 (UTC)


 * Here in Australia there has been some recent media hype about old "copper" plumbing fittings actually containing some lead, and hence being a potential source of lead poisoning. Being slightly technical, this is an area where I don't trust journalists in the mass media at the best of times. Most have no scientific training. But it struck me as possible. HiLo48 (talk) 23:44, 11 July 2018 (UTC)
 * The lead is more likely to come from the solder used to join the pipes. Make sure the water container is not soldered with lead containing solder. Graeme Bartlett (talk) 00:50, 12 July 2018 (UTC)
 * For greater clarity: read "lead-containing solder" or "solder containing lead". --76.69.47.228 (talk) 10:03, 12 July 2018 (UTC)
 * Ah yes, old solder. That makes sense. HiLo48 (talk) 07:54, 12 July 2018 (UTC)
 * European practice for some years now is that soldered joints for potable water need to be made with lead-free solder.
 * There's still plenty of short stubs of lead pipe around in old houses, usually the main water supply into the house. In most water conditions, this isn't a problem (the pipe interior is coated with a layer of deposited minerals). In places where the water will corrode the lead, more of such pipes have been replaced by now. To connect modern piping to old lead it's necessary to use a mechanical pipe fitting, not a soldered joint. The specific type of soldered joint used to connect to old lead requires a leaded solder, so can no longer be used on potable water (by the regulations), even though it's still permissible to leave the old lead pipe in use. Andy Dingley (talk) 10:03, 12 July 2018 (UTC)
 * Regulations will vary widely around the world. The OP is presumably in India. HiLo48 (talk) 10:06, 12 July 2018 (UTC)
 * Metallic copper probably has little or no toxicity. It's the copper salts, such as copper sulfate, that are toxic. But you'd need to ingest about 10 to 20 grams copper sulfate in order to die. Copper sulfate ingestion is relatively popular for committing suicide in India. Acidic foods such as vinegar, pickles etc. are already preserved by the acid, so there's no further benefit from putting them into copper vessels. --46.189.28.77 (talk) —Preceding undated comment added 10:32, 12 July 2018 (UTC)
 * Wilson's disease is an inherited genetic disorder in about 1 in 30,000 people in which copper builds up in the body, named after neurologist Samuel Alexander Kinnier Wilson 1878 - 1937. Some of the signs of copper sulphate poisoning after swallowing 1-12 grams include a metallic taste in the mouth, burning pain in the chest and abdomen, intense nausea, vomiting, diarrhea, headache, sweating, shock and discontinued urination leading to yellowing of the skin. DroneB (talk) 14:57, 12 July 2018 (UTC)

Doctors that refuse abortions
is there a name for a doctor who refuses to perform an abortion (in a country where abortion is legal), based on personal beliefs? The source I have checked calls it a "Conscientious objector", but I'm not sure if we should use that term in Wikipedia's voice, as it seems to be specific to the military. The source probably uses it simply because it conveys a similar idea.

NOTE: I'm not asking for help or medical advise about abortions, just a name. I'm writing an article about a proposed abortion law, and I want to make sure that I'm using the right terms. Cambalachero (talk) 19:07, 11 July 2018 (UTC)
 * Maybe see Hippocratic Oath. ←Baseball Bugs What's up, Doc? carrots→ 19:37, 11 July 2018 (UTC)
 * "Conscientious objection" does appear to be the commonly used term. Searching google for "Conscientious objection abortion" finds many relevant hits.- gadfium 20:07, 11 July 2018 (UTC)
 * "Conscientious objection" is the term used in the Abortion Act 1967, Section 4. See also, . --46.189.28.77 (talk) 20:14, 11 July 2018 (UTC)


 * And it's the term used by newspapers like The Guardian, but others refers to them as "abortion refuseniks" like The Spektator which is a misnomer, since refuseniks were the object of a denial, and not denied something actively themselves. --Doroletho (talk) 21:21, 11 July 2018 (UTC)


 * Perhaps we should update the article on Conscientious objector then, to include the non-military usage? Cambalachero (talk) 12:08, 12 July 2018 (UTC)


 * See Talk:Conscientious objector for previous discussion.  hydnjo (talk) 18:50, 12 July 2018 (UTC)

Japanese home appliances in a country split between a 50 Hz and 60 Hz power grid?
Japan, as a very rare exception (Brazil is another, don't know about others), has a power grid split between a 50 Hz and a 60 Hz area. Are there home appliances versions for each area? Are home appliances designed upfront with the idea in mind that they might be used in one or the other area (and therefore made to be tolerant of deviations)?--Doroletho (talk) 21:35, 11 July 2018 (UTC)
 * Virtually all this list of home appliances, consumer electronics and AC adapters tolerate the difference between 50 Hz and 60 Hz mains frequency with only a minor exception of older electric clocks, tape recorders and record players that employ synchronous motors whose rotation period is an integral number of AC cycles. West Japan uses 60 Hz and east Japan uses 50 Hz; on the boundary between the regions there are back-to-back HVDC sustations that convert the frequency. DroneB (talk) 22:48, 11 July 2018 (UTC)
 * Note that some home appliances which are affected by mains frequency e.g. clock radios have a 50/60 Hz switch. These devices don't generally have synchronous motors of course and developing a product with one which can easily cope with both frequencies is I imagine difficult enough that it is basically very rarely if ever done. Nil Einne (talk) 04:35, 12 July 2018 (UTC)
 * The one device which both depended upon frequency and couldn't easily be changed was the synchronous motor. I've some industrial cam timer switches here which run on 50Hz, but they're designed for the US market too. As their motors are standardised, it's a two-screw operation to swap the motors. Motor makers for these just make them in two forms, with the same final speed. I've even got old (unusued) spares of 60Hz US motors for them, taken off US-built equipment and swapped over when it was imported. The motors run fine on 50Hz, they just run slow.
 * My woodworking machinery (the large fixed stuff) runs on induction motors, rather than the brushed universal motors that a smaller or cheaper power tool tends to use. These are also related to line speed, so my machines here run more slowly than they would in the US. These motors run at fixed speeds (either a nominal 1500 / 1800 rpm or 3000 / 3600 rpm, depending on their 4 pole vs. 2 pole design, and the 50Hz / 60Hz line frequency), so they often have a pulley and belt drive to change the speed to what suits the machine. If I wanted to, I could change the pulley by a small amount to bring the speed back to the original speed - but it's rarely needed. Andy Dingley (talk) 10:16, 12 July 2018 (UTC)