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Lead

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Lead, symbol Pb, known as plumbum in Latin, is a heavy metal. It is element number 82 in the Periodic Table.[1] It is the heaviest element that has stable isotopes, making it the endpoint of the radioactive decay of many of the heavier elements such as uranium and radium.[2][3] It has many uses due to its high density, resistance to corrosion, and malleability. Lead isn't the only element that has these properties, in fact, many of the elements around it in the Periodic Table have similar properties, with some even outcompeting lead in some of these regards. However, lead has one significant advantage over these other metals: it's cheap. As of 2018, one metric ton of tungsten, the most common substitute, cost $30,300,[4] while gold cost a whopping 40 million dollars per metric ton.[5][note 1] Lead, on the other hand, was only a meager $2,240 per metric ton.[6] However, this cheapness comes at a significant price: lead is severely toxic. Ingesting it causes numerous neurological problems,[7] hence it has slowly been removed from almost everything it used to be used in.[8] European Union ROHS (Restriction of Hazardous Substances Directive) standards now prohibit its use entirely,[9] meaning that the Chinese have to put all their lead in US-bound toys, toothpaste and Soylent.

Toxicity[edit]

Inorganic lead compounds as well as lead subacetate, lead chromate, and lead phosphate are carcinogenic in animal studies; there is insufficient information to evaluate lead carcinogenicity in humans.[10] Lead can cause a wide range of health problems in humans from both acute exposure (e.g., constipation, memory loss, loss of appetite) and chronic exposure (e.g., forgetfulness, depression, high blood pressure, heart disease, kidney disease and infertility).[11] In children, it has been estimated to cause 600,000 new cases of intellectual disabilities each year worldwide.[12] Worldwide, it is estimated to cause 143,000 deaths per year.[12] Lead exposure has also been linked to higher rates of criminality[13] and reduced IQ.[14]

Various writers in ancient Rome considered lead to be a poison, either explicitly or implicitly, including Pliny the Elder, Dioscurides, Galen, Celsus and Vitruvius (80–70 BCE); it was Vitruvius who described lead plumbing specifically to be unhealthy.[15] The epidemics of saturnine colic (17th century) and Devonshire colic both lasted for decades, the latter of which was only recognized by George Baker in 1767 as being caused by lead ingestion some 70 years after it was first recognized as a disease.[16] Lead use and concomitant poisoning of lead workers increased mark Industrial Revolution.[16] The toxic effects of lead in workers were recognized by science in the 19th century, and the first laws regulating lead exposure in the workplace came about in the UK in the 1870s-1880s.[16] The first documented poisoning from lead paint ingestion was in 1914.[17]:11

"Lead" in pencils is not the metal lead but in fact a combination of non-toxic graphite (a form of carbon) with a binder of non-toxic clay.

Kennedy Krieger Institute[edit]

A map that compares the areas of Baltimore that have problems with lead paint to the areas that are predominantly inhabited by black people (largely as a result of redlining), showing that this is a persistent systemic problem to this day.

The Kennedy Krieger InstituteWikipedia (KKI) has been a pioneer in the area of research into and treatment of lead poisoning since the 1940s.[17]:9 In 1991, KKI embarked upon what would become a controversial study, known as the Baltimore Lead Paint StudyWikipedia, into the health effects of lead and into the effectiveness of lower-cost lead abatement techniques. The study recruited low-income families who were mostly African American to live in lead-contaminated properties and partially-abated properties using different techniques. The study included 140 children in 107 properties. After the study was completed, many of the children had permanent neurological damage. A class action lawsuit was filed against KKI in 2001 and has not been resolved as of 2018. Since the study did not benefit the children who were the subjects of the study, but theoretically would have benefited other low-income children in lead contaminated housing, it has been argued by the plaintiffs that the study violated ethical research standards, including adequate informed consent.[17]:168-231 The court in the class action suit went so far as to argue that the KKI study presented "similar problems as those in the Tuskegee Syphilis Study… the intentional exposure of soldiers to radiation in the 1940s and 50s, the test involving the exposure of Navajo miners to radiation… and the secret administration of LSD to soldiers by the CIA and the army in the 1950s and 60s."[17]:2 The court also said that the study defied aspects of the Nuremberg Code.Wikipedia[17]:2

Lead industry[edit]

National Lead Company, advertising the use of lead in children's toys in 1923

By the 1920s, lead in paint became widespread in the US. This was not by necessity but for profit because relatively safe zinc-based paints were widely available in the 1920s and titanium-based paints were available by the 1930s.[17]:8 Starting at this point in time, lead-based paint became the primary vector for lead poisoning in children, with lead included in a myriad of toys as well as lead-painted home walls.[17]:8 In 1928, the Lead Industries Association (LIA) was formed to lobby for use of lead pipes in plumbing among plumbers and plumbing code writers.[18] The LIA also downplayed the hazards of lead.[17]:29 In 1949, Maryland passed the first law to prevent lead poisoning in children, the Toxic Finishes Law.[17]:31 This had become necessary because Baltimore had one of the highest rates of poisoning.[17]:6 The LIA lobbied Maryland officials and had the law repealed in 1950.[17]:32 the LIA had argued that the law was an unnecessary burden on lead-based manufacturers, and that the best means of minimizing lead exposure was educating parents.[17]:32 In 1950, the LIA also knew that lead exposure was a growing problem for the industry and had a growing collection of privately-held research into lead hazards.[17]:32-33 The lead industry has in fact been engaging in a coverup, a form of denialism, by simultaneously privately researching and understanding the hazards of lead while publicly trying to minimize the perception of their hazards.[17]:29-33

Sources of exposure[edit]

In gasoline[edit]

Tetraethyllead chemical structure

Originally, car engines had to be started by hand while turning a crank to begin ignition. This was a dangerous process, and when Byron Carter, who was a friend of the owner of Cadillac, was killed when the crank backfired and hit him in the face, this inspired car companies to begin using electric starter motors instead.[19] These motors had a problem, however: the fuel explosions, which are typically controlled, began happening in irregular intervals in a process known as "knocking". This caused the cars to be loud and could result in damage to the engine.[20] In the 1920s, inventor Thomas Midgley Jr.Wikipedia was tasked with finding an additive to gasoline that would reduce engine knocking, and despite knowing it was poisonous, he gave the approval to use the lead compound tetraethyllead.Wikipedia[21][note 2] The compound was used as an additive to gasoline from the 1920s until the 1980s phase-out in the United States, and today, ethanol is the most commonly used antiknock agent.[22] It was phased out in other countries at different times, but by 2021, it was finally no longer used in cars and trucks, with Algeria being the last to use it.[23] Its contribution to pollution of the air and soil in cities and around motorways, combined with its incompatibility with catalytic converters, caused it to be phased out. Leaded fuels are still used by racecars and piston-engine aircraft as it reduces engine knock and increases the octane rating, though people are trying to find alternatives to these as well.[24]

In paint[edit]

Spreading the toxicity around

Lead was used in paint since the time of the ancient Romans (4th century BCE), and the process of making the paint was described by Pliny the Elder. When lead is added to paint, it is more durable, dries faster, and lasts a long time. In the United States, it has been banned from household paints since 1978 due to its toxicity, but is still found in many areas of the U.S., especially in lower-income urban areas. Lead paint is often considered a racial justice issue, as there is strong evidence that lead paint affects black and Latino children at far higher rates, mainly due to the areas that still have problems with lead paint having been the targets of redlining in the past, and is a good counter to people who believe that systemic racism has no effects in the U.S. today.[25]

For another kind of lead paint, galena or lead sulfide was frequently used as a black pigment even up to the nineteenth century times. It was only one of many toxic pigments that were used at the time, with others including cinnabar/vermillion (mercury sulfide), cadmium yellow (cadmium sulfide), and Paris green (copper acetoarsenite).[26]

In plumbing[edit]

The word plumbing is derived from plumbum, the Latin word for lead, as the Romans made their pipes out of lead. Lead was used for plumbing for most of human history, with the U.S. only banning new lead pipes from being developed in 1986. An estimated 15 to 22 million Americans still drink water that goes through lead pipes,[27] and about a quarter of households in the EU still have lead pipes.[28] While new lead plumbing is not produced anymore (at least not in the U.S. or EU), many pipes made of lead are still in the ground or old houses. While this usually does not cause problems due to a protective coating on the inside of the pipes, if the water is corrosive enough to destroy the coating, lead may leach into the water causing tremendous long term damage to all who drink the water. One of the most famous examples of this happening was in Flint, Michigan, after the water source was switched from Detroit's system to the Flint River in an attempt to save money without anyone from the government testing the notoriously polluted water. The result was an attempted coverup on the part of the state government and dangerous levels of not only lead but also Legionnaires’ disease and carcinogenic TTHMs in the water,[29] and Michigan's at-the-time governor Rick Snyder was charged in 2021 for his role in the crisis.[30] Although some studies have suggested ways to make lead pipes safer by using electricity to attach phosphates to the lead,[31] most people understandably would prefer all of the lead pipes to be replaced.[32]

In cosmetics[edit]

A display including cosmetics with lead content in 1934

The ancient eye cosmetic known as kohlWikipedia is still used in some parts of the world. It is sometimes made with stibnite (Sb2S3), and sometimes made with lead (galena or PbS). Kohl that is not made from lead is usually considered of lower quality. Composition of lead-based kohl can be as high as 84%.[33][34] A 2009 review article concluded that cosmetic use of kohl is "likely to be more theoretical rather than a practical health hazard."[35] That's not to say that there are no dangers, children have been known to consume kohl, which does raise blood lead levels, and putting it over an open wound is dangerous. Lead has also been found in lipsticks, usually as a result of contamination rather than intentionally being put in them, but most lipsticks have been found to contain lead at below the FDA's limit of 10 ppm, though sometimes a more dangerous one will surface.[36]

In hunting and fishing[edit]

Lead's malleability and density make it good for making bullets, and it was also used to make fishing weights. However, recent studies have shown these to be very toxic to wildlife, especially to birds of prey which will often ingest lead bullets in carcasses left by hunters and fish that have swallowed fishing weights.[37][38] Lead is increasingly being phased out of bullets and replaced by nontoxic metals like tungsten.[39] Sadly, this issue has been met with much resistance and denialism, mainly from gun nuts, which is why efforts to change have been slow.[40] Barack Obama tried to ban lead bullets from federal wildlife refuges, but this was undone by the Donald Trump administration.[41]

Other uses[edit]

Most stained glass, like this piece by Louis Comfort Tiffany,Wikipedia is leaded.

Quite possibly the most widespread use of lead today in the US is in the form of the lead sulphate (PbSO4) electrodes that are a crucial component of wet-cell batteries, which thanks to this use, are known informally as "lead-acid batteries", of the type found in many cars. Lead acid batteries have many advantages, among them their dirt cheap base materials, but are increasingly replaced due to their downsides like high weight and low energy density. During the Great Depression, 59 poor African Americans were poisoned after burning the casing from lead-acid batteries to keep warm.[17]:30

It's also used for those little weights they add to your wheels whenever you get new tires, to balance them.

Because of its density (and cheapness), it's great for shielding against radiation. Lead aprons are frequently used for shielding against X-rays in medicine, but gold is typically used in household applications such as to shield the americium in smoke detectors due to its nontoxicity, even if it is several orders of magnitude more expensive.

Romans also used lead as an artificial sweetener. Really, it's a wonder they survived as long as they did.[42] Lead is also found in tobacco smoke, as if there weren't already enough reasons to avoid it.[43]

Lead oxide is sometimes added to glass to make it stronger. It was often used in china and glassware used for drinking, but these uses have largely been thrown into the dustbin of history due to lead's toxicity. Lead glass is still used today for stained glass windows, however, and it can also protect against radiation.

Uranium-lead dating is considered the most reliable form of radiometric dating, as lead is relatively stable in rocks, compared to things like strontium and rubidium which have a tendency to move to older rocks. The one problem is that uranium's long half-lives of 710 million years (for U-235) and 4.5 billion years (for U-238) make it only useful for dating old rocks, but it's still great evidence against a recent creation.[44]

At least 98% of lead in use today gets recycled, more than any other non-alloyed metal.[45] However, lead recycling is unregulated in many places, and recycling operations in developing countries are resulting in exposing workers and the environment to dangerous levels of lead.[46]

In pseudoscience[edit]

Anglesite, beautiful but deadly.

Lead and tin are used in molybdomancy, a type of divination involving pouring molten metal into water.

In traditional Chinese medicine, lead is supposed to be good for detoxing (you read that right), malaria, ringworm, skin rashes, rosacea, eczema, sores, ulcers, and killing intestinal parasites, among other things.[47] It's also used in unani and Ayurvedic medicine.[35] Lead was also used as medicine in ancient Rome.[15]

Lead is also used around the world as a folk remedy for things like upset stomach, constipation, diarrhea, vomiting, colic and teething.[48][49] Ironically, lead was known to cause colic since 1767.[16]

Lead sometimes appears in homeopathy medications, as “plumbum aceticum”.[50] There are claims from the early 20th century that it can treat things like excessive salivation and madness induced by syphilis, though the practitioners back then at least had the sense to acknowledge the existence of lead poisoning.[51]

Lead crystals are sometimes used in crystal healing. The most common one is galena, which is the most common lead ore.[52] Galena mostly is only dangerous if its dust is inhaled or ingested (as galena is pretty much insoluble), and it is sometimes used in student geology labs, but repeated exposure to it can be harmful.[53] Anglesite, on the other hand, is a lead sulfide crystal that is much more soluble and is also very sensitive to heat and pressure, making it considerably more dangerous,[54] but that doesn't stop some woo pushers from advocating its use in crystal healing.[55]

Although it's more of a protoscience, lead had many uses in alchemy. Lead had the symbol ♄ and was associated with the planet Saturn. It was considered the oldest of the seven alchemical metals, the others being gold, silver, mercury, copper, iron, and tin.[56] The most famous use of lead by alchemists is that they wanted to turn it into gold using a mythological "philosopher's stone". Today, this is actually possible through the use of particle accelerators, although any gold you get out of this process will be radioactive.[57]

Not sources of exposure[edit]

Graphite, used in pencils, contains no actual lead.

Despite its name, "pencil lead" has never been made of lead; it was at one point made from a form of graphite that was mistaken for the metal. They are instead graphite (a type of crystalline carbon, once called "Plumbago") bound together with a little bit of clay. So anyone who cautions you about contracting lead poisoning from pencils is someone you probably don't want to take advice from in other areas.

"Go over like a lead balloon" is an idiom that means disastrous results. The band Led ZeppelinWikipedia got its name when Keith Moon of The WhoWikipedia said the band would go over like a lead balloon. They decided to replace the balloon with the heavier-sounding German airship known as the Zeppelin, and spelt it as "Led" so no one would mispronounce their name.[58] Obviously, no actual Zeppelins were ever made of lead.[citation NOT needed]

See also[edit]

  • Clair Patterson — largely responsible for eliminating tetraethyl lead from gasoline
  • Coal is not kohl.

External links[edit]

Notes[edit]

  1. Although gold has the benefit of being able to be cut into really thin sheets, so in applications where only the surface needs to be coated (such as coating the americium-241 in smoke detectors), using gold won't jack up the price too much.
  2. Midgley is also credited with inventing the CFCs that would go on to damage the ozone layer. He had a truly terrible track record when it came to his inventions.

References[edit]

  1. LEAD, 444.pdf'
  2. The radioactive series of radium-226
  3. Radioactive Decay, United States Environmental Protection Agency
  4. Tungsten Price, Metalary
  5. Change in gold price from 1900 to 2020, Statista January 2021 ($1,268.49 per troy ounce, 33150.7 troy ounces in a metric ton, so a metric ton cost $40,782,841.44)
  6. Average prices for lead worldwide from 2014 to 2025, Aaron O'Neil, Statista 14 September 2021
  7. See: “America’s Real Criminal Element: Lead” Mother Jones. Summed up by The Straight Dope: "The gist is that violent crime in the U.S., which rose sharply after 1960 and plummeted after 1990, tracked closely with per capita use of lead in gasoline, offset by 23 years. In other words, kids whose heads were messed up by high exposure to lead in infancy went on to become violent criminals as adults."
  8. Lead Poisoning and Rome, University of Chicago
  9. Compliance FAQs: RoHS, NIST
  10. International Agency for Research on Cancer: Inorganic and Organic Lead Compounds
  11. Information for Workers: Health Problems Caused by Lead Centers for Disease Control and Prevention
  12. 12.0 12.1 Lead poisoning and health World Health Organizations
  13. Aggregate-level lead exposure, gun violence, homicide, and rape, Brian B. Boutwell et. al, NCBI 27 November 2017
  14. Lead Exposure In Childhood Linked To Lower IQ, Lower Status, Karl Leif Bates, Duke Today, 28 March 2017
  15. 15.0 15.1 Vitruvius, Lead Pipes and Lead Poisoning by A. Trevor Hodge (1981) American Journal of Archaeology 85(4):486-491.
  16. 16.0 16.1 16.2 16.3 Lead Poisoning: Historical Aspects of a Paradigmatic "Occupational and Environmental Disease" by Michele Augusto Riva et al. (2012) Saf. Health Work 3(1):11-16.
  17. 17.00 17.01 17.02 17.03 17.04 17.05 17.06 17.07 17.08 17.09 17.10 17.11 17.12 17.13 17.14 Lead Wars: Lead Wars: The Politics of Science and the Fate of America's Children by Gerald Markowitz & David Rosner (2014) University of California Press;. ISBN 0520283937.
  18. How We Ended Up With Lead Piping And Why Removing It Will Be Hard by Irina Zhorov (Feb 29, 2016) WESA (NPR).
  19. The accident that started it all, Mike McNessor, Hemmings 27 February 2012
  20. This is why you don’t remember engine knocking, Landon Hall, Fuel Freedom Foundation 28 July 2016
  21. Thomas Midgley Jr.: The Man Who Harmed the World the Most, Susan Fourtané, Interesting Engineering 6 August 2018
  22. EPA Takes Final Step in Phaseout of Leaded Gasoline (EPA press release - January 29, 1996) United States Environmental Protection Agency
  23. Leaded Gasoline Use in Vehicles Has Now Officially Ended Worldwide, Elizabeth Gamillo, Smithsonian Magazine 31 August 2021
  24. Aviation Gasoline, FAA
  25. Lead paint poisons thousands of Pa. children each year. Advocates say now is the time to act, Brett Sholtis, witf 2 July 2021
  26. Some Less Well-Known Lead Pigments, A.H. Sabin, The Scientific Monthly January 1932
  27. Buried lead, Lauren Rosenthal and Will Craft, APM reports 4 May 2020
  28. Is there still a problem with lead in drinking water in the European Union?, C.R. Hayes and N.D. Skubala, NIH December 2009
  29. Flint Water Crisis: Everything You Need to Know, Melissa Denchak, NRDC 8 November 2018
  30. Former Michigan Gov. Rick Snyder charged in Flint water crisis, Doha Madani and Erin Einhorn, NBC News 13 January 2021
  31. Zapping Lead Pipes with Electricity Could Make Them Safer for Drinking Water, Angus Chen, Scientific American 4 April 2019
  32. New Poll: Overwhelming Bipartisan Support for Funding Lead Pipe Replacement, EDF 11 March 2021
  33. Composition of eye cosmetics (kohls) used in Cairo by A. Hardy et al. (2004) Int. J. Environ. Health Res. 14(1):83–91.
  34. Composition of eye cosmetics (kohls) used in Oman by A. D. Hardy et al. (1998) J. Ethnopharmacol. 60(3):223–34.
  35. 35.0 35.1 Kohl (surma): Retrospect and prospect by Zafar Alam Mahmood et al. (2009) Pakistan Journal of Pharmaceutical Sciences 22(1):107-22.
  36. Lead in Cosmetics, FDA
  37. Wildlife, human and environmental costs of using lead ammunition: An economic review and analysis, Deborah J. Pain et al., Ambio 16 March 2019
  38. Lead Still Used in Ammunition, American Bird Conservatory
  39. Lead shot to be phased out, George Brown, GunsOnPegs 24 February 2020
  40. Health and Environmental Risks from Lead-based Ammunition: Science Versus Socio-Politics, John M. Armeno et al., NCBI 23 September 2016
  41. Trump Administration Revokes Lead Bullet Ban, But California's May Hold, Katrin Snow, KQED 2 March 2017
  42. Lead Poisoning and Rome Encyclopædia Romana by James Grout (1997-2017)
  43. Trends in Tobacco Smoke Exposure and Blood Lead Levels Among Youths and Adults in the United States: The National Health and Nutrition Examination Survey, 1999–2008, Patricia A. Richter et al., CDC 18 December 2013
  44. Principles of isotopic dating, Edwin A. Olson, Britannica
  45. Bergsöe completes the cycle, Richard Cutler, New Boliden
  46. Getting the Lead Out: Why Battery Recycling Is a Global Health Hazard, Fred Pearce, Yale Environment 2 November 2020
  47. Galena, Acupuncture Today.
  48. Folk Medicine Centers for Disease Control
  49. Managing Elevated Blood Lead Levels Among Young Children: Recommendations from the Advisory Committee on Childhood Lead Poisoning Prevention, edited by Birt Harvey (2002) Centers for Disease Control and Prevention, pages 120-122.
  50. U.S. Food and Drug Administration. (June 11, 2020). Warning Letter - Hevert Pharmaceuticals LLC USA - 594842. Center for Food Safety And Applied Nutrition.
  51. Clarke, John Henry (1905). Materia Medica. 
  52. Galena, Sage Crystals
  53. 9 Deadliest Rocks And Minerals On Earth, Trevor Nace, Forbes 14 February 2016
  54. Anglesite, Gemstone Dictionary
  55. Anglesite, Healing Crystals
  56. Lead, Royal Society of Chemistry
  57. Can We Transform Lead Into Gold?, Salama Yusuf, Science ABC 6 August 2021
  58. How Did Led Zeppelin Choose Their Name, Rock Music Revival