# DDT Causes Egg Shell Thinning? **URL:** \ **Category:** Factual Questions\ **Created:** [October 11, 2016, 7:15pm UTC](https://boards.straightdope.com/t/ddt-causes-egg-shell-thinning/768271 "2016-10-11T19:15:23Z")\ **Posts on this page:** 10\ **Page:** 1
**Author:** ![barbitu8](https://avatars.discourse-cdn.com/v4/letter/b/839c29/32.png) [@barbitu8](https://boards.straightdope.com/u/barbitu8)\ **Post date:** [October 11, 2016, 7:15pm UTC](https://boards.straightdope.com/t/ddt-causes-egg-shell-thinning/768271/1 "2016-10-11T19:15:23Z")
Rachel Carson’s book, “Silent Spring” was the impetus in banning DDT. She claimed, among other allegations, that it caused the thinning of the egg shells of Eagles. Since it was banned, the bald eagle has been removed from the endangered list, so it is obvious that the eagle population has increased. However, it is also claimed that the ban has caused millions of deaths as it was an effective cure for malaria, and that the rise in the eagle population was caused, not by the DDT ban, but by laws prohibiting their shooting. [http://www.foxnews.com/story/2006/07/06/bald-eagle-ddt-myth-still-flying-high.html](http://www.foxnews.com/story/2006/07/06/bald-eagle-ddt-myth-still-flying-high.html) [http://www.wsj.com/articles/SB116727843118861313](http://www.wsj.com/articles/SB116727843118861313) But contra: [https://www.fws.gov/midwest/eagle/recovery/biologue.html](https://www.fws.gov/midwest/eagle/recovery/biologue.html) See also [DDT, Eggshells, and Me](http://reason.com/archives/2004/01/07/ddt-eggshells-and-me/) So, what is the straight dope? ---
**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:** [October 11, 2016, 7:34pm UTC](https://boards.straightdope.com/t/ddt-causes-egg-shell-thinning/768271/2 "2016-10-11T19:34:29Z")
How many people were shooting bald eagles? ---
**Author:** ![Amateur\_Barbarian](https://avatars.discourse-cdn.com/v4/letter/a/59ef9b/32.png) [@Amateur\_Barbarian](https://boards.straightdope.com/u/Amateur_Barbarian)\ **Post date:** [October 11, 2016, 7:42pm UTC](https://boards.straightdope.com/t/ddt-causes-egg-shell-thinning/768271/3 "2016-10-11T19:42:53Z")
There has been talk of returning DDT to the arsenal, but under very stringent usage conditions. It’s highly effective against bedbugs, for example, when very little else is. The problem was that DDT was safe for humans, and thus thought to be safe all around except for bugs, and thus dumped in megatonne quantities rather than being used with any selectivity. Very few ag chemicals are allowed to be used that way now; adding DDT to the list under good controls would not have the effect it had in the 1950s/60s. Or need not. ---
**Author:** ![watchwolf49](https://avatars.discourse-cdn.com/v4/letter/w/e9c0ed/32.png) [@watchwolf49](https://boards.straightdope.com/u/watchwolf49)\ **Post date:** [October 11, 2016, 8:08pm UTC](https://boards.straightdope.com/t/ddt-causes-egg-shell-thinning/768271/4 "2016-10-11T20:08:12Z")
**The Master’s** article about this: [“Was Rachel Carson a fraud and is DDT actually safe for humans?”](http://www.straightdope.com/columns/read/2428/was-rachel-carson-a-fraud-and-is-ddt-actually-safe-for-humans) … Basically what **Amateur Barbarian** said above … The Willamette Valley here in Oregon is thick with these Bald Eagles in winter. They’re the primary scavenger once the Turkey Vultures migrate south for the winter. However, as I understand the matter, the Columbia River Valley is all but devoid of Bald Eagles, whatever is reducing their populations is still leaching out into the water. I have no idea if it’s DDT or not. ---
**Author:** ![lucid-nonsense](https://avatars.discourse-cdn.com/v4/letter/l/2acd7d/32.png) [@lucid-nonsense](https://boards.straightdope.com/u/lucid-nonsense)\ **Post date:** [October 11, 2016, 8:33pm UTC](https://boards.straightdope.com/t/ddt-causes-egg-shell-thinning/768271/5 "2016-10-11T20:33:21Z")
DDT was never banned for pest control, only agriculture. If anything, not using DDT for agriculture slowed down the development of mosquitoes’ resistance and saved lives. The notion that environmentalists (or even Rachel Carson personally – she never argued that DDT should be banned) are responsible for millions of malaria death is nothing but base slander. ---
**Author:** ![Sailboat](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/sailboat/32/461_2.png) [@Sailboat](https://boards.straightdope.com/u/Sailboat)\ **Post date:** [October 11, 2016, 9:10pm UTC](https://boards.straightdope.com/t/ddt-causes-egg-shell-thinning/768271/6 "2016-10-11T21:10:21Z")
It’s also been thoroughly debunked, here and elsewhere. DDT was never banned in Africa, where people die from malaria…nor would US law have significant effect there. Mosquito-control authorities generally reserve DDT for emergencies; otherwise malarial mosquitoes would quickly evolve resistance and make it useless anyway. ---
**Author:** ![even\_sven](https://avatars.discourse-cdn.com/v4/letter/e/dfb087/32.png) [@even\_sven](https://boards.straightdope.com/u/even_sven)\ **Post date:** [October 11, 2016, 9:49pm UTC](https://boards.straightdope.com/t/ddt-causes-egg-shell-thinning/768271/7 "2016-10-11T21:49:11Z")
It’s already been said, but DDT can be and is used for mosquito control. The idea that it isn’t is a myth perpetuated by people with an agenda. ---
**Author:** ![CalMeacham](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/calmeacham/32/35_2.png) [@CalMeacham](https://boards.straightdope.com/u/CalMeacham)\ **Post date:** [October 11, 2016, 11:28pm UTC](https://boards.straightdope.com/t/ddt-causes-egg-shell-thinning/768271/8 "2016-10-11T23:28:20Z")
I never heard that it was Bald Eagle egg-shell thinning, but egg shell thinning in general. Two minutes of internet searching turns up this: > [@](#): > > J Toxicol Environ Health. 1977 Nov;3(4):699-704. > > Effects of DDT on eggshell quality and calcium adenosine triphosphatase. > > Kolaja GJ, Hinton DE. > > Abstract > > Adult mallard ducks were fed a diet containing 50 ppm DDT for 6 months. Eggs laid during this period were collected and eggshell weight, thickness, and calcium were determined. Chronic ingestion of DDT resulted in production of eggshells that were significantly thinner and lighter than those of controls. Total calcium of thinned eggshells was also reduced; however, calcium per gram of eggshell was not altered, indicating that other eggshell constituents were not incorporated as well. > **[Effects of DDT on eggshell quality and calcium adenosine triphosphatase - PubMed](https://pubmed.ncbi.nlm.nih.gov/145496/)** > > Adult mallard ducks were fed a diet containing 50 ppm DDT for 6 months. Eggs laid during this period were collected and eggshell weight, thickness, and calcium were determined. Chronic ingestion of DDT resulted in production of eggshells that were... The paper’s been cited 17 times according to Google Scholar, and a quick view of them doesn’t seem to turn up anyone arguing with it. ---
**Author:** ![RenaissanceMan203](https://avatars.discourse-cdn.com/v4/letter/r/94ad74/32.png) [@RenaissanceMan203](https://boards.straightdope.com/u/RenaissanceMan203)\ **Post date:** [October 12, 2016, 7:53am UTC](https://boards.straightdope.com/t/ddt-causes-egg-shell-thinning/768271/9 "2016-10-12T07:53:40Z")
> [@CalMeacham](#): > > I never heard that it was Bald Eagle egg-shell thinning, but egg shell thinning in general. > > Two minutes of internet searching turns up this: > > [Effects of DDT on eggshell quality and calcium adenosine triphosphatase - PubMed](https://www.ncbi.nlm.nih.gov/pubmed/145496) > > The paper’s been cited 17 times according to Google Scholar, and a quick view of them doesn’t seem to turn up anyone arguing with it. I guess the question would be is ingestion of 50 ppm of DDT for 6 months a realistic scenario on which to have relevant data? What is considered to be significantly thinner? I have had duck eggs before, and the shells are definitely thicker than a chicken egg. Or is this another case of skewing data to fit an agenda in the vein of feeding lab rats 5 million times the normal exposure of a random chemical in order to claim it as a carcinogen? My two minutes of the Google came up with this: > [@](#): > > Consider, for example, this passage from Edwards’ article: “This implication that DDT is horribly deadly is completely false. Human volunteers have ingested as much as 35 milligrams of it a day for nearly two years and suffered no adverse effects. Millions of people have lived with DDT intimately during the mosquito spray programs and nobody even got sick as a result. The National Academy of Sciences concluded in 1965 that ‘in a little more than two decades, DDT has prevented 500 million [human] deaths that would otherwise have been inevitable.’ The World Health Organization stated that DDT had ‘killed more insects and saved more people than any other substance.’” Article to be found here: [http://www.forbes.com/sites/henrymiller/2012/09/05/rachel-carsons-deadly-fantasies/#7f0e8b2115d1](http://www.forbes.com/sites/henrymiller/2012/09/05/rachel-carsons-deadly-fantasies/#7f0e8b2115d1) ---
**Author:** ![Atamasama](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/atamasama/32/12961_2.png) [@Atamasama](https://boards.straightdope.com/u/Atamasama)\ **Post date:** [October 12, 2016, 1:31pm UTC](https://boards.straightdope.com/t/ddt-causes-egg-shell-thinning/768271/10 "2016-10-12T13:31:19Z")
> [@lucid-nonsense](#): > > DDT was never banned for pest control, only agriculture. If anything, not using DDT for agriculture slowed down the development of mosquitoes’ resistance and saved lives. The notion that environmentalists (or even Rachel Carson personally – she never argued that DDT should be banned) are responsible for millions of malaria death is nothing but base slander. DDT stopped being used to kill mosquitoes because over time (only 7-10 years due to insects’ short breeding cycle and tendency to produce many offspring) the DDT-resistant mosquitoes were the only ones left in those areas. It was basically natural selection. Once DDT stopped killing mosquitoes it was abandoned.