Lead and pica
As Jamie Lincoln Kitman explains at great length in this Nation story from March 2000 (which Brad Plumer thoughtfully linked to recently) "unleaded gasoline" is a phrase that serves as a semantic relic of a fairly despicable chapter in American industrial history -- the deliberate use of lead in gasoline despite the knowledge that it was extremely poisonous and that there were viable alternatives to use as anti-knock additives. Though written with more evident outrage than I would prefer (I like it when writers trust me to become sufficiently outraged on my own), Kitman's story unfolds the details of how gasoline ever got leaded in the first place. The upshot is that GM and DuPont conspired to control the research into lead's dangers to protect the monopoly they had on gasoline additives (TEL, tetraethyl lead), which gave them what amounted to a royalty on every gallon of gas sold in most countries around the world. Company shills put out memorable press releases like this:
[TEL's] recently discovered use for greatly promoting the efficiency of gasoline engines has led to its manufacture on a commercial scale through processes still more or less in a stage of development. This has occasioned unforeseen accidents.... One of these has been the sudden escape of fumes from large retorts, and the inhalation of such fumes gives rise to acute symptoms, particularly congestion of the brain, producing a condition not unlike delirium tremens. Although there is lead in the compound, these acute symptoms are wholly unlike those of chronic lead poisoning such as painters often have. There is no obscurity whatever about the effects of the poison and characterizing the substance as 'mystery gas' or 'insanity gas' is grossly misleading.
This is a pretty compelling in a Don Delillo White Noise sort of way, but what I found especially surprising in the article was this:
Working alongside Kehoe at first was the Lead Industries Association. Formed primarily to fight restrictions on the use of lead paint, the LIA was also ready to serve as a sort of all-purpose lead-issue obfuscator. Though it wouldn't fund much actual research, the LIA would underwrite the original studies at Harvard in the twenties that isolated a new pseudo-psychological malady named "pica," the so-called unnatural impulse of some small children, mostly nonwhite, to stick lead paint chips in their mouths.
Pica, a pseudo-disease? I've long been fascinated by pica phenomenon, primarily because it is such a strange eating disorder. Here's a rather bizarre account of pica from this children's health website
Theories about what causes pica abound. The nutritional theory suggests that nutritional deficiency, such as iron deficiency, trigger specific cravings. Some evidence supports the hypothesis that at least some pica is a response to dietary deficiency - nutritional deficiencies are often associated with pica and correction of that deficiency has improved symptoms. Some pregnant women, for example, have stopped eating nonfood items after they were treated for iron deficiency anemia, a common condition among pregnant women with pica. However, not everyone responds when a nutritional deficiency is corrected, which may be a consequence of the behavior (rather than the cause). But there are also people with pica who don't have a documented nutritional deficiency.Reading this sort of thing has fueled my fascination: The idea that people are out there eating dirt out of "daily habit" makes me want to write a short story. Since I've heard of it, I've always thought that pica is a perfect metaphor for something about our culture -- something about being compelled to eat something that's not actually food, that has no actual nutritional benefit, seems redolent of consumerism as a whole.
Known as geophagia, eating earth substances such as clay or dirt is a form of pica that can cause iron deficiency. One theory to explain pica is that in some cultures, eating clay or dirt may help relieve nausea (and therefore, morning sickness), control diarrhea, increase salivation, remove toxins, and alter odor or taste perception; some people actually claim to enjoy the taste and texture of dirt or clay. Some people eat clay or dirt as part of a daily habit (just like smoking is a daily routine for others). And some psychological theories explain pica as a behavioral response to stress or an indication that the individual has an oral fixation (is comforted by having things in his or her mouth).
Another explanation is that pica is a cultural feature of certain religious rituals, folk medicine, and magical beliefs. For example, some people in various cultures believe that eating dirt will help them incorporate magical spirits into their bodies.
Despite the wide variety of theories, not one of them explains all forms of pica. A doctor must treat every case individually to try to understand what may be causing the condition.