The urge to eat crayons

John, from Washington State, sends this item from The Korea Herald:

"Dear Annie: I am a 35-year-old woman with four children, an advanced degree and no serious health problems, but I have compulsively and secretly been eating crayons for months. I don't mean chewing on a crayon here and there. I mean eating an entire 64-count box, and doing it several times a week. I can't stop, and I don't know why I'm doing this. I am too embarrassed to tell my doctor, because I know he'll think I am crazy. The box says the crayons are non-toxic, but I'm really eating a lot of them. And this is a really dumb question, but are they fattening? Why am I doing this? Am I crazy? Please help. -- Crayon Freak"

This comes via Dave Barry's Blog. There's a spirited discussion in the comment thread, including some dining tips ("The Red-Violet is excellent with herb butter and paprika").

The question, "Are they fattening?", suggests further issues to explore, but the advice columnist ventures a diagnosis of pica. Patients with pica eat "non-food substances." Here are DSM-4 criteria, and here's an article from eMedicine:

Pica is an eating disorder typically defined as the persistent eating of nonnutritive substances for a period of at least 1 month at an age in which this behavior is developmentally inappropriate (eg, >18-24 mo). The definition occasionally is broadened to include the mouthing of nonnutritive substances. Individuals presenting with pica have been reported to mouth and/or ingest a wide variety of nonfood substances, including, but not limited to, clay, dirt, sand, stones, pebbles, hair, feces, lead, laundry starch, vinyl gloves, plastic, pencil erasers, ice, fingernails, paper, paint chips, coal, chalk, wood, plaster, light bulbs, needles, string, and burnt matches.

Although pica is observed most frequently in children, it is the most common eating disorder seen in individuals with developmental disabilities. In some societies, pica is a culturally sanctioned practice and is not considered to be pathologic. Pica may be benign, or it may have life-threatening consequences.

I'm doubtful that the crayons will do much harm, but I would be asking a lot more questions, and not just about eating habits.

I'm more worried about this performance artist, who goes beyond the compulsive ingestion of crayons. She's eating a wall of an art gallery:

Five days a week, Ms. Katrencik consumes a section of wall 1.956 inches square and three sheets of drywall thick, for a total of about 8.5 cubic inches of drywall; she rests on Sundays and Mondays. Each meal takes about half an hour. She began on Jan. 1, to ensure that there would be a sizable hole before the (exhibit) opening on Jan. 28, and will keep it up until the exhibition closes on Feb. 27, at which time she calculates the hole will be large enough to stick your head through. She usually gnaws directly on the wall, working away at a sizable, eye-level hole, and avoids eating when the public is present. Video of her ingestion is included in the exhibition; she also removes some of the plaster and bakes it into loaves of bread, which are available for gallery visitors to sample. "Part of it is that I'm really broke," she said, "so this is a way to get the gallery to cover my food costs."

...So how is this diet affecting her health? "I try not to think about it," she said. "Instead, I look at the things in the wall that are good for me, like calcium and iron." One of the main components of drywall is calcium sulfite, she noted, a mineral that can be found in tofu, canned potatoes and some baked goods. She said that she had not had any digestive problems, but was careful to eat a lot of vegetables to balance the binding effect of the plaster. And the taste? "This drywall tastes pretty chalky," she said. "I prefer cast concrete because it has a more metallic flavor. You can taste the iron."

I'm wondering why the gallery is allowing this to occur...