BehindTheMedspeak: Is it safe to eat moldy food if you cut off the moldy part?

Short answer shorter: No.

C. Claiborne Ray's July 22, 2008 New York Times Science section "Q.&A." has the longer version, and follows.

Mystery Molds

Q. I’ve been told not to eat food that has a little mold on it because the mold has permeated throughout. Is this true?

A. Yes, mold that is visible on the surface of food is only the tip of the iceberg, according to the United States Department of Agriculture.

Molds are fungi that have three parts: the root threads, which invade deeply into the food; a stalk, which rises above the food; and spores that form at the end of the stalk.

By the time the stalks are visible, the root threads, called hyphae, are embedded, so it is best to avoid food with any sign of mold.

Some molds can cause strong allergic reactions, including respiratory problems, in susceptible people. And in some varieties, the threads produce toxic substances called mycotoxins, which can make people very sick.

Molds may appear as “gray fur on forgotten bologna, fuzzy green dots on bread, white dust on Cheddar, coin-size velvety circles on fruits and furry growth on the surface of jellies,” as a fact sheet from the U.S.D.A. says. But molds have their good side; beneficial molds make blue cheese blue, and a common bread mold famously gave rise to the lifesaving drug penicillin. Also, molds play a big role in the decomposition of organic waste.