Sick children rest at Patna hospital after consuming tainted school lunches. (STRDEL/AFP/Getty Images)

The tainted school lunches that killed 23 children and sickened many more in India this week are thought to have been contaminated with an insecticide called Organophosphorous. It's a nasty substance, so hazardous that its use in the United States declined by 55 percent between 1997 and 2007 but so common that, in 2001, Americans used 73 million pounds just that year. And it's especially common in India.

Bloomberg's Jason Gale and Ketaki Gokhale looked into the medical research around Organophosphorous, which turns out to have a record of killing more than just insects. Here are a few facts about the substance:

• It kills 200,000 people around the world every year

• It's closely related to sarin, a chemical weapon made famous by Saddam Hussein.

• More than 15 percent of cases of ingestion lead to death

• People who survive ingestion will sometimes develop paralysis later or neuropsychological problems, as the chemical is absorbed into the body's fat.

• Organophosphorous poisoning can be treated with atropine or other medicines, but only if it's administered at the exact right moment. Otherwise, it can worsen the effects. No one can agree when the right moment is.

• This is really tragic: Organophosphorous can produce a "peripheral respiratory failure." This means that, even after a patient has been treated and appears to be improving, a second round of respiratory symptoms will suddenly set in, sometimes fatally.