You know what I’m talking about. We’ve all been there: it starts with an ominous rumbling sound, often more felt than heard. Somewhat like a gastrointestinal earthquake of low magnitude. Stomach ache, nausea and an emergency high-speed waddle to the loo follow in rapid succession. Dehli Belly, Montezuma’s Revenge – whatever euphemism you employ, only one cogent thought is running through your head, over and over again:

"What did I eat? Oh dear god, what did I eat?"

Inspiration strikes – not too hard in this case, seeing as you skipped breakfast to get to the lab early, and the only thing you’ve eaten all day is…that damned pizza! It had to have been the slice of sausage pizza at the department social before the seminar. Most of us have been through this situation at some point, and more often than not it’s just put down to a "bug". Just bad luck: food bugs do get around.

But if you work in a lab it can be a bit more unnerving. Especially when as you start to feel rough, you glance around the seminar room and see that everyone else who ate the pizza seems to be in no discomfort whatsoever – obvious from their nodding heads and trail of drool as they doze though another dull talk conducted by some poor sap at the podium desperately trying to make his research sound interesting to a bunch of people who would rather be doing something else – anything else – than sitting through it.

One runs mentally through the entire day up to that point, trying to figure out what could be causing this "discomfort" – an understatement given the potentially explosive nature and socially crippling timing of the problem. The list is usually alarmingly long; in fact, the whole exercise does nothing to assuage fear, but only makes it worse. Was it the sodium fluoride in that solution I made up? That’d be bad. Or maybe it was ethidium bromide: did I handle that agarose gel without gloves? Maybe there was a spillage of okadeic acid on the outside of that tube I grabbed. The list is long, frightening, and often potentially lethal.

I used to work in a lab in Washington DC studying a protein with the catchy name of TRPV1. It’s also known as the capsaicin receptor. Basically TRPV1 is the sensor that detects the ‘heat’ in chilli peppers, which is caused by a chemical known as capsaicin. On the Scoville Heat Scale of chilli products, a Habenero pepper comes in at around 250,000 units. Traditional grade pepper spray rates at a whopping 2,000,000 units, police-grade pepper spray is 5,300,000, and neat capsaicin comes in at a bastard 16,000,000. That’s pretty freaking hot by anyone’s standards.

Now, when not availing myself of free pizza at department socials, I make do, like many busy young scientists, with quick snacks from the vending machine and, of course, fingernails. Yes, I’m a fingernail biter (my own, more often than not). Despite my precautions while messing around with experiments (I’m very anal about wearing gloves in lab, and wash my hands frequently), there were nevertheless many times during my short and painful tenure in this lab when I would be at my computer analyzing some data and suddenly, my mouth would fill with the most intense burning sensation. I must have chewed a fingernail. Or worse, I would go blind in one eye, an icy-cold, yet burning-hot sensation spreading outwards from my tear duct. You guessed it: I probably rubbed an itch. It took ages for this burning to go away. However, I can now safely eat hot-wings with no real discomfort. Even with my eyes.

But capsaicin was the least of my worries. I work, as many of us do, with much nastier chemicals than hot sauce. Most of the solutions I use on a daily basis would make you very sick indeed, if not kill you. Painfully. But despite all precautions, we get all kinds of substances on our hands, and thence elsewhere.

All labs, at least in the developed world, are under the fairly close scrutiny of the Environmental Health and Safety Office (EHS) or equivalent. Each university or company will have an EHS whose job seems to be to interrupt your day and ruin your carefully timed experimens by making you change out of sandals in the middle of summer, or move boxes from high shelves (so they don’t block sprinkler systems), or get you in trouble when they find your lunch in the fridge with the cold chemicals. Or, as in one lab I worked in, they find a six-pack of beers chilling in a minus 20 degrees freezer stuffed full of dead mice. Yummy! Pass me a cold one!

Anyway. One thing they all make you have is an MSDS book. That’s a big folder containing all the Material Safety Data Sheets for every chemical in the lab. My lab has two, and each is three inches thick. That’s a lot of chemicals. I had to reorganize our lab’s MSDS books just the other week. They make fascinating reading, especially the bits about how insanely dangerous some of the stuff is that you work with on a daily basis. There’s often a really morbid section about the "LD50s" of the chemical. That’s the dose it would take to kill 50% of any population (usually rodents). For all you voyeurs, there is sometimes even human data, documenting the time some poor sod unwittingly condemned him or herself to an early grave and a place in scientific posterity by ODing or ingesting, inhaling, absorbing or injecting something best left well outside the body.

Given the silly hours we often work, most scientists (and "normal" people too) are well aware that tiredness leads to accidents and mistakes. It’s a really horrible feeling to think you may be about to become one of those scary statistics in an MSDS report if you make a little mistake whilst going about your everyday lab business, like munching on a free slice of pizza before a seminar.

But there’s no time too worry, I’m too busy. Back to my experiments – but first, where did I leave that chocolate?