[Gyvfdc]

Hi
Yesterday me and my friends were having a bit of fun in the chemistry classroom and one of my friends' shoe ended up in my bag. I did not think anything of it at the time, however later at lunch I noticed, that it had come in contact with my lunchbox. However I just brushed it off and ate my lunch. The problem is that afterwards I got really afraid that the shoe might have picked up some contaminants since we were in the chemistry classroom. I don't know whether i'm just overthinking it, but I would really like a second opinion.
Thanks in advance

[P]

If you still haven't died in 3 days time then I think you will be OK.   

[Borek]

Sadly, people are so scared of chemistry they almost think it is enough to look at chemicals to get poisoned. It is not, in case you wonder

Yes, chemicals can be dangerous. Sharps knives, scissors, hammers, cars, stones and sticks can be dangerous too, I hope you are not afraid of using them.

Reagents used at schools are already selected for their safety, you would have to eat them in large amounts to get sick. Standard precautions are perfectly enough.

Don't let chemophobia ruin your attitude to chemistry and sciences in general.

[Corribus]

It's fundamentally a problem of risk perception and the fact that experts perceive risks different than laymen:

No one seems to deny that experts rationalize hazards against dosage and exposure. The public does not. For example, "the public would have more of an all or none view of toxicity....[T]hey appear to equate even small exposures to toxic or carcinogenic chemical with almost certain harm". As well put elsewhere, when a young child drops a lollipop on the floor, the brief contact with dirt causes the parent to throw it away rather than washing it off and returning it to the child.

(From: Berube, D. M. in Nanotechnology and Society: Current and Emerging Ethical Issues (eds Allhoff, F. & Lin, P.) 91–107 (Springer, 2009).)

The media doesn't help to dispel the notion that dosage in unimportant, and nor does it help to dispel the common perception that chemicals are just plain dangerous. In fact, people don't even seem to understand what a chemical is. When I see a consumer product like a lotion or shampoo being advertised as "chemical free", I just groan with annoyance.

[Enthalpy]

In some occasions, the public is more confident than the experts. Think of sodium hydroxide to destroy organics in the sinkhole: chemists may well wear goggles for that. Nor would chemists pee on hypochlorite, would you?

Explosives are an extreme case. On new year's eve, the public ignites rockets with explosive heads from 0.5m distance. I know a few pyrotechnists, all told me "Never will I" and "Accidents are no wonder then".

Not to mention software...