Our cellphones and laptops go everywhere with us — on the subway, to the grocery store, to work, even to the bathroom. How worried should you be about getting sick from your phone or laptop?

No more worried than you would be about getting sick from touching your other personal objects, said Jonathan Eisen, a microbiologist. An object such as a subway handrail or keyboard can harbor microbes including pathogens but those can make you sick only in the right environment and transmission method.

If you’re the only person using your laptop and phone in a normal, everyday environment, you’re basically sharing microbes with yourself.

The risk increases when you’re transferring microbes or coming into contact with other people. For example, if you’re using a recipe on your computer and handling raw meat. In this case, you could be transferring a harmful microbe, such as E. coli or salmonella, onto the keyboard.

If someone sneezes on your phone and you touch it and then your mouth, you could get sick, but only because you touched your mouth. Using a keyboard in a library or your phone on the subway with the same hand you used to touch the railing would be riskier, because you’re exposing yourself to other peoples’ microbes, Eisen said.

But haven’t we been told that our phones are dirtier than a toilet seat? Eisen said many studies fail to provide context. “Maybe it tells you something about how recently something was cleaned … but it doesn’t tell you anything about the health risk.”

Both helpful and harmful microbes exist everywhere. “This is not about eliminating risk, it’s about reducing risk,” Eisen said.