Perhaps the biggest difference between life now and life a generation ago is that we are all constantly connected to each other and to the internet.

The devices many of us use more than any other – both to talk on the phone and connect to the internet – are cell phones.

So it may seem scary that the California Department of Public Health has issued guidelines to help people "decrease their exposure to the radio frequency energy emitted from cell phones."

The department said the information was intended to help people who are concerned about health risks including brain tumours, lowered sperm counts, and effects on learning, memory, and sleep.

But California's new guidelines – and some of the news coverage they have inspired – can make it seem like using a cell phone carries far more risk than scientific evidence suggests.

Although some researchers are worried about the long-term effects of cell-phone use, so far there's not actually any evidence that the radiation emitted by smartphones causes harm.

The CDC's position is that there are no scientific findings that provide a definitive answer to the question of whether cell phone radiation causes cancer.

Most large studies documenting cancer rates haven't found significant evidence that cell phone use raises cancer rates or causes other negative health effects.

There are some good reasons to limit cell phone use, however.

What science says about cell phone radiation and health

California's department of public health suggested that people who want to reduce their risk of radiation exposure could take the following steps:

  • Keep the phone away from the body
  • Reduce cell phone use when the signal is weak (since searching for a signal could use more energy)
  • Reduce the use of cell phones to stream audio or video, or to download or upload large files
  • Keep the phone away from the bed at night
  • Remove headsets when not on a call
  • Avoiding products that claim to block radio frequency energy, since such items may actually increase your exposure

The main concern people have about cell phones is that they emit radio-frequency (RF) energy, a type of radiation.

Researchers have long wondered whether that could pose a threat to human health. But RF energy doesn't cause the DNA damage that radiation from the sun or from X-rays does, according to the National Cancer Institute. (DNA damage is the thing that leads to cancer.)

The International Agency for Research on Cancer (IARC) classifies RF energy as "possibly carcinogenic," but almost everything is "possibly carcinogenic," including coffee and pickled vegetables.

It's hard to definitively say that any substance doesn't cause cancer, even when we have evidence that substances like coffee are linked with lower cancer rates.

(Out of 968 substances IARC has evaluated, the only one they have concluded is "probably not carcinogenic" is a chemical used in yoga pants and toothbrush bristles.)

Given the widespread adoption of cell phone use, scientists would expect cancer rates to have spiked if usage was really risky. But that hasn't happened.

Most large scale studies looking at cancer rates don't show changes related to cell phone use.

One study that looked at more than 5,000 brain cancer cases in 13 countries found no increase in risk related to phone use, though it called for more research on the topic.

Two other studies looked at close to 800,000 women and more than 350,000 people in Denmark, and found no significant increase in cancer risk associated with cell phone use in either population.

The most recent scare on the topic came from an unreleased study being conducted by the US National Toxicology Program.

Researchers blasted rats with full-body doses of RF radiation (mostly at higher levels than those associated with cell phones) from the time they were born until they were two years old for nine hours a day.

They found that some male rats had higher tumour rates. But none of the control rats developed brain tumours as would have been expected, and the male rats exposed to radiation actually outlived their non-exposed counterparts.

"I'm not going to stop using my mobile phone in the light of this," Kevin McConway, emeritus professor of applied statistics at The Open University, said in a statement about that study.

However, heavy phone users who want to reduce their exposure to RF radiation in case future research reveals new risks can consider using a headset.

No reason to panic

The California guidelines describe the science as "evolving," which is accurate. It's always possible that there's some small increased risk scientists haven't identified yet.

Plus, some of the recommendations could be good ideas no matter what.

Research shows that people (especially children) don't sleep as well when they have immediate access to their phones, even if they don't use them. So keeping your phone away from the bed could help you sleep better.

Other research has shown that interruptions from phone notifications impair productivity and make people more prone to making mistakes. That means there could be other benefits to storing your cell phone in a backpack or desk instead of keeping it next to your body.

Furthermore, psychologists like Sherry Turkle argue that our obsession with our phones – or the apps on them – comes at the expense of human relationships.

That's not a radiation issue, but it may be a good reason to consider keeping your mobile device at arm's length.

Beyond the threat of radiation, there are many good reasons to continue studying how cell phones affect our lives. But California's new guidelines are just suggestions.

And while there may be benefits to reducing your cell phone use, there's no reason to panic about cancer.

This article was originally published by Business Insider.