Risk to human health from nuclear fuel particles found on Sandside Bay near the Dounreay is 'low', according to environment agency Sepa.
Research has been carried out on Sandside Bay near Dounreay
The study said the chances of the public being exposed to a particle was 'one in a million per year'.
The Health Protection Agency, who Sepa commissioned to do the research, said particles found so far on the Caithness beach were relatively low in activity.
But Sepa warned fragments of greater activity had been found offshore.
About 50 particles have been found on Sandside since 1984.
Sepa commissioned the Health Protection Agency (HPA) to study the risks of being exposed to a particle and the chances of coming into contact with one.
Research considered the most likely groups to encounter the tiny fragments - including people digging for bait, dog walkers and children playing on Sandside beach.
The report said: "The results indicate that the probability of encountering a fuel fragment on Sandside beach is less than one in a million per year."
The odds of encountering one of the larger particles rose to less than one in 80 million.
Dr Paul Dale, of Sepa, said a person would need to have one of the particles found so far on the beach on their skin for seven hours for it to cause a burn.
The wound would be expected to heal within one to two weeks.
Dr Dale said: "The particle would have to remain on the same area of skin and not move at all or be washed off for skin burn to happen."
He said larger particles than those discovered on the beach lie on the seabed offshore, but there was no evidence of them washing onshore.
Dr Dale said Sepa would continue to monitor the situation.
In a statement marking the publication of the research on Tuesday, Sepa said: "Particles found on Sandside Beach to date are relatively low in activity and any affect on human health is likely to be short term.
"Should a particle be detected on the beach with higher activity than those discovered there is the potential for short-term visible effects to occur through skin contact."
Dounreay site operators, the United Kingdom Atomic Energy Authority, said: "We welcome the report.
"It is obviously an important piece of work and another piece of the jigsaw for our consultation on the long term management of particles in the environment."
The options to deal with particles range from doing nothing to dredging the seabed.