It has been more than four years since the catastrophic meltdown of a nuclear reactor at the Fukushima Daiichi nuclear plant in Japan, but researchers are finally finishing their first round of studies on the health effects of exposure to nuclear radiation, and the prognosis does not look good.

According to a report from Philly.com, a recent study suggests that long-term exposure to low levels of radiation can significantly increase a worker’s chances of developing cancer. Researchers hope that the new study will help governments begin the process of adopting more stringent nuclear regulations in an effort to prevent a catastrophic meltdown like Fukushima from happening again.

According to the researchers behind the study, “This study provides evidence of a linear increase in the excess relative rate of cancer mortality with increasing exposure to ionizing radiation at the low dose rates typically encountered in the nuclear industries in France, the U.K., and the U.S.A.”

The research was published in the journal BMJ on October 20 and examined data from over 308,000 workers in nuclear power plants in the United States, the United Kingdom, and France. The study followed these plant workers for an average time period of 27 years.

Aside from leukemia, the estimated death rate from all other types of cancers rose by 48 percent per gray in people who spent years working at a nuclear power plant. Roughly 209 of the 19,064 cancer deaths among nuclear workers was linked to exposure to low levels of radiation.

The study found that the risk per unit dose of radiation was a similar measure to that observed in survivors of the atomic bomb attacks in Japan in 1945. The study argues that prolonged exposure to low levels of radiation is just as dangerous as brief periods of intense exposure.

The study still fails to prove a causal link between the cancer deaths and the workers’ radiation exposure. Factors like smoking, asbestos in the workplace, and poor diets can all contribute to cancer outcomes.