A study is research with scientific experiment and documentation to evaluate a set of cause and effect phenomena.
A review is an evaluation of existing data wherein new evidence from years after the data was published would not be included in the body of information.
Because the scientific knowledge around the technology of high volume hydraulic fracturing has grown exponentially over the past 4-5 years, any review of data that does not include current knowledge would not be a valid report regarding the health impact of HVHF / fracking.
Please read the letter to Gov Cuomo signed by many health professionals and organizations calling for a health impact study with specific regards to radium and radon:
...to conduct studies and a human health risk assessment of the occurrence of radon and radium during drilling for natural gas before deciding whether to allow drilling in New York’s portion of the Marcellus shale or the distribution to New Yorkers of Marcellus shale gas containing unhealthy levels of radon ...