"be of significant concern" is correct and usable in written English.
You can use it when you want to describe something that is important and should be regarded with considerable seriousness. Example sentence: The environmental effects of the oil spill are of significant concern.
Zoonotic diseases continue to be of significant concern for public health.
Other people's privacy will be of significant concern, but will not stop the spread.
Its finances have previously been said to be of "significant concern" due, in part, to the increased cost of the new Stoke hospital, which was built under a private finance initiative.
Human failures in the performance of PHA and LOPA studies should be of significant concern to practitioners as such studies are difficult and time-consuming activities that place significant demands on participants, which increases the chance that errors will be made.
Therefore, the use of methanol may not be of significant concern for the patients' health although more comprehensive toxicity testing would be necessary for implementation of this polymer.
Yet if reflective of a true doubling of risk, this finding would be of significant concern for life-threatening events such as myocardial infarction or sepsis.
Changes to CRP concentration reported during the present study demonstrate that there was an increased inflammatory response post surgery, although clinically these may not be of significant concerns as all results are within the normal clinical reference range.
A blogger in Tehran said recent news was of significant concern to the country's online community.
"With regard to treatment of asylum-seekers, the overuse of restraints, such as at J.F.K., and the frequency of negative, and at times hostile, attitudes towards asylum-seekers is of significant concern," the report said.
The Australian Labor party's immigration spokesman, Richard Marles, said "the PNG supreme court's ruling that the detention of asylum seekers at the Manus Island facility is illegal is of significant concern to Labor".
