"formidable concern" is correct and usable in written English.
This expression is generally used to describe a difficult or daunting problem or obstacle. Example sentence: Our environmental challenge is a formidable concern that must be addressed immediately.
She observed that 'there were a number of "pretty formidable" ethical concerns in allowing future trials to go ahead' (Skatsson 2002, 1).
Nevertheless, we will argue that, in the domain of PCC, PB runs up against formidable competing concerns.
And the further along we find ourselves, the more formidable are the concerns that we encounter.
One, touched on by the commission, concerns GE Capital, a formidable operator in aircraft leasing.
But in that effort, the companies face formidable opposition from other energy concerns and trade groups that are fighting against any limits.
A formidable array of forces is concerned about the way the settlement companies solicit consumers and negotiate lower payments on their debts.
A new wave of interest in West has resulted in a number of books concerned with her formidable feminism, her games with what she would never have wished to call "gender," and her enduring status in the American pop pantheon.
In a letter sent to NSABP and University of Pittsburgh officials yesterday, NCI officials explained that "the numerous scientific concerns... are sufficiently formidable that the NCI will not commit to the funding of this particular trial".
For someone bent on keeping the planet as a going concern, the Nature Conservancy is a formidable place to be.
Staphylococcus aureus (S. aureus) infections in both man and domestic livestock present growing and formidable global challenges for human and animal health concerns.
