"perilous levels" is correct and usable in written English.
It is typically used to describe a dangerous or risky situation, such as "He had reached perilous levels of mental fatigue after the intense exam session."
As happened in Ireland, the expense can drive government debt to perilous levels.
His fate has weighed heavily on Mr. Tohti and increased his already perilous levels of garrulousness.
But the importance of St. Ann's has not shielded it from a long, steady decline that has reached perilous levels.
Early this year, as stocks fell to perilous levels, international grain prices doubled or even tripled, threatening as many as 100 million people with malnutrition.
He returned to the NICU at Beth Israel Deaconess Medical Center under Martin's care; his blood pressure again fell to perilous levels, and he required infusions of dopamine.
Several are owned by post-Soviet oligarchs or carpetbagging Americans, and some are burdened with perilous levels of debt.Those foreign owners are not generally popular among English fans.
Breeding and release programs began in 1965 and have successfully brought seven of the eight endangered subspecies up to less perilous population levels.
Conditions remain perilous, as water levels are still high in many areas, and food and drinking water are scarce.
Not so, notes the eminent usagist Jacques Barzun from his San Antonio house of intellect: "To walk a tight wire at the 14th floor level is perilous and not parlous.
* A balance sheet should be included in every report, because ignoring debt levels can be perilous.
Related story: "Perilous Gifts ".
