"exact causes" is a grammatically correct phrase that can be used in written English.
For example, "Scientists have not yet determined the exact causes of global warming."
An investigation into the exact causes is ongoing.
But exact causes of longevity remain a mystery.
"The exact causes are unknown," said Dr. Gilles Lavigne.
The economists don't pretend to know the exact causes.
Though sorting out the exact causes is complicated, trends are clear.
Dr. Lauer said most of the deaths were likely to be heart related, though exact causes were not available.
You can see why it would be tricky to pin down the exact causes of drunken antics.
"The exact causes of death haven't been determined," said Giuseppina Gabriele, the city supervisor of services to the homeless.
The exact causes of breast cancer are largely unknown, but both environmental and genetic factors are involved.
Although insufficient protein and calories have been blamed, studies have not been able to pinpoint the exact causes.
Although experts are uncertain of the exact causes, the progress follows a period after the 1970s when childhood obesity trebled in the US.
