I don't know how to attach a pdf but the Jan-Feb 2020 newsletter of the Oregon State Beekeepers Association has a mention of a study by Oregon State University on page 14 on this topic -
https://orsba.org/the-bee-line-archive/.
The study is on-going so no conclusive results to report at this juncture.
Off topic, but in the same newsletter on page 1 is a small study which they did on the effect of formic acid and oxalic acid on brood which might be of interest.
Kevin