Large dust grains at high redshifts: gray extinction at cosmological distances or dark energy?

Recent evidences show a non negligible amount of large cosmic dust with radius greater than 5 micron. Dust population never taken in consideration before. The question is: could this dust have some cosmological implication? From the study of Supernovae Type Ia which led to add the contribution of dark energy to the cosmological model and winning a Nobel prize, we tried to estimate an upper limit to the abundance of this population of dust and we compare it to the cosmological dust production. Moreover, we estimated the detectability of this population comparing it with that of galactic type dust which have radius less than half micron.