For information about storage time of refrigerated ebm I would suggest
reading:
Sosa, R. & Barness, L. Bacterial Growth in Refrigerated Human Milk. AJDC
1987;
  141:111-112.
In this study, "bacterial colony counts progressively decreased
throughout the five-day refrigeration period."

For information about storage time at other temperatures read:
Hamosh, M., Ellis, L.A., Pollock, D.R., Henderson, T.R., Hamosh, P.
Breastfeeding
    and the working mother: effect of time and temperature of short-term
storage on
    proteolysis, lipolysis, and bacterial growth in milk. Pediatrics
1996; 97;4:492-498.
In this report it is suggested safe to store ebm at 15 °C for 24 hours,
and at 25° C for 4 hours.

Rachel Brusseau