Is there a relationship between a LD50 and an ADE

No. The LD50, which means lethal dose fifty percent, is a single-dose acute study at which the dose causes a 50% death rate in the test animals (usually rats). On the other hand, the ADE (acceptable daily exposure) value is the estimated dose that is unlikely to cause an adverse effect if an individual is exposed to the API by any route, at or below this dose every day for a lifetime. In other words, it's a chronic, repeat dose.

According to the EMA's  "Questions and answers on implementation of risk based prevention of cross contamination in production and ‘Guideline on setting health based exposure limits for use in risk identification in the manufacture of different medicinal products in shared facilities’ (EMA/CHMP/CVMP/SWP/169430/2012)" the use of a LD50 to establish health-based exposure limits in not acceptable.