My8 month old DD is fed partly on donated breastmilk as I'm unable to produce any. The latest kind donation unfortunately has been frozen in ordinary freezer bags rather than breast milk storage bags (which are pre-sterilised and BPA-free). Would it be really stupid to use it anyway? I have no doubt it was hygienically and carefully expressed and frozen because the lady was genuinely dismayed and unaware that it's not recommended, and had used some to feed her own DD (who wasn't ill as a result of the non-sterility) It seems such a shame to throw it away - is BPA likely to be a problem for a one-off like this, especially as it was frozen as soon as it was expressed?