Ask A Scientist General Science Archive

name         Tom K.
status       other
age          60s

Question -   Frozen seafood purchased at a supermarket and stored in
my freezer  in a plastic zip-lok type bag gets a moth-ball odor after a
short while. The temperature in the freezer is correct and the bags are
securely closed. Fresh bread bagged and frozen does the same thing. Could
benzene or plasticizers or other hydrocarbon aromatics be leaching from
the bags into the food? Is the food safe to eat?
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I am not sure what you are smelling but off-gassing of should be quite low.
I know the amount has been measured for most plastics and reported years
ago.I believe it was by a group commissioned bt the national acaemies of
science. I doubt any risk unless the bags are heated. 

Pf
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Moth-ball-like chemicals go thru poly-ethylene bags very easily.  Oxygen, too.
Aluminum foil would stop it, especially if it's 3 wraps thick and the edges sealed with frozen water.
(And to keep the aluminum off the fish, white freezer paper inside that.)
Too much work, but try it, see if the odor forms inside anyway.


If the odor was from the bag, you'd be able to smell it before the bag touched the fish.
It might be eliminated by leaving the bag out a week before use.  Quicker if warmer.
No need to reach 100C, bag might melt.  Microwave to roughly 80C in water bath, should drag out any plausible plasticizers.
Hard to believe polyethylene needs plasticizers anyway, it's very flexible that thin.


I've seen refrigerators smell vaguely like that.   What did it smell like the last time you saw it defrosting?
Is it old enough to have a DuPont's Freon (TM)-and-oil leak?
But I really don't know where that smell comes from.


Jim Swenson
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