Best way to store seed!

On the recommendation from a lot of folks, I have been storing my seed collection in a one gallon zip lock bag in the freezer. Each variety of seed is also still in the original paper packets the seed shipped in from the vendors.

I have ordered and received about twenty heirloom tomato varieties that really interest me for their traits of production, size, taste, and appearance. I purchased a supply of the little miniature zip lock type bags yesterday to both store (makes it easy to count the seeds) and mail seed to folks who may want to trade in the future. Has anyone had any bad experiences using the little self sealing bags. I guess my biggest concern is chemicals used in the manufacturing process of the plastic to keep it flexible and keep it slick enough to pass through the machinery which makes the bags. Has anyone had any negative effect on their seeds from those chemicals?

Ted