With growing concern over the presence of BPA in canned goods, the safety of canning lids used for home processing is also being questioned. From Alan Majka of the UMaine Cooperative Extension:

I’ve received quite a few questions from consumers who are fearful of BPA leaching from canning lids into food so I was surprised when a caller this morning was concerned that Golden Harvest lids she recently purchased did not have a white coating like the Ball and Kerr lids she purchased previously. She was concerned that acidic foods may corrode the lid.

I did a web search and called Jarden Home Products to learn the following:

• Jarden makes all Ball, Kerr and Golden Harvest lids at the same plant in Muncie, Indiana. In fact, someone purporting to be a production line supervisor posted that the lids are even made on the same line.
• The only difference between the lids with white and clear coatings is the color added to the white linings.
• All Jarden lids have the following layers applied to the metal lid:

1. modified epoxy (contains small amount of BPA)
2. tin plated steel
3. modified vinyl
4. another layer of modified epoxy
5. red plastisol

• Due to consumer demand, Jarden is working on a BPA alternative, but it must undergo testing prior to approval.
• Canned food stored in upright jars is usually not in contact with the food for prolonged periods of time.
• A consumer would need to consume tens of thousands of jars of home canned food to exceed the government’s safety guidelines for BPA.
• The current reusable BPA alternative made by Tat[t]ler may have other unsafe compounds like formaldehyde and are not approved by the USDA.
• Other brands of two-piece lids are made in China.

Additional comments from Kelly Cullen, PhD in Agricultural Economics, UNH:

There is a small amount of BPA in canning lids (and most steel canned food — yikes!). Luckily, with home canning, we leave “head room”, so the food doesn’t actually come into contact with the BPA. The risk is minimal. Consumers are demanding BPA-free lids, which should hopefully come on the market in the next year or two. In the meantime, rest assured that the BPA in home canned food is less than that in most canned foods, and most microwave-in-bag foods. The quality of the produce is usually much better too!

Update 8.10.12: More on “Home Canning, BPA-Free” by Linda Ziedrich

This is part of a series of posts following the Master Food Preserver Program offered by the University of Maine Cooperative Extension. A version of this post appears at Seacoast Eat Local.