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How to Can Food BPA-Free: Toxins in Mason Jar Canning Lids

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Many mason jar lids contain BPA, a plasticizer, which acts like estrogen in the body, disrupting normal hormone regulation.

Many mason jar lids contain BPA, a plasticizer, which acts like estrogen in the body, disrupting normal hormone regulation.

Mason Jar Lids and BPA

Many home canning jars contain BPA in the lining of the lid. After all the hard work of gardening and preserving your own healthy food, it's a shame to store it in a container that contaminates the food with BPA. The term BPA-free isn't necessarily better, but there are options for home canning, such as using Weck jars, where BPA is avoided while also considering recommended food safety guidelines. I want to help others consider a new or different view, but always be mindful that any action taken based on these opinions is the reader's responsibility.

Bisphenol A chemical structure

Bisphenol A chemical structure

Why Is BPA a Problem?

BPA, or bisphenol A, is a compound present in plastic products such as water bottles, paper receipts, and the lining of food cans and mason jar lids. As BPA leaches out of these plastic products and is consumed, it mimics estrogen in the body. Hormones are normally secreted into the bloodstream by a system of glands known as the endocrine system. The addition of hormone-mimicking compounds disrupts this regulated process and is linked to negative effects on development as well as the neurological, reproductive and immune systems.

The U.S. National Institute of Health states that animal studies show a link between exposure to BPA and disorders such as early onset of puberty, breast and uterine cancer, asthma, diabetes and cardiovascular disease.

Exposure to BPA is widespread. The Center for Disease Control found, through a study in 2003-2004, that 93% of Americans six years and older have detectable levels of BPA in their urine. Eliminating continued exposure is shown to drastically reduce the amount of BPA in the body, according to a 2011 study by the Breast Cancer Fund. Minimizing BPA exposure by finding alternative choices in everyday products will reduce these effects significantly. BPA-free home canning is one step in this direction.

Is BPA-Free Better?

Now that BPA has gotten a bad rapport, BPA-free products are popping up. This is good news and bad. The bad news being that unknown chemicals may be replacing BPA in products. The general purpose of BPA is to make plastic hard and keep metal from rusting. These needs still need to be met with plastic products and metal food containers. So, what's being used? Scientists have discovered that other compounds that leach out of plastic may have an even greater effect on estrogen in the body than BPA.

It's expected that the standard wide-mouth jar brands will soon be offering BPA-free lids for their jars. My guess is that this is a marketing scheme to subdue fears of BPA without truly lessening chemical exposure from the lid. Time will tell. The best way to avoid BPA and BPA-like chemicals is to avoid plastic and metal for food storage altogether.

Notice the glass lids with rubber rings. Let's get back to our roots and get away from BPA lined metal lids.

Notice the glass lids with rubber rings. Let's get back to our roots and get away from BPA lined metal lids.

In the U.S., the National Center for Home Food Preservation recommends using mason-type wide-mouth jars for canning: Ball and Kerr mason jars are examples. This type of jar requires new lids each time they are used. This new lid makes it easier to achieve a proper seal, reducing failure rates and food spoilage. However, these jar lids contain BPA.

In Canada and Europe, glass jars with glass lids and rubber rings are the accepted choice in home canning. Weck jars are a trusted brand that's been used for about a century. With some diligence to make sure that the reusable glass lid and rubber ring meet quality specifications year after year, these jars provide a reliable seal. Replacement rubber rings are available if needed.

How Do These Jars Work?

Weck brand is the example I'm using in this article since I am personally familiar with it. I have tried them and they worked beautifully. All components, including the rubber ring, are BPA-free.

The Weck glass jar and glass lid are sealed with a rubber ring between them. Metal clamps are used to hold the jar closed while processing, and then they are removed. The rubber ring has a tab that sticks out on one side. After processing the food, the tab will point downward, indicating a proper seal. After storage, the seal can be checked in two ways. The tab should still be pointing downward, and upon pulling the tab to open the jar, there should be a release of air as the seal is broken.

Does the Food Come in Contact With Lids During Canning?

There is quite a debate as to whether the food comes into contact with BPA in metal lids. Since there is head space to allow the jar to build up a vacuum, many believe that the food never comes into contact with the lid. However, the food is expanding inside the jar as it's heated. With boiling food, and little head space, you can imagine the popping and bubbling and condensation coming into contact with the lid and then rolling back down into the food. BPA is activated by heat and acidic conditions. Boiling hot, acidic foods are a worst-case scenario for canning and BPA contamination.

If you have any doubt, observe the food touching the lid when using a Weck jar. Look through the glass lid while canning with a boiling water bath. You'll see the activity.

Weck jars in a boiling water bath

Weck jars in a boiling water bath

Where to Buy Weck Glass Canning Jars

If you're serious about eliminating exposure to BPA through canning, then buying Weck jars is your first step.

Glass jars that have glass lids, like Weck, are more expensive than the standard wide-mouth canning jars with metal lids. They are difficult to come across secondhand but are available for sale online. Your best deal will be on eBay or possibly Amazon. I started with a small collection to experiment with and have decided to expand my collection since they worked out so well.

Justifying the Expense

Reasons to help justify the expense of Weck jars:

  • Avoiding BPA (and plastic in general) means avoiding potential negative health effects.
  • Most canned tomato products available at the grocery store are metal cans with BPA lining or jars with lids that contain BPA in the lining or lid adhesive. If you are already investing in a more expensive brand that sells tomatoes in a BPA-free container, then investing in a more expensive brand of canning jars to offset it may not be that much of a reach. Who's to say these BPA-free brands are better anyway?
  • There is less waste in materials since the lids do not need to be replaced each year.
  • If you already have a collection of mason jars, they can be repurposed to store dry goods and crafts supplies or even serve as vases.
  • Plastic lids are sold by Weck to use once the jar is opened and temporarily stored in the refrigerator (not for canning). If you ever have unused Weck jars, they can be used as general-purpose food storage containers. Food doesn't need to be in contact with the lid in this situation.
  • There are so many shapes and sizes available for every possible canning purpose.

If you still can't justify the extra expense, then see how your own organic garden can pay for itself, including the purchase of Weck canning supplies.

This content is accurate and true to the best of the author’s knowledge and does not substitute for diagnosis, prognosis, treatment, prescription, and/or dietary advice from a licensed health professional. Drugs, supplements, and natural remedies may have dangerous side effects. If pregnant or nursing, consult with a qualified provider on an individual basis. Seek immediate help if you are experiencing a medical emergency.

© 2012 Melis Ann