Many canned food containers are lined with a very thin layer of plastic to prevent the metal can from contaminating the food. However, more often than not these plastic linings contain Bisphenol-A (BPA), associated with a number of concerning health problems which I covered in a previous post.
I decided to do some research and ask some of the main UK supermarkets and organic companies whether their food cans contain BPA and these were the results:
As you can see BPA is pretty much used in most cans, whilst remaining within the EU prescribed limits. Suma helpfully pointed me towards the Ethical Shopping guide to tinned tomatoes that further enlightens us on the topic:
Toxic tin linings & Toxic BPA alternatives
Bisphenol A (BPA) is an endocrine-disrupting chemical, meaning that is has potentially deleterious effects on reproduction and brain development. It is primarily used in the production of polycarbonate plastics and epoxy resins, which have many uses, from CDs and medical devices to impact-resistant safety equipment and dental sealants. The concern for many consumers around BPA is its role in food cans, bottle tops and jar lids, and the potential leakage of BPA into the food and drink later ingested by humans. In 2015 the European Food Safety Authority (EFSA) published the results of a re-evaluation of BPA carried out by one of its expert panels. This review found that BPA “poses no heath risks to consumers because current exposure to the chemical is too low to cause harm.”
However, the EFSA also significantly lowered the estimated safe level (tolerable daily intake or TDI) to 4 micrograms per kilogram of body weight, although this is temporary pending the outcome of a long-term study into the pre- and postnatal effects of BPA exposure. The EFSA’s study found that public exposure to BPA is “well below” the new TDI of 4µg/kg of body weight per day, with the highest estimated exposure being 3-5 times lower than the new TDI. Dietary exposure is highest among infants and toddlers, given their higher food consumption per kilo of bodyweight, but this is still more than 4 times below the new TDI. A person would have to ingest more than 400µg of BPA per kg of body weight per day to cause adverse kidney and liver effects. However, the EFSA said that effects of BPA on the reproductive, nervous, immune, metabolic and cardiovascular systems, as well as in the development of cancer “are not considered likely at present but they could not be excluded.”
However, choosing BPA-free packaging does not necessarily mean consumers are avoiding potentially harmful chemicals. A recent study by a consortium of North American non-profit organisations tested 192 cans from a range of companies and found four coating types besides BPA in use: acrylic resins, oleoresin, polyester resins and polyvinyl chloride (PVC) copolymers. The report described these as “regrettable substitute[s]” several of these are known or potential carcinogens, including PVC and polystyrene: “We know very little about the additives used in these compounds to give them the properties that make them stable and effective can linings. Our research does demonstrate that there are multiple formulations of most of these compounds, but there is no way to determine the specific chemicals used or how they are produced … the lack of safety data and unknown additives mean we have no reliable data attesting to the safety of [several of] these compounds.”
Canned vs. Dried: What is more energy efficient?
I also had a second motive for contacting all these companies. I wanted to find out what is more energy intensive: soaking dried pulses overnight and then boiling them for an hour (or more!) at home, or buying them ready canned? It turns out all companies use more or less the same process: The pulses are imported in their dried form, in some cases dehydrated again and then boiled until soft. After being canned they go through another heat process at a very high temperature to sterilise and finish off the cooking process. (Note: Plastic lined BPA cans containing food are heated above 100 degrees.)
It is clear that buying the dried pulses, soaking them overnight and then boiling them up for an hour or more is far less energy intensive and healthier than canned pulses:
- Dried pulses are lighter and less bulky to transport so far lower carbon cost
- Can be bought loose and package free
- Don’t contain BPA
- To save time they can be cooked in bulk and frozen where they retain the majority of their nutritional value for up to 6 months
- Dried pulses are three times cheaper than canned pulses
Essentially it’s up to you to judge whether you care or don’t care about the potential threat a small amount of BPA has on your health. For some brands you can look out for the “BPA-free” symbol, although we know worryingly little about the substitute materials used.
Best option for health & environment: buy the products fresh or dried, or alternatively in glass jars to avoid plastic.