Dear crabapple-ga
I do not know where in the world you are located, but each country has
different regulations for its food production industry and therefore
cans can be made of slightly different materials from country to
country. However, I have found some reports which you may wish to read
in greater depth. Their conclusions are that the cans are safe but in
one case further scientific research is required.
The canned food process has three stages where contamination may take
place:
The canning process and storage.
Chemical migration from the can to the food.
Opening the can.
The canning process and storage:
Spores of Clostridium botulinum if not destroyed in the canning
process can produce a toxin which if consumed can cause botulism, a
serious foodborne illness.
See The Food and Drug Administration (FDA) Center for Food Safety and
Applied Nutrition
http://vm.cfsan.fda.gov/~dms/a2z-c.html
Chemical migration from the can to the food. (This is the main point
of your question)
Lead has been removed from cans and the amount of tin has been
reduced.
“The U.S. canned food industry, which began phasing out the use of
lead-soldered cans in 1979, stopped using lead-soldered cans in 1991.
In 1995, the Food and Drug Administration issued a final rule
prohibiting the use of lead solder in all food cans, including
imported products.
Metal cans, which are made of sheet steel -- sometimes with a coating
of tin -- are now welded closed at the seams. The inside of the can
may also have an enamel or vinyl protective coating.”
http://www.fsis.usda.gov/OA/pubs/meatpack.htm
In the UK, tin content is restricted to 200 milligrams per kilogram.
“No long-term health effects are associated with consuming tin. But it
can cause stomach upsets such as nausea, vomiting, diarrhoea,
abdominal cramps and bloating in some sensitive people at levels above
200 milligrams per kilogram”
“Of the canned fruit and vegetables and tomato-based products tested,
99.5% contained tin concentrations below 200 milligrams per kilogram
(mg/kg). This is the maximum legal amount of tin that can be present
in canned foods.
Most of our dietary intake of tin (94%) comes from canned fruit and
vegetables.
http://www.foodlaw.rdg.ac.uk/news/uk-02090.htm
Recently, concern has been raised over the protective coating inside
the cans.
In the UK the Food Standards agency examined polymeric coatings and
their effect on food.
Bisphenol A in canned food was examined “because of the uncertainties
that exist in the scientific understanding of potential endocrine
effects of this substance. “
The conclusion was:
“…..on present evidence they conclude that the levels of BPA
identified in canned foods analysed in this survey are unlikely to be
of concern to health, and that there is no reason for consumers to
change their source of foodstuffs as a result of these findings. “
However, you may wish to read the report yourself and make your own
conclusions.
http://www.foodstandards.gov.uk/science/surveillance/fsis-2001/bisphenols
http://archive.food.gov.uk/consultations/bisphen_let.htm
A response to the survey which is interesting reading, is at
http://www.wwf.org.uk/filelibrary/pdf/wwf_response_to_fsa.pdf
Another examination looked at terephthalic and isophthalic acids.
“Terephthalic and isophthalic acids migrated into food from the
coatings of 12 out of 28 samples of cans.
The Committee on Toxicity advises that these levels of terephthalic
and isophthalic acids are not of concern for public health based on
available information, and recommends further toxicological work on
these substances to see if they have endocrine disruptor activity.”
http://www.foodstandards.gov.uk/science/surveillance/fsis-2000/7phthal
UK Department of Health
http://doh.gov.uk/com/tpa.htm
Opening the can.
The only concerns that I could identify was the physical contamination
of the food products due to dirty metal shavings falling in the food.
All reliable sources stress the cleanliness and effectiveness of the
can opener. There are now many can openers which are advertised as
‘metal shavings’ free.
“Can openers must be thoroughly cleaned manually using a brush with a
detergent in warm water and sanitized after each use period. The
cutting mechanism must be replaced or repaired when metal shavings are
produced in the can opening operation. Can opener holders should be
cleaned as necessary.”
Naval Preventative Medicine
http://forum.nomi.med.navy.mil/cd/CD013/DATA/operationalmed/Manuals/food/manual/section2/1-15.htm
I trust this answers your question crabapple-ga. If it does not, or
the answer is unclear, then please ask for clarification of this
research and I shall respond to the clarification request as soon as I
receive it.
Thank you
answerfinder-ga
"canned food" contamination
://www.google.com/search?q=%22canned+food%22+contamination&hl=en&lr=&ie=UTF-8&oe=UTF-8&start=0&sa=N
"canned food" "chemical migration"
://www.google.com/search?q=%22canned+food%22+%22chemical+migration%22&hl=en&lr=&ie=UTF-8&oe=UTF-8&start=0&sa=N
"can opener" "metal shavings"
://www.google.com/search?q=%22can+opener%22+%22metal+shavings%22&hl=en&lr=&ie=UTF-8&oe=UTF-8&start=0&sa=N |
