Postings about the potential harm of BHT and BHA have been rolling around
the FML for about a week, and yesterday Bill Gruber noted that we should
keep this debate centered around its impact on our ferret friends.  Well,
as a ferret mom, I admittedly threw out my BHT- and BHA-containing ferret
products upon first hearing that they may be carcinogenic.  I admit that it
was an emotional and subjective response on my part, because as I mentioned
on my first-ever post to the FML, I have lost pets to cancer before.  BUT I
am also getting my doctorate in biology this May, and as a biologist (and
after corresponding with Sukie -- thanks!), I did some objective research
using the ever-helpful Science Citation Index database and local university
library.
 
This is what I found about BHT (butylated hydroxytoluene) and BHA
(butylated hydroxyanisole):
 
BHA and BHT were originally added to food to retard the oxidation of fat
that leads to spoiling of food.  In high dosages, BHA has been shown to
induce tumors in the forestomach of animals.  After long-term exposure, BHT
has been shown to induce tumors in the livers of animals.  (Both BHA and
BHT were found in other studies to promote irregular cell growth in animal
livers).  Both BHA and BHT are more likely to cause tumors in animals whose
immune systems are already overloaded (i.e., animals who are already sick).
BHT and BHA are also antioxidants, and in general, antioxidants tend to
have anticarcinogenic properties.  However, any beneficial effects of BHA
and BHT are negated by the fact that BHT and BHA are carcinogenic.  In sum,
BHA and BHT are considered to be tumor promotors, but their carcinogenic
effects may not be seen unless animals are exposed to it on a long-term
basis, given high quantities of food that contain the preservatives, or
have suppressed immune systems for other reasons.
 
These are the primary references I used for this info.  These refs reviewed
a lot of other research that has been done on this topic as well.:
 
1. Iverson, F. 1995.  Phenolic antioxidants - health protection branch
studies on butylated hydroxyanisole.  Cancer Letters 93: (1) 49-54.
 
2. Kahl, R. and H. Kappus.  1993.  Toxicology of the synthetic antioxidants
BHA and BHT in comparison with the natural antioxidant vitamin-E.
Zeitschrift fr Lebensmittel-Untersuchung und-Forschung 196: (4) 329-338.
 
3. Tseng, H.H. and W.F. Huang.  1995.  Studies on the promotion of
transformation of initiated rat-liver epithelial-cell by phenobarbital,
butylated hydroxyanisole and butylated hydroxytoluene.  Journal of Food
and Drug Analysis 3: (1) 39-49.
 
So please, take this posting for what you deem it to be worth, and make
your own decisions based on an objective reading of the available data.
As for me, being a biologist, I stand by my decision to eliminate using
Marshall's and Ferretone in my fuzzie's diet after reading the original
literature.  As a ferret mom, I feel better about doing so.
 
Helen & Felicia
[Posted in FML issue 2617]