On an intuitive level, it isn't surprising that a chemical so similar to BPA that it could be an "easy" substitute would in fact also share similar harmful effects.
There are early rumblings (e.g. http://www.ars.usda.gov/is/pr/2009/090415.htm ) that there might be something similar going on with the replacement of trans-fats with palm oil. Palm oil behaves similarly to trans-fats, which makes it attractive to industry, but then it isn't too surprising that those same similarities might also make it similarly unhealthy.
> On an intuitive level, it isn't surprising that a chemical so similar to BPA that it could be an "easy" substitute would in fact also share similar harmful effects.
Don't rely on intuition for toxicology. If there's one field where there's a strong lack of Science (and I mean predictive Science), that's this one. There are tons of chemical compounds that have no severe tox effects, but add a couple of carbons in the chain and you can get toxicity. Or, take chirality for example. The same exact chemical formula, but the spatial arrangement being the mirror of each other's. This caused major issues back in the 20th century, when some drugs were synthesized without chiral specificity, and led to one chiral version being harmless and effective to improve a certain condition, and the other chiral version attacking the central nervous system.
> There are tons of chemical compounds that have no severe tox effects, but add a couple of carbons in the chain and you can get toxicity.
Your point not to rely on intuition is a good one, but I think that's not quite what the GP was doing. That is, I think the claim wasn't that a chemically similar compound should behave similarly, but rather that a behaviourally similar (in some ways) compound should behave similarly (in other ways)—stated which way it is almost a tautology, no?
There are early rumblings (e.g. http://www.ars.usda.gov/is/pr/2009/090415.htm ) that there might be something similar going on with the replacement of trans-fats with palm oil. Palm oil behaves similarly to trans-fats, which makes it attractive to industry, but then it isn't too surprising that those same similarities might also make it similarly unhealthy.