I have also included this in part in the summary as I think these papers are important.
The presence of selenium and other minerals in fish may explain why fish intake that is likely high in fluoride (eg whole fish such as sardines) is not generally associated with thyroid conditions etc.
The Chinese paper starkly demonstrates that higher iodine alone will not necessarily prevent the inhibition by excess or imbalance of fluoride of thyroid function and the induction of goiter or indeed fluorosis.
Importantly this http://www.google.com/url?sa=t&rct=j...55123115,d.Yms Chinese study of a population with both high fluoride 3mg per litre (approx) and relatively high iodine 1mg per liter (approx) in their water observed "In high iodine and high fluorine areas, the goiter and dental fluorosis rates of children aged from 8 to 12 were 29.8% and 72.98%.", which suggests that higher iodine alone may not mitigate high fluoride intake. It looks as if the picture is more complex and also involves mineral intake; likely all of the 'elements' (as in pieces of the nutritional jigsaw - no pun intended 
) need to be in place to minimise the risk of fluorosis / wider iodine / thyroid dysfunction.
Does high fluoride intake in whole marine foods have the same effect is a question I raise, as we have always associated fish intake with healthy populations. Fish would also contain important minerals such as selenium and zinc.
Fluoride apparently actively binds with selenium which interestingly may be protective against the effects of fluoride. http://www.ncbi.nlm.nih.gov/pubmed/20143719 Apparently it also bind with other minerals, so could part of the effect of fluoride be to inactivate minerals, which are often already in short supply in the western diet, but are provided in marine foods. This mechanism would in nutritional terms be a double edged sword;
- protection against excess fluoride by deactivation of fluoride by binding to minerals good.
- deactivation of important minerals that are already deficient in many diets bad.
An unreferenced comment here http://www.healthyshopping.com/OlaLoa/autism.asp by Richard A. Kunin, M.D. said interestingly
" Fluoride forms insoluble complexes with selenium. Since selenium is strongly electropositive, it combines with fluoride preferentially, with even greater avidity than calcium, magnesium, iron, zinc, sodium, potassium. The total adult body content of selenium is less than 100 mg, so little as to be vulnerable to sodium fluoride intakes of 3 to 5 mg per day, which are usual in this country because of fluoridation and fluoridated toothpaste. Consider that vital trace minerals, such as selenium, chromium and molybdenum, are ingested on average only about 50 mcg per day. Fluoride intake is 100 times more and fluoride complexes are likely to inactivate these trace minerals by rendering them insoluble--even in the presence of calcium, magnesium, boron or aluminum salts, which also bind with fluoride. Sodium fluoride, the relatively soluble fluoride used in water fluoridation, preferentially binds to the trace minerals, selenium and chromium."
This paper refers to possible links between calcium and magnesium deficiences and populations at risk of fluorosis. http://www.google.com/url?sa=t&rct=j...55123115,d.Yms