Surprise and disappointment accompanied the recent publication of country by country test results from the "Progress in International Reading Literacy Study" (PIRLS) and the "Trends in International Mathematics and Science Study" (TIMSS) when Australian children unexpectedly performed poorly.
In the PIRLS test our children rated 27 out of the 49 countries tested and in the TIMMS they performed a little better at 19th, but were still well below the top five countries - Singapore, Korea, Hong Kong, Taiwan and Japan.
New Zealand children also disappointed; while achieving better in reading performance they rated lower than Australian children in mathematics.
When interviewed about these results, the Minister for Education, Peter Garrett, obfuscated and commentators pontificated.
Academics speculated on the need to improve the selection process and training of teachers, union officials expressed the view the poor performance was a consequence of teachers being underpaid and the Prime Minister announced that Australian schoolchildren will be in the top five in the international league table by 2025.
Clearly this is a complex issue and none of the experts can explain convincingly why Australian children are behind those in many developed and developing countries. Perhaps there are multiple causes, but one issue not canvassed is the possibility it is not due to the school system or poor teaching, but is an inherent problem in the intellectual performance of our children.
The World Health Organisation states categorically that the "commonest global cause of preventable loss of intellectual performance is nutritional iodine deficiency".
Iodine is an essential micronutrient required for normal thyroid function. Moderate to severe iodine deficiency during pregnancy can result in the children born suffering from an irreversible loss of 10 to 15 IQ points.
Added to that are the results from new clinical trials in New Zealand where children having a similar degree of iodine deficiency to Australian children significantly improved school performance in IQ testing after being given an iodine supplement. But iodine supplementation during childhood will not reverse the loss of IQ from iodine deficiency during pregnancy.
Iodine deficiency is not simply a consequence of poverty and poor nutrition confined to the developing world. Work practice changes in the dairy industry in Australia over the past two decades have resulted in a decrease in iodine content in milk and dairy products, and coupled with the reluctance of consumers to purchase iodised salt has seen iodine deficiency appear as a significant public health problem here.
This situation has been compounded by the reluctance of the local food industry to use iodised salt in food manufacturing and processing.
A national survey of schoolchildren in 2003-04 confirmed our suspicions that mild iodine deficiency had re-emerged in Australia after an absence of almost half a century, which has been confirmed in subsequent studies.
What is most worrying is that it is not only children who are iodine deficient. More recent surveys have shown that pregnant women are only getting about half the recommended daily intake of iodine.
Does this add up to iodine deficiency being one of the causes for Australian children falling behind so many other countries in the basics of reading and mathematics? Who knows?
It would be naive to believe iodine deficiency was the sole cause of poor scholastic performance in our children, but it may well be a significant contributory factor.
Countries performing best in mathematics - Singapore, Korea, Hong Kong, Taiwan and Japan - have diets rich in iodine.
This is not proof that iodine intake is the critical determinant of intellectual performance in these countries, however, until we ensure that the most vulnerable in our population, namely pregnant women and growing children, are getting sufficient amounts of iodine in their diet we can go on speculating and blaming all we like, but we cannot be sure that the brains of our children are being primed to achieve their genetic potential.
Food Standards Australia New Zealand has responded recently by mandating that all salt added in the baking of bread must be iodised.
While this will improve iodine intake, it is too early to know if it will remedy the deficiency in children and we know that it is insufficient to fix the problem in pregnant women. This needs to be addressed as a matter of some urgency. Until we eliminate the scourge of iodine deficiency from Australia it is likely that the intellectual performances of current and future generations will decline further when compared with countries where iodine nutrition is optimal.
While implementation of the Gonski recommendations appears a long way off there is something we can do now at very little cost.
Cres Eastman is professor of medicine at Sydney Medical School and is the Asia Pacific Regional Co-ordinator International Council for Control of Iodine Deficiency Disorders.