Results

There were 67 live births in Fukuoka after the incident from February 1968 to December 1977 and 18 live births in the region of Nagasaki from February 1968 to December 1971 (table 1). The probability of having a male live birth was not significantly different from that of general population. In Fukuoka, the number of live boys born after the incident exceeded girls (42 v 25), but the difference was not significant. In Nagasaki, the probability of a live boy being born did not significantly increase or decrease in any period examined, although there were more live girls born in the 11 months immediately after the incident (five girlsv one boy).

Discussion

We could not find any excess of births of girls over boys in the Yusho incident, a different result from that reported after the Seveso incident,1 2 but similar to that found in the Yucheng incident in Taiwan.3 The main difference between the Seveso and the Yusho and Yucheng incidents is the make up of the compounds exposed to. In Seveso, TCDD was the main compound causing exposure, but it was PCBs and PCDFs in Yusho and Yucheng; TCDD was not found in the contaminated rice oil.7 Therefore, there could be different mechanisms of action between TCDD and PCBs or PCDFs on the sex ratio that could explain the different results in these incidents. Mocarelli et al inferred from the Seveso incident that TCDD induces epididymal impairments or acts on an Ah receptor which is thought to mediate the effect of TCDD to change the sex ratio.2

In Seveso, exposure to TCDD before or during puberty in males was a predictive factor for producing more female offspring in later life.2 Our study period was too brief to allow us to follow up births to those who were exposed to PCBs or PCDFs before or during puberty. To clarify the effect of dioxin and dioxin-like compounds on young males with regard to their future offspring, a further investigation of sex of their offspring needs to be carried out for the Yusho victims, especially those who were younger than 19 years of age at the time of the incident.

Many journals, including the BMJ, have moved to a system of open reviewing, whereby authors know the names of reviewers of their papers. Research has shown that named reviews, although not of better quality than anonymous reviews, are not of worse quality either. Therefore in the interests of transparency, it seems fair to let authors know who has reviewed their paper. AtOccupational and Environmental Medicine we have considered the issue carefully. There are some concerns that reviewers, especially those who are more junior, might feel intimidated and not wish to make negative comments about papers submitted by senior people in the field. On the other hand, some reviewers might hide behind the cloak of anonymity to make unfair criticisms so as to reduce the chances of publication by rivals. We have decided to introduce initially a system of open reviewing if the reviewers agree explicitly. So when a reviewer is sent a paper, he or she is asked to indicate whether we can disclose their name or not when sending the authors their comments. We will be monitoring this to see how many of our reviewers are happy to be named. If it is most of them, we will move to a system of open reviewing as the norm, with a possible “opt out” clause for reviewers.