Potato blight and anencephalus in Scotland.

The theory has recently been put forward by Renwick (1972a) that anencephalus and spina bifida are caused by exposure early in pregnancy to potatoes which are affected by blight or are imperfect for other reasons. In support of this, a temporal correlation was claimed to exist between the severity of blight and the frequency of anencephalus, largely because of a strong correlation between the anencephalic stillbirth rate in Scotland and potato blight severity in the west of Scotland over the years 1946-55. Because only a small proportion of potatoes cultivated in Scotland are grown in the west (leading article, 1972), it is improbable that many of the anencephalic fetuses included in the analysis, particularly those in the east and north of Scotland, could have been exposed to any constituents of potatoes grown in the west. A more appropriate and refined analysis of Scottish data has therefore been attempted in the same period, using some unpublished data relating to a more recent period.