（１）地域別の量反応関係 This increase is not uniformly distributed across the country: for example, there is no significant increase in Mogilev, Minsk City or Vitebsk. By far the greatest increase is seen in the Gomel region, from one or two cases per year to 38 in 1991, and a less obvious increase is seen in the Brest and Grodno regions.
（２）進行がんの多さ We have classified the tumours according to the World Health Organisation classification (2nd edn) and find that virtually all are papillary carcinomas (128 of 131). They are, however, relatively aggressive, as can be seen from Table 2. Fifty-five of the 131 cases showed direct extension to the perithyroid tissues and six distant metastases, mostly in the lungs. It can be seen that only about 23 per cent were less than 1 cm in diameter. One of the children has died at seven years of age and ten others are seriously ill.
