Prospective investigation of the intellectual development at the age of 6-7 years till age 15-16 years among persons exposed in utero following the Chernobyl accident.

250 persons from Belarus exposed in utero following the Chernobyl accident and a control group of 250 persons from non- and slightly contaminated regions. Рsychological examinations were performed among persons of both groups at the age 6-7 years, 11-12 years, and 16 years as well as dosimetrical analysis.

Mean antenatal internal dose to thyroid gland arising from the intake of 131I among persons of exposed group is 390±550 mGy (maximal dose - 4100 mGy), in control group - 35±65 mGy. Mean antenatal external dose among persons of exposed group is 10±13 mGy. At the age of 6-7 years the persons in the exposed group had a mean Full Scale IQ lower than the control group (89.6±10.2 vs 92.1±10.5, P=0.007). At the age of 11-12 years there was no statistically significant difference between the two groups (94.3±10.4 vs 95.8±10.9, P=0.117). Positive dynamics of intellectual development in persons of both groups has been observed up to age of 16 years (98.7±10.2 и 99.5 ± 10.5, P=0.171).

No statistically significant correlation was found in exposed group between individual thyroid dose as well as individual antenatal external dose and IQ at the different ages.