The locomotor activity of all animals was analysed in an open field. This test was performed in 45- and 90-day-old offspring separately, both groups treated with 5 and 10 mg/l of F in drinking water during pregnancy and lactation. Each 45- and 90-day-old offspring was placed in an open area of 50 × 50 × 60 cm whose floor was divided into 12 × 12 cm squares by black lines. The number of squares entered by each rat with all four paws, rearings (occasions on which the animals stood on their hind legs), groomings (face washing, forepaw licking and head stroking) and faecal boluses were scored every 5 min for 15 min. The number of squares crossed and the rearings were recorded as parameters of locomotor activity, whereas the number of groomings and the number of faecal boluses deposited were considered as parameters of emotionality [16,17]. Once each animal was removed, the open field was carefully cleaned with a damp cloth.