Hyperactivity and impaired learning ability have been reported for Rhesus monkey infants
exposed to different Aroclors in utero and during lactation (Bowman and coworkers, see
Section 5.2.2.5). The lowest dose studied (0.5 ppm Aroclor 1248 in the diet given to the
dams), caused hyperactivity in their infants. The authors estimated the weekly intake for
the mothers to be about 0.04 mg/kg, resulting in 6 μg/kg b.w. and day which, thus,
represents a LOAEL (lowest observed adverse effect level).
The validity of these studies has been questioned. However, the experiments were
performed with several cohorts of animals, although the number of animals in each cohort
was rather limited, i.e. 3-5 animals plus controls. The outcome in all the studies was
similar, i.e. an increase in behavioural activity. Studies of this type in monkeys have not
been performed by other laboratories, but supportive data are available from studies in
rats, mice and quails (for review, see Tilson et al. 1990).