Further, rodents are of limited value in assessing the neurobehavioural
effects, because the neurological effects (e.g., tremor, gait disorders) seen in primates
are often preceded or accompanied by psychological symptoms (e.g., irritability, emotional
lability), which are not apparent in rodents. The only primate study is of limited
use in a quantitative risk assessment because only one dose group was studied in a
small number of animals and the manganese content in the basal diet was not
provided