Background:While in the adult Al intoxication requires high dosages, little is known on the threshold level of Al toxicity in the young.Methods:Weaning rats were fed for 90 days ore of four diets differing by their content in Ca (7.5 vs <0.5g/<g diet)(Ca +/-) and Al (10.6 vs 8.4 mg/kg)(Al +/-); Al supplementation was 30% above the standard level of diet. Ca and Al levels were measured in liver, bone (femur), and brain.Results:Ca- had a significant negative effect on growth which was further reduced by Al+; in Ca sufficient/Al+ animals, Al concentrations were significantly increased in bone and brain and tended to increase in liver; Ca decreases observed in these three organs were only significant in brain. Ca deficiency further enhanced the Al deposit in bone at both levels of Al intakes, and reduced Ca concentrations in these three organs in Al+ animals; in Ca-/Al- animals, the decrease in Ca displayed in the three tissues reached a significant level in brain.Conclusions:This study suggests that in the growing subject the side effects of small variations of Al intake can be enhanced when they are combined with other mineral imbalances.