Concentration (ppm) Postnatal Day 1 Postnatal Day 4 Postnatal Day 7 Postnatal Day 14 Postnatal Day 20 No. Body Weight (g) Weight Relative to Controls (%) No. Body Weight (g) Weight Relative to Controls (%) Body Weight (g) Weight Relative to Controls (%) Body Weight (g) Weight Relative to Controls (%) Body Weight (g) Weight Relative to t Controls (%) Male 0 39 5.8 10 8.8 13.5 25.7 35.0 250 30 5.9 102 10 9.0 102 13.6 101 26.2 102 35.8 102 500 33 6.0 103 10 8.6 98 13.0 96 25.1 98 34.7 99 1,000 31 5.8 100 10 8.4 96 13.0 96 24.9 97 34.5 99 2,000 38 5.8 100 10 8.8 100 12.9 96 24.6 96 31.6** 90 4,000 27 5.3** 91 10 7.5** 85 10.4** 77 16.8** 65 19.8** 57 Female 0 23 5.4 10 8.2 12.7 24.7 33.6 250 34 5.6 104 10 8.5 104 12.9 102 24.7 100 33.9 101 500 32 5.4 100 10 8.2 100 12.7 100 25.0 101 33.6 100 1,000 40 5.5 102 10 8.0 98 12.4 98 24.2 98 32.7 97 2,000 49 5.3 98 10 8.2 100 12.4 98 23.7 96 30.3** 90 4,000 31 5.0** 93 10 7.3* 89 9.9** 78 16.1** 65 18.8** 56