The limits separating values that are significantly low or significantly high are:
- Significantly low values are \( 24.37 \) cm or lower.
- Significantly high values are \( 29.01 \) cm or higher.
The adult male foot length of \( 23.9 \) cm is significantly low because it is less than \( 24.37 \) cm.
\(\boxed{\text{Significantly low values: } 24.37 \text{ cm}; \text{ Significantly high values: } 29.01 \text{ cm}; \text{ Conclusion: significantly low.}}\)