Be careful not to ingest chlorinated swimming pool water, and especially be careful that your children don’t.

Haloacetic acids form as a by product of chlorinated water.  They are possibly quite dangerous and might be associated with some birth defects and some cancers.

The journal Environmental Science & Technology reports that haloacetic acids (HAAs) can be found in urine of of people swimming in just thirty min.  after swimming in the water.

Of course chlorine also makes it safer to swim, I think the best course would be to make sure you don’t swallow any water and if you have young children maybe it would be better to keep them out of heavily chlorinated pools until you are certain they understand that they should not swallow any of the water.