according to the Centers for Disease Control and Prevention http://www.atsdr.cdc.gov/toxfaqs/tf.asp?id=200&tid=36 ATSDR ToxFAQs™: Chlorine ATSDR ToxFAQs™: Chlorine on the CDC website http://www.atsdr.cdc.gov/toxfaqs/tf.asp?id=200&tid=36 Chlorine (CL) Chlorine (CL) http://www.atsdr.cdc.gov/toxfaqs/tf.asp?id=200&tid=36 Toxicology FAQs ToxFAQs for Chlorine ToxFAQs for Chlorine