1.1 ,This guide describes the procedures for obtaining and interpreting data associated with a direct health status assessment for mammalian receptors at chemically contaminated terrestrial sites where ERA work is either scheduled or ongoing, and irrespective of the number and type of chemicals that may be present. Through reviewing sperm features, the RSA method reports on the reproductive health of male rodents in their natural environmental settings, with these animals serving as surrogates for other (and larger) site mammals (4).