Dr. Philip M. Tierno Jr., Director of Clinical Microbiology and Immunology at the NYU Langone Medical Center, helped determine that tampons were behind toxic shock syndrome (TSS) cases in the early 1980s. Tierno blames the introduction of higher-absorbency tampons in 1978, as well as the relatively recent decision by manufacturers to recommend that tampons can be worn overnight, for increased incidences of toxic shock syndrome.[17] However, a later meta-analysis found that the absorbency and chemical composition of tampons are not directly correlated to the incidence of toxic shock syndrome, whereas oxygen and carbon dioxide content is associated more strongly.[18][19][clarification needed]