CTS = California Teacher Study; Q2 = Quintile 2; Q3 = Quintile 3.The study authors collapsed the lower (Q2 and Q3 chloroprene quartiles) into the referent population (Q1) for HR comparison purposes when a larger portion of the study participants had same concentration value; The test for trend for chloroprene was statistically elevated at p<0.04. In figure 1, authors indicated that 71% of women in the CTS had exposure levels of "zero"; the minimum detectable value was ~1E-9 µg/m3 and maximum detectable value was ~1E-2 µg/m3.