il Letter to the Editor] Incorrect Overestimates of Blood Alcohol Concentration from Breath Test Results To the Editor:

In 1982 Dubowski (1) concluded, "[T]he 2100:1 conversion tends to underestimate he actual BAC in about 86%o of the population by a mean of about 8%0, because the functional alcohol partition ratio between blood and breath in healthy adult males was found to be 2.28 x 103. ' ' In other words, from a sample of healthy men known to be "fully postabsorptive, " Dubowski concluded 86 % of the population would have actual BAC underestimated, even though there is no assurance that people in the general population are "fully postabsorptive " or that the general population consists of healthy males. These conclusions were apparently based on results presented in 1979 (2), funded by the Insurance Institute for Highway Safety. As pointed out earlier (3), 86 % underestimates are not only unrepresentative of the general population, they are also not consistent with appropriate areas under a normal error curve. Clarification of Dubowski's conclusions was made in recent estimony given for the New Jersey Supreme Court. From the Findings of Fact, ' State v. Downie, Docket No. A-167, September Term, 1988, written by Hon. P. McGann, Dubowski's testimony is reported as the following: Based on all of his studies of some 390 paired results from several hundred subjects, his experience has been that when Breathalyzer readings are converted to blood/alcohol readings using a 2100 to l ratio, in 86 % of those pairs, the converted BAC will underreport or underestimate the measured venous whole blood BAC, in the post-peak state of healthy adult males. In 2.6 percent of the pairs the supposed BAC and actual BAC turned out t