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ABsTRAcr The effect of a dose of alcohol on the kinetics of mandelic acid excretion in four volunteers exposed to 220 mg/m3 styrene has been investigated under controlled exposure chamber conditions. Ethanol inhibited the excretion of mandelic acid, so that the peak excretion was delayed from the end of the exposure period until three hours afterwards. One hour after administration of ethanol blood mandelic acid concentrations were 56% of the levels found during the alcohol-free control exposure, and this was paralleled by a 15-fold rise in phenylethane 1,2 diol, the metabolic precursor of mandelic acid. It is suggested that the inhibition of the oxidation of this diol is related to the change in NAD+/NADH ratio produced by ethanol metabolism. The implications of this ethanol effect on the interpretation of urinary mandelic acid excretion when monitoring workers exposed to styrene are discussed.It is now established that monitoring workers exposed to styrene vapour is best accomplished by measuring the excretion of mandelic acid in the urine.1-5 The usefulness of mandelic acid determinations depends on the time of taking the urine sample after the end of the workshift.6 Several authors have suggested end-of-shift sampling while others have recommended next-morning samples."--In an earlier study we reported a detailed investigation of the daily excretion of mandelic acid by two technicians building glass-reinforced plastic boats under model ventilation conditions.7 Both these subjects showed maximum mandelic excretion several hours (4-8 hours) after the end of exposure. The time-lag was relatively constant for each individual and not related to level of exposure. We suggested that such a time lag in maximum excretion rates required a modification of sampling strategy. Our report of this time-lag in excretion has caused some controversy. Guillemin and Bauer"2 reviewed those papers reporting a time-lag and have contrasted these reports with their experience that experiments with volunteers under controlled exposure-chamber conditions show that maximum excretion occurs at or near the end of exposure. Since their publication we have confirmed that under controlled exposure chamber conditions maximum excretion of mandelic Received 15 March 1982 Acccepted 7 May 1982 acid does occur at the end of the exposure period. On the other hand, we have also found that a significant proportion of industrial workers in the glass-reinforced plastic boat industry that we have studied in detail show a delayed excretion of mandelic acid. This difference in excretion kinetics between volunteers under controlled conditions, and workers building glass-reinforced plastic boats requires explanation. Among the factors considered was the effect of the ingestion of alcohol. Alcohol affects the metabolism of xylene, toluene, and trichloroethylene."3-16 In this study we have investigated the effect of alcohol ingestion on the excretion of mandelic acid by volunteers under controlled exposure conditions.

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A preparatively convenient and mild method for modified Khand cycloadditions is described; vinyl esters are employed as the olefinic reaction partner to provide cyclopentenone products more normally obtained with ethylene.

As a basis for embryo cryostorage research, information on relative toxicities of cryoprotectants is of key importance. Both morulae and tail-bud-stage embryos of red drum (Sciaenops ocellatus) were exposed to cryoprotectant solutions for 20 min at room temperature. Artificial seawater (ASW) at 30-32%o was used as a medium. Embryos were exposed to solutions in a one-step addition. Toxicity was evaluated in terms of percentage hatch and 40-h survival. Maximum concentrations tolerated by morulae without significant reduction in hatch and survival were 1 M glycerol, 2 M dimethyl sulfoxide (DMSO), 2 M methanol, 0.5 M sucrose, and 95%o ASW. Ethylene glycol was toxic to morulae even at 0.25 M. Tail-bud embryos were more resistant, with maximum innocuous concentrations being 1 M glycerol, 2 M DMSO, 2 M ethylene glycol, 2 M methanol, 0.5 M sucrose, and 95%o ASW. Serial addition and dilution of 95%o ASW offered no advantage over a direct plunge and rinse. Maximum harmless concentrations may not afford adequate cryoprotection. Reduced hatch and survival may be a result of osmotic shock or ionic imbalance rather than a direct consequence of toxicity. Preliminary cryopreservation experiments did not achieve survival of embryos cooled to subzero temperatures.