This paper comprises an updated version of the 2014 review which reported 1846 volatile organic compounds (VOCs) identified from healthy humans. In total over 900 additional VOCs have been reported since the 2014 review and the VOCs from semen have been added. The numbers of VOCs found in breath and the other bodily fluids are: blood 379, breath 1488, faeces 443, milk 290, saliva 549, semen 196, skin 623 and urine 444. Compounds were assigned CAS registry numbers and named according to a common convention where possible. The compounds have been included in a single table with the source reference(s) for each VOC, an update on our 2014 paper. VOCs have also been grouped into tables according to their chemical class or functionality to permit easy comparison. Careful use of the database is needed, as a number of the identified VOCs only have level 2—putative assignment, and only a small fraction of the reported VOCs have been validated by standards. Some clear differences are observed, for instance, a lack of esters in urine with a high number in faeces and breath. However, the lack of compounds from matrices such a semen and milk compared to breath for example could be due to the techniques used or reflect the intensity of effort e.g. there are few publications on VOCs from milk and semen compared to a large number for breath. The large number of volatiles reported from skin is partly due to the methodologies used, e.g. by collecting skin sebum (with dissolved VOCs and semi VOCs) onto glass beads or cotton pads and then heating to a high temperature to desorb VOCs. All compounds have been included as reported (unless there was a clear discrepancy between name and chemical structure), but there may be some mistaken assignations arising from the original publications, particularly for isomers. It is the authors’ intention that this work will not only be a useful database of VOCs listed in the literature but will stimulate further study of VOCs from healthy individuals; for example more work is required to confirm the identification of these VOCs adhering to the principles outlined in the metabolomics standards initiative. Establishing a list of volatiles emanating from healthy individuals and increased understanding of VOC metabolic pathways is an important step for differentiating between diseases using VOCs.

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Liposcelis bostrychophilus, whether in culture or fasting, was found to maintain the amount of its body water at nearly 66% of its fresh weight while in air of at least 60% relative humidity between temperatures of 7°C and 42°C. In these conditions intervals of body water loss reaching 1 to 2 pg alternated with recovery of the loss by the physiological absorption of water from vapor at a rate many times that of the water loss. In other conditions a loss of one-half of the body water could be survived. The time dependence of a change in the mass or the tritium content of body water was that of a single compartment from which water molecules were cleared by first-order processes, primarily diffusion, having rates in proportion to the momentary mass of body water while water entered from vapor, was metabolically produced, and some evidently was cleared by processes having rates independent of the body water mass. The physiological absorption process was seen to reach its full rate or to stop within minutes, and it was accompanied by a reduced rate of body water clearance. In any particular physical surroundings the body water mass approached a steady-state value with the half-time of the first-order clearance processes. A few measurements of these quantities, over the ranges of temperature and relative humidity, afforded accurate prediction of the recovery time or the longevity in other conditions. Key words booklouse, Liposcelis bostrychophilus, insect water relations, tritiated waterThe supplies, losses, and variations in amount of body water in a terrestrial arthropod are important factors of its physiology and its ecology that have been accounted for in only a modest number of species (Edney, '77; Wharton and Richards, '78). The amount of body water and its variations with time are known to depend upon the compartmentalization and mixing of water within the body, the kinetic order and rate constant of each process by which water molecules are supplied or removed, the physical factors of these processes, and physiological regulations of their rates (White, '68; Knulle and Devine, '72; Devine and Wharton, '73; Arlian and Wharton, '74; Arlian and Eckstrand, '75; Ellingsen, '75; Seethaler et al., '79). These characteristics differ so greatly among species and stages of arthropods that many additional studies are in order.The booklouse Liposcelis bostrychophilus is well suited as a subject in which to investigate components of the body water budget and their dynamics. Its biology has been described in considerable detail (Broadhead and Hobby, '44; Broadhead, '50; Speiksma and Smits, '75). It feeds continually, and it reproduces rapidly by thelytoky. The adults are of quite uniform size, if a bit small at 40 pg. They have a life-span of several months on food such as yeast, and in relative humidities as low as 60%. They survive both long periods of fasting and the loss of one-half of their normal amount of body water in temperatures from 7°C to 40°C. Of particular interest here, they can physiologically absorb...