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Cases of lymphohematopoietic cancer from three petroleum industry cohorts, matched to controls from the respective cohort, were pooled into single study. Average benzene exposure was quantitatively estimated in ppm for each job based on measured data from the relevant country, adjusted for the specific time period, site and job exposure characteristics and the certainty of the exposure estimate scored. The probability of dermal exposure and of peak exposure was also assessed. Before risk was examined, an exposure estimate comparison and rationalisation exercise was performed across the studies to ensure accuracy and consistency of approach. This article evaluates the final exposure estimates and their use in the risk assessments. Overall benzene exposure estimates were low: 90% of participants accumulated less than 20 ppm-years. Mean cumulative exposure was estimated as 5.15 ppm-years, mean duration was 22 years, and mean exposure intensity was 0.2 ppm. 46% of participants were allocated a peak exposure (>3 ppm at least weekly). 40% of participants had a high probability of dermal exposure (based on the relative probability of at least weekly exposure). There were differences in mean intensity of exposure, probability of peak, and/or dermal exposure associated with job category, job site, and decade of exposure. Terminal Operators handling benzene-containing products were the most highly exposed group, followed by Tanker Drivers carrying gasoline. Exposures were higher around 1940–1950 and lower in more recent decades. Overall confidence in the exposure estimates was highest for recently held jobs and for white-collar jobs. We used sensitivity analyses, which included and excluded case-sets on the basis of exposure certainty scores, to inform the risk assessment. The above analyses demonstrated that the different patterns of exposure across the three studies are largely attributable to differences in jobs, site types, and time frames rather than study. This provides reassurance that the previous rationalisation of exposures achieved inter-study consistency and that the data could be confidently pooled.

[EN] 1. The significance of airborne transmission in epidemics of infectious diseases in the livestock production industry remains unclear. The study therefore investigated the shedding route (faeces vs. exhaled air) of a vaccine strain of infectious bursal disease virus (IBDV) by broilers and the emission of airborne virus. 2. The experimental room contained 526 broilers which were orally inoculated at the age of 20 d. The airborne virus was sampled by three different bioaerosol samplers: Andersen six-stage impactor, all-glass impinger (AGI-30) and OMNI-3000. 3. Infected broilers started to shed virus in faeces on d 5 post inoculation (PI), and stopped shedding on d 12 PI. The faecal virus remained detectable for at least two d after drying under broiler room conditions. No virus was detected in the air exhaled by broilers. 4. Airborne virus was collected on d 5, 8 and 12 PI at 20 cm above the floor, and on d 8 and 12 PI in exhausted air. The emission rates of IBDV were 40 log10 50% tissue culture infectious dose (TCID50)/bird/d on d 8 PI, and 45 log10 TCID50/bird/d on d 12 PI. 5. We concluded that broilers shed IBDV mainly through their faeces. The presence of indoor airborne virus is associated with the viral presence in faeces. The successful recovery of airborne virus in exhausted air indicates there is a potential risk of virus spreading to the ambient environment via air., This work was supported by the AI-FES budget from the Dutch Ministry of Economic Affairs. We appreciate the dedicated work of Mr Xu Lu, Mr Machiel Esmann, Ms Thea Von Bannisseht, Ms Annelies Hoogkamer in this study. We thank Dr Joy Burrough for advice on the English.

(1) This research was carried out to investigate changes in egg production and hatchability as influenced by age and breeding season of 10 trios (two females, one male) of ostrich (Struthio camellus) during 1998 to 2002. (2) Breeding season affected number of eggs laid per female per season, average egg weight, length of laying period and clutch sequence. (3) The number of eggs laid per female per season was 25 in the first breeding season and 57 by the fifth breeding season. The laying period lasted 169 d in the first season whereas it was 210 d by the fifth season. The breeding season became longer year by year. (4) The number of clutches was two in the first season, three in the second and 4 in the later breeding seasons: the mean interval between cycles was 9 to 10.6 d and the mean number of eggs in one cycle varied from 12 to 14.4. (5) The breeding season affected the hatchability of fertile eggs, chick weight at hatching, hatchability of total eggs, fertility, malpositioned embryos, deformed chicks and assisted chicks during hatching. The first 4 variables increased and the last three decreased, with each breeding season. (6) Weight loss of eggs and length of incubation were unaffected by the breeding season. Hatchability which was 64.3% in the first season increased progressively and reached 73.1% in the fifth breeding season.