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K M Venables

Publications and source records attributed to K M Venables.

At least 37 records · Page 2Linked to original sources
PubMed1995

Exposure to acid anhydrides in three resin and one cushioned flooring manufacturing plants.

Acid anhydrides are reactive organic chemicals of low molecular weight which cause occupational asthma. No previous research on the relationship between exposure to these chemicals and respiratory sensitization and development of occupational asthma has been reported. A retrospective cohort study was carried out in four factories (three alkyd resin factories and one cushioned flooring factory) to investigate the nature of exposure-response relationships for sensitization to phthalic anhydride (PA), trimellitic anhydride (TMA) and maleic anhydride (MA). This paper describes the results of full-shift and task-specific exposure measurements. Exposure to PA was low in relation to the Occupational Exposure Standard (OES). The highest full-shift PA exposures occurred among resin operators in the resin factory that used solid PA as compared to other resin factories where liquid PA was used. Arithmetic mean exposure levels to TMA and MA in the resin factories were well below their respective OESs. Short-term high exposures occurred during loading of acid anhydrides into the reactors and sampling and testing of the resin. Relatively high full-shift exposure to TMA occurred in the cushioned flooring factory, although no high peak exposures were detected.

Anhydrides↗
PubMed1995

Variation in rat urinary aeroallergen levels explained by differences in site, task and exposure group.

We describe how much of the variation in rat urinary aeroallergen (RUA) levels may be explained by differences in site and exposure group in research establishments and we identify task categories associated with high RUA levels. In this population 73% of the variability in RUA levels could be explained by exposure group, site and their interaction term. Exposure group alone explained the majority of the variation (69%). The task category associated with the highest RUA level was cleaning out, followed by indirect contact with rats and handling rats. The task categories associated with the lowest levels were slide production, post mortem and experiments. These results may help choose appropriate exposure measures for epidemiological studies in research establishments in the future and may help reduce the incidence of laboratory animal allergy.

Allergens↗
PubMed1995

Peak exposure concentrations of dust and flour aeroallergen in flour mills and bakeries.

As part of an epidemiological study amongst workers exposed to flour we measured peak exposure levels to total dust and flour aeroallergen with personal samplers in bakeries, flour mills and packing stations. Short-term tasks which were expected to give rise to high concentrations of exposure (peaks) were identified. The frequency and duration of these tasks were estimated and their levels of exposure to dust and flour aeroallergen measured. In total 209 samples were taken. The highest exposure concentrations both for dust (geometric mean > 30 mg m-3) and for flour aeroallergen (geometric mean > 500 micrograms m-3) were measured during certain operations. Exposure concentrations for the tasks were often much higher than the levels we had measured over a shift in a previous study. This might be important for sensitization and for the development of asthma. Peak exposure concentrations could be used to explore the exposure-response relationship more comprehensively. In general average flour aeroallergen concentrations increased linearly with average dust concentrations, although there were some exceptions.

Allergens↗
PubMed1995

Correlation between different measures of exposure in a cohort of bakery workers and flour millers.

This paper describes the relationship between continuous and 'grouped' variables for several measures of exposure in a longitudinal study of bakery workers and flour millers. Average shift and peak levels, both for dust and for flour aeroallergen were measured, duration of exposure obtained from questionnaire and cumulative exposure both for dust and for flour aeroallergen calculated. Neither for dust nor for flour aeroallergen was there a correlation between duration of exposure and intensity measures of exposure (peak and average). Moderate to good correlation existed between the various intensity measures of exposures both for dust and for flour aeroallergen. Good correlations existed between measures of exposure of dust and measures of exposure for flour aeroallergen. The degree of correlation was reflected by the fact that the number of workers changing categories depended on which measure of exposure was considered. The higher the correlation coefficient between various measures of exposure the fewer workers changed category. This information provides important information for a better understanding of the exposure-response relationship amongst bakery workers and flour millers.

Allergens↗
PubMed1995

Flour dust exposure variability in flour mills and bakeries.

As part of a longitudinal study to explore the exposure-response relationship between flour dust exposure and work-related symptoms and skin sensitivity the authors formed exposure groups and estimated various components of variability. This paper describes the between-exposure group, the between-worker and the within-worker variation of personal flour dust exposure in bakeries, flour mills and packing stations. In total 346 samples were collected in 13 exposure groups. The geometric means of the exposure groups ranged from 0.3 up to 9.0 mg m-3. Between-worker variances within exposure groupings were less than the overall between-worker component although substantial differences in exposure between workers remained in some exposure groups. Overall the largest variance component was the between-exposure group component followed by the considerably smaller between-worker and within-worker components.

Analysis of Variance↗
PubMed1994

Respiratory symptoms, immunological responses, and aeroallergen concentrations at a sawmill.

After identification of a case of extrinsic allergic alveolitis due to exposure to wood dust at a sawmill, all employees at the sawmill where he worked were studied with an occupational, environmental, and symptom questionnaire, spirometry, skin prick tests, and serum specific IgG measurements. Ninety five of current and 14 of 17 ex-sawmill workers were studied. As a basis for comparison, a group of 58 workers from a nearby light engineering factory were also studied. Few women (6) were employed and they were excluded from the analysis. Workers at the sawmill were stratified into high and low exposure groups depending on their place of work. This division was supported both by their subjective assessment of the dustiness of their environment and the results of personal dust samples. There were no significant differences between the three groups in age, height, smoking habits, exposure to other causes of extrinsic allergic alveolitis, forced expiratory volume in one second, forced vital capacity, atopic state, or cutaneous reactivity to moulds. In the high exposure group the prevalence of work related cough and nasal and eye symptoms was higher than in the low exposure and comparison groups. The prevalence of work related wheeze was similar in both the high exposure and comparison groups, but was lower in the low exposure group. The prevalences of chronic bronchitis and symptomatic bronchial hyper-reactivity were similar in the high and low exposure groups but were lower in the comparison group. Serum concentrations of specific IgG against extracts of sawdust and Trichoderma koningii were significantly higher in the high exposure group than in the other two groups. The prevalence of symptoms suggestive of extrinsic allergic alveolitis was 4.4% in the high exposure group, greater than in the low exposure group (0%), and the comparison group (1.9%). In conclusion extrinsic allergic alveolitis probably occurs in British sawmills, and among the exposed population its prevalence may be as high as that reported in Sweden. The allergen responsible is likely to be from mould growing on the wood and may be from Trichoderma koningii.

Adolescent↗
PubMed1994

Work related symptoms, sensitisation, and estimated exposure in workers not previously exposed to flour.

Findings are presented from the initial cross sectional phase of a cohort study of employees exposed to flour in bakeries or mills. Of 401 eligible workers in seven sites 344 (86%) were surveyed; symptoms assessed by self completed questionnaire, and sensitisation measured by the response to skin prick tests, were related to intensity of exposure both to total dust and to flour aeroallergen. Among 264 subjects without previous occupational exposure to flour, work related symptoms which started after first employment at the site were related to exposure intensity, especially when exposure was expressed in terms of flour aeroallergen. The relations with eye/nose and skin symptoms were independent of atopic status and cigarette smoking. Positive skin test responses to mixed flour and to alpha amylase were also more frequent with increasing exposure intensity, although this was confounded by atopic status. There was only a weak association between symptoms and specific sensitisation.

Adult↗
PubMed1994

Dust and flour aeroallergen exposure in flour mills and bakeries.

As part of an epidemiological study among workers exposed to flour total dust and flour aeroallergen concentrations were measured with personal samplers over a workshift in three large bakeries and four flour mills and packing stations. In the bakeries geometric means for total dust concentrations ranged from 0.4 mg/m3 in the bread wrapping area up to 6.4 mg/m3 at the dough brake. The flour aeroallergen concentrations ranged from 45.5 micrograms/m3 in the bread wrapping area up to 252.0 micrograms/m3 in the confectionary area. In the flour mills and packing stations the concentrations were higher with geometric means for total dust ranging from 0.5 mg/m3 in the office up to 16.9 mg/m3 for hygiene workers in an old mill. The flour aeroallergen concentrations ranged from 101.5 micrograms/m3 for transport workers up to 1728.2 micrograms/m3 for hygiene workers. The relation between total dust and flour aeroallergen concentrations varied for different areas and depended on the use of products other than flour.

Allergens↗
PubMed1994

Work related symptoms, sensitisation, and estimated exposure in workers not previously exposed to laboratory rats.

Findings are presented from the initial cross sectional phase of a cohort study of employees exposed to laboratory rats. Of 366 eligible workers at four sites 323 (88%) were surveyed; symptoms assessed by self completed questionnaire and sensitisation measured by the response to skin prick tests were related to intensity of exposure both to total dust and to rat urinary aeroallergen. Among 238 workers, without previous occupational exposure to rats, work related symptoms, which started after first employment at the site were related to exposure intensity (expressed either in terms of dust or of aeroallergen) at the time of onset of symptoms. These relations were stronger in atopic subjects but were unrelated to smoking. Positive skin tests to rat urinary extract were also more frequent with increased exposure, a relation found in both atopic subjects and in smokers. There was a strong association between work related symptoms and specific sensitisation.

Adult↗
PubMed1994

Exposure to dust and rat urinary aeroallergens in research establishments.

As part of an epidemiological study rat urinary aeroallergen (RUA) and total dust concentrations were measured at three research establishments. Personal RUA measurements in nine exposure groups over a workshift showed highest exposure for animal technicians (geometric mean (GM) = 32.4 micrograms/m3) and lowest for workers in slide production and office (GM > or = 0.1 micrograms/m3). Except for slide production workers, contact with rats, their tissues, faeces, or urine comprised less than half the work shift. Exposure during contact with rats was considerably higher. Personal RUA measurements in nine task categories showed high RUA concentrations for handling rats (GM = 68.0 micrograms/m3) and cleaning out (GM = 53.6 micrograms/m3). Traces of RUA could still be measured in tearooms inside and near offices outside the animal houses. Total dust concentrations were low.

Allergens↗
PubMed1994

Prevention of occupational asthma.

This paper focuses on the prevention of asthma caused by exposure to sensitizing agents in the workplace. Control of exposure (primary prevention) is the most direct method of reducing the number of incident cases. Screening programmes are also necessary as a "safety net", and have value as secondary prevention, because early detection may improve long-term prognosis. It is recommended that regulatory or advisory bodies with responsibility for occupational asthma publish a guidance document on occupational asthma explaining their current concepts. Surveillance activities provide information on how common asthma is relative to other occupational lung diseases, and on the relative frequency of occurrence of asthma caused by different agents. Publication of a list of sensitizing agents would aid those with responsibility for control of exposure in the workplace. Epidemiological research on exposure-response relations is is necessary as a background to prevention. This paper recommends such studies. Immunotoxicological research also has a role in testing hypotheses that cannot be tested in human subjects. Some standardization of screening programmes in industry is desirable. A short symptoms questionnaire is economical and acceptable to workers, but there are other approaches. Finally, evaluative research on prevention measures gives information on their effectiveness and efficiency.

Allergens↗
PubMed1993

Respiratory symptoms questionnaire for asthma epidemiology: validity and reproducibility.

BACKGROUND: There is a need for a new respiratory symptoms questionnaire for use in epidemiological research in asthma. METHOD: A questionnaire was designed following a pilot study in 78 subjects. It contains nine questions on symptoms such as wheeze and difficulty with breathing in defined circumstances such as exercise and sleep. It was completed by 211 adults and validated by comparison with a self reported history of asthma and with bronchial hyperresponsiveness to histamine. Its short term reproducibility was measured by three repeat administrations over two weeks. RESULTS: Subjects with asthma (n = 33), particularly those having had an asthma attack in the last year (n = 23), were more likely to report any symptom and to report a greater number of symptoms than those without asthma. The same relationship was found for bronchial hyperresponsiveness and symptoms. Either two or more, or three or more, symptoms appeared to be good indices of self reported asthma and bronchial hyperresponsiveness, or both, with a high sensitivity (65-91%) and specificity (85-96%). Reproducibility was good, with few subjects changing the number of symptoms reported by more than one symptom and none by more than four symptoms. The results compared favourably with those from questions on phlegm production from the MRC questionnaire and were better than those reported for the MRC wheeze questions. CONCLUSIONS: The questionnaire will be useful for epidemiological research on asthma and could form part of a new standardised questionnaire with wide applications.

Adult↗
PubMed1993

Bronchial responsiveness and the reproducibility of forced expiratory volume in one second.

Although poorly reproducible spirometric tests, "test failures," are associated with respiratory morbidity, it is not clear what causes them. Bronchial responsiveness was examined in relation to test failure for forced expiratory volume in 1 s (FEV1.0) (1979 definition of the American Thoracic Society) in 249 bakers, 165 chemical industry workers, and 204 office workers. The first two groups were studied by the same methods and were combined. Test failure was observed in 4%, and for 38% the provocative dose of inhaled methacholine causing a 20% fall in FEV1.0 relative to FEV1.0 after the inhalation of normal saline (PD20) was < or = 120 mumol (7% with a PD20 of < or = 8 mumol). Test failure was not related to the level of PD20. Of the office workers, 3% had test failure, 11% a PD20 of < or = 8 mumol of histamine, and no significant relation was observed. The study does not exclude the possibility that bronchial responsiveness might be related to test failure in patients with airway disease or that a clearer relation might be demonstrable in a larger study, but it does suggest that it is not a major determinant of test failure.

Adult↗
PubMed1992

Immune response to flour and dust mites in a United Kingdom bakery.

In a study of 279 United Kingdom bakery workers a high prevalence of immunological response to storage mites was found. To determine whether this was the consequence of exposure to storage mites in bakery work, a population of salt packing workers was examined as a comparison group not at occupational risk of exposure to storage mites. Forty two per cent of both groups were atopic (had a positive skin prick response greater than negative controls to D pteronyssinus, grass pollen, or cat fur by 2 mm or more) and 33% had an immediate skin prick test response to at least one of four storage mites (L destructor, G domesticus, T putrescentiae, A Siro). A higher percentage of the salt packing workers than the bakery workers had a positive radioallergosorbent test (RAST) (greater than or equal to 0.35 PRU) to D pteronyssinus and to the four storage mites. Logistic regression analysis identified atopy as the most significant variable for a positive skin test and RAST response to storage mites in both groups of workers. RAST inhibition was used to analyse extracted area and personal air samples. Analysis of static area samples for aeroallergen showed immunological identity with flour but L destructor was found in only one of seven exposed filters. The concentration of airborne flour was related to exposure rank of perceived dustiness and gravimetric measurement of total dust. Nineteen out of 32 filters from workers in jobs with higher dust exposure (rank >/=6) had a level of > 10 microgram/m(3) flour whereas this concentrations was exceeded in only one of 23 filters from workers in low dust exposure (< rank 6). It is concluded that storage mites are not of special significance in allergic responses in bakery workers. The development of immunological (and airway) responsiveness to inhaled flour dust is increased in those exposed to higher concentrations of airborne allergen, which appears to be predominantly flour and not storage mites.

Air Pollutants, Occupational↗
PubMed1990

Exposure-response relationships in asthma caused by tetrachlorophthalic anhydride.

Four patients with asthma caused by occupational exposure to tetrachlorophthalic anhydride (TCPA) had dust-challenge tests that used eight different levels of TCPA exposure. Measurements of TCPA in the test-cubicle air ranged from 1.3 to 961.1 micrograms/m3. The higher exposures provoked definite late or dual asthmatic responses. Smaller, but statistically significant, responses were observed at low exposures. The late asthmatic-response area had a linear relation to the logarithm of TCPA exposure, but the immediate asthmatic response was less closely related to exposure.

Adult↗