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K M Venables

Publications and source records attributed to K M Venables.

At least 19 recordsLinked to original sources
PubMed2006

Occupational health needs of universities: a review with an emphasis on the United Kingdom.

This study describes the needs of universities in relation to planning the provision of occupational health services, by detailing their occupational hazards and risks and other relevant factors. The paper presents the results of (1) an enquiry into publicly available data relevant to occupational health in the university sector in the United Kingdom, (2) a literature review on occupational health provision in universities, and (3) selected results from a survey of university occupational health services in the UK. Although the enquiry and survey, but not the literature review, were restricted to the UK, the authors consider that the results are relevant to other countries because of the broad similarities of the university sector between countries. These three approaches showed that the university sector is large, with a notably wide range of occupational hazards, and other significant factors which must be considered in planning occupational health provision for individual universities or for the sector as a whole.

Health Status↗
PubMed2004

Association of HLA-DQ5 and HLA-DR1 with sensitization to organic acid anhydrides.

BACKGROUND: Organic acid anhydrides are low molecular weight industrial chemicals, able to cause rhinoconjunctivitis and asthma associated with specific IgE against hapten-carrier protein conjugate. Only a proportion of exposed workers develop IgE-associated allergy to acid anhydrides. OBJECTIVE: We determined whether genetic susceptibility, in particular, HLA Class II alleles may be a risk factor. METHODS: We undertook HLA typing in 52 cases who had confirmed specific IgE and in 73 referents matched on site, age and duration of acid anhydride exposure identified in cross-sectional studies of workers exposed to hexahydrophthalic (HHPA), methylhexahydrophthalic (MHHPA) and methyltetrahydrophthalic (MTHPA) anhydrides. RESULTS: The linked alleles DQ5 (odds ratio [OR]=4.3; 95% confidence interval [95% CI]=1.7, 11) and DR1 (OR 3.0; 95% CI 1.2, 11) were more prevalent in cases than in referents. Within DQ5, DQB1(*)0501 was particularly frequent (OR 3.0; 95% CI 1.2, 7.4). CONCLUSION: DQB1(*)05 gene confers susceptibility to develop specific IgE antibodies against HHPA, MHHPA and a non-significant trend with MTHPA. DQB1(*)0501 is protective for other low molecular chemical sensitizers (isocyanates and plicatic acid) which may indicate varying affinities for the corresponding specific class II molecules.

Adult↗
PubMed2004

Exposure-response relations for work related respiratory symptoms and sensitisation in a cohort exposed to alpha-amylase.

AIMS: To explore relations between exposure to fungal alpha-amylase and the risk of new work related respiratory symptoms or sensitisation. METHODS: A prospective cohort study among 300 bakers and millers was followed up for a maximum of seven years. Exposure to alpha-amylase was estimated by air measurements and questionnaires and classified into three categories. Symptoms were recorded with a self-administered questionnaire and skin sensitisation assessed using skin prick test (SPT). RESULTS: There were 36 new cases of chest symptoms, 86 of eyes/nose symptoms, and 24 of a positive SPT to alpha-amylase. There were exposure-response relations for chest and eyes/nose symptoms and for sensitisation, and a significantly increased prevalence ratio for chest symptoms in the highest exposure category. CONCLUSION: A reduction in alpha-amylase exposure is likely to reduce the risk for respiratory morbidity in bakery workers.

Cohort Studies↗
PubMed2003

Exposure-response relations among laboratory animal workers exposed to rats.

AIM: To explore exposure-response relations in a cohort of laboratory animal workers. METHODS: Exposure-response modelling was carried out in a cohort of 342 laboratory animal workers. Three exposure indices, divided into different exposure categories, were used in the analyses: intensity of exposure to rat urinary aeroallergen (RUA, the main allergen workers were exposed to), weekly duration of exposure to rats, and the product of the intensity and weekly duration of exposure. Outcomes studied were work related chest, eyes and nose, and skin symptoms that had started after employment at the sites, specific sensitisation, and a combination of symptoms and sensitisation. Cox proportional hazard modelling was used to explore exposure-response relations. Smoking, atopic status, age, and gender were taken into account. RESULTS: We observed the clearest exposure-response relations for the intensity of exposure to RUA and the various endpoints. No clear exposure-response relations were observed for the weekly duration of exposure or the product of the intensity and weekly duration of exposure. The strongest and clearest exposure-response relations for symptoms were observed among rat sensitised workers, while the non-sensitised workers only showed small increased risks of developing symptoms without clear exposure-response relations. Sensitised workers were almost four times more likely to go on to develop chest symptoms compared to non-sensitised workers.

Adult↗
PubMed2001

Allergen and dust exposure as determinants of work-related symptoms and sensitization in a cohort of flour-exposed workers; a case-control analysis.

OBJECTIVES: To estimate the incidence of specific IgE sensitization and allergic respiratory symptoms among UK bakery and flour mill workers; and to examine the roles of flour aeroallergen and total dust exposures in determining these outcomes. METHODS: A cohort of 300 new employees, without previous occupational exposure to flour, were followed prospectively for a median (range) of 40 (1-91) months. Cases-defined as those developing work-related symptoms or a positive skin prick test to flour or alpha-amylase during follow up--were compared with controls, matched for duration of employment. Exposures to flour aeroallergen and total inhalable dust were estimated using a questionnaire and personal sampling techniques. RESULTS: Incidence rates for work-related eye/nose and chest symptoms were 11.8 and 4.1 cases per 100 person years (py), respectively. Fewer employees developed positive skin prick tests to flour (2.2 cases per 100 py) or alpha-amylase (2.5 cases per 100 py). Positive skin tests to occupational allergens were more common among those with new work-related symptoms. There were clear relationships between the risks of developing work-related symptoms or a positive skin prick test and three categories of estimated exposure to total dust or flour aeroallergen. Atopic employees were more likely to develop a positive skin prick test-but not work-related symptoms. These findings were unaffected by age, sex or cigarette smoking. CONCLUSIONS: In this population, many work-related symptoms which develop after first employment in modern UK bakeries or flour mills were not accompanied by evidence of IgE sensitization to flour or alpha-amylase. Although average dust exposures were within current occupational standards, the risks of development of upper and lower respiratory symptoms and of specific sensitization were clearly related to total dust and/or flour aeroallergen exposure. The incidence of work-related chest symptoms in the presence of a positive skin test to flour or alpha-amylase in this setting was approximately 1 case per 100 py.

Adult↗
PubMed2000

Risk factors for bronchial hyperresponsiveness in workers exposed to acid anhydrides.

Risk factors for bronchial hyperresponsiveness have previously been established in the general community. In settings where occupational asthma is a risk, it has not been established whether occupational sensitization or measures of exposure are important. Bronchial responsiveness to histamine was measured in a cohort of 506 workers exposed to acid anhydrides. Skin-prick tests were performed with conjugates of phthalic, maleic and trimellitic anhydride with human serum albumin and with common inhalant allergens. Employment and smoking histories were recorded. Occupational exposure was measured using personal air samplers and estimates of past exposure made by retrospective exposure assessment. Three hundred and seventy workers (73%) had bronchial responsiveness measured (median age 39 yrs, range 18-77) and 46 (12%) of these were hyperresponsive (provocative dose causing a 20% fall in forced expiratory volume in one second (FEV1; PD20) < or = 8 micromol). Twelve (3%) of these responsive workers had a skin-prick test reaction to an acid anhydride conjugate, 124 (34%) to a common inhalant allergen, and 148 (40%) were current smokers. Multivariate analysis showed that occupational sensitization, sensitization to a common inhalant allergen, age, and pack-years of smoking were independent risk factors for bronchial hyperresponsiveness. Of these only occupational sensitization was completely independent of baseline FEV1. It is concluded that sensitization to acid anhydrides is a significant risk factor for bronchial hyperresponsiveness. However, measures of personal acid anhydride exposure were not associated with bronchial hyperresponsiveness.

Adolescent↗
PubMed1999

Exposure-response relationships for work-related sensitization in workers exposed to rat urinary allergens: results from a pooled study.

BACKGROUND: Recent studies in a few industries have shown that the likelihood of IgE-mediated sensitization increases with increasing exposure. The shape of the exposure-response relationships and modification by age, sex, and smoking habit has hardly been studied. OBJECTIVE: The purpose of this study was to determine exposure sensitization relationships for rat sensitization and to evaluate the influence of atopy, smoking habits, and sex. METHODS: Data from 3 cross-sectional studies in The Netherlands, the United Kingdom, and Sweden were used and involved 1062 animal laboratory workers. Selection criteria were harmonized, and this resulted in a study population of 650 animal laboratory workers (60.6% female) with less than 4 years of exposure. Air allergen levels were assessed previously and converted on the basis of an interlaboratory allergen analysis comparison. Available sera were analyzed for the presence of specific antibodies against common allergens (house dust mite, cat, dog, and grass and birch pollen) and work-related allergens (rat and mouse urinary proteins). Questionnaire items on work-related respiratory symptoms, hours worked with rats per week, job performed, smoking habits, and sex were used in this analysis RESULTS: The prevalence of work-related sensitization to rat urinary allergens (IgE >0.7 KU/L) was 9.7 % (n = 63). Thirty-six of the sensitized workers had work-related symptoms (asthma or rhinitis). Two hundred forty-eight workers (38.2%) were atopic (defined as specific IgE to 1 of the common allergens). The sensitization rate increased with increasing air allergen exposure. Atopic workers exposed to low levels of allergen had a more than 3-fold increased sensitization risk compared with nonexposed atopic workers. For atopic subjects, the risk increased little with increasing exposure, whereas for nonatopic subjects, a steadily increasing risk was observed. Smoking and sex did not modify the sensitization risk. CONCLUSION: Rat urinary allergen-sensitization risk increased with increasing exposure intensity. Workers who were atopic had a clearly elevated sensitization risk at low allergen exposure levels.

Allergens↗
PubMed1999

Comparison of methods to assess airborne rat and mouse allergen levels. I. Analysis of air samples.

Airborne laboratory-animal allergens can be measured by several methods, but little is known about the effects of important differences in methodology. Therefore, methods used in research projects in The Netherlands, the UK, and Sweden were compared. Seventy-four sets of three parallel inhalable dust samples were taken by a single operator in animal facilities in the three countries, and analyzed in parallel by the three institutes for rat and mouse urinary allergen. Rat-allergen levels measured by RAST inhibition (UK) were 3000 and 1700 times higher than levels measured by enzyme immunoassay (EIA)-sandwich methods with polyclonal rabbit (The Netherlands) or monoclonal mouse (Sweden) antibodies, while the difference between the two EIA-sandwich methods was much smaller: a factor of 2.2. For mouse allergen, an inhibition radioimmunoassay (RIA) with rabbit antimouse antibodies (UK) gave 4.6 and 5.9 times higher concentrations than sandwich EIAs with rabbit polyclonal antibodies (Sweden and The Netherlands), while the difference between the two sandwich EIAs was, on average, 1.6-fold. Thus, although levels of rat and mouse aeroallergens are significantly correlated, the assay type gives large differences in absolute concentrations, and interlaboratory technical differences affect even the same assay type. Conversion factors can aid comparison between studies, and, in the long term, assay standardization is desirable.

Air Pollutants↗
PubMed1999

Comparison of methods to assess airborne rat and mouse allergen levels. II. Factors influencing antigen detection.

Potential factors influencing antigen detection in immunoassays for measuring rat or mouse aeroallergen (i.e., assay setup, antigen specificities, standard extracts used, and antigen decay) were investigated in a three-country study (the UK, The Netherlands, Sweden). An inhibition enzyme immunoassay (EIA) setup gave nominal rat urinary allergen (RUA) sample values seven times higher than a sandwich EIA setup utilizing identical antibodies and standards. In immunoblotting experiments, pooled patient serum and polyclonal rabbit antibodies partly detected different rat antigens; monoclonal antibody specificity could not be determined. Immunoblot detection of mouse urinary antigens (MUA) by the polyclonal rabbit antibodies from all laboratories was similar. In both the RUA and the MUA assays, urinary antigen standards were detected with similar potency, except purified Rat n 1, which was an inefficient inhibitor in the RUA RAST inhibition. In the sandwich EIA RUA assays, a rat room-dust extract was detected with 700800-fold less sensitivity than rat urine, whereas in the RAST RUA assay, dust inhibited equally with rat urine. Simulated decay did not decrease the potency of urinary antigen in any assay. Thus, assay setup and choice of detection antibodies strongly influence the nominal allergen levels. We recommend the use of standardized and characterized antibodies and standard extracts in sandwich EIAs to measure airborne rodent urinary allergens.

Air Pollutants↗
PubMed1999

Allergen exposure, atopy and smoking as determinants of allergy to rats in a cohort of laboratory employees.

This study aimed to examine the relationship between exposure to rat urinary allergens, atopic status, smoking and the development of allergic symptoms and specific sensitization. It is a case-referent analysis of a cohort of 342 newly employed laboratory animal workers. Cases comprised persons developing symptoms of laboratory animal allergy or a positive skin prick test to rat urinary allergens; each was matched with up to two asymptomatic referents. Subjects were assigned to categories of exposure based on measurements of airborne rat urinary allergens. Of the cases, 80% reported that their symptoms started within 2 yrs of employment. The odds ratio (OR) for development of each symptom type (respiratory, eye or nose and skin) and of an immediate skin test reaction was increased in those with direct contact with rats. A gradient of increasing OR for the development of any such symptom across exposure categories was found; for respiratory symptoms and skin test reactions the OR for subjects in the highest exposure category were lower than those in intermediate categories, a pattern attenuated when the analysis was confined to outcomes developing within 2 yrs of first exposure. Atopy increased the OR of most outcomes as did cigarette smoking, although there was no evidence of a relationship between smoking and the development of a specific skin test reaction. In conclusion, allergen exposure was confirmed as the most important determinant of laboratory animal allergy; by implication, measures to reduce exposure may be the most effective means to reduce its incidence.

Adult↗
PubMed1999

Exposure-response relations of alpha-amylase sensitisation in British bakeries and flour mills.

OBJECTIVES: To describe the levels of exposure to fungal alpha-amylase in British bakeries and flour mills, and to describe the relation between exposure to alpha-amylase and sensitisation to fungal alpha-amylase. METHODS: 495 personal flour dust samples were taken in seven British bakeries and flour mills and analysed for alpha-amylase with an immunoassay. Workers at the sites were asked to fill out questionnaires on work related symptoms, smoking history, and work history, and they were skin prick tested with common allergens and fungal alpha-amylase to assess sensitisation. RESULTS: Exposure to high concentrations of alpha-amylase occur in a few areas of British bakeries and flour mills, and there can be considerable differences in exposures to alpha-amylase between sites and between exposure groups, and even within similar exposure groups from different sites. Exposure to the highest concentrations of alpha-amylase was found in the dispensing and mixing areas of the bakeries (geometric mean (GM) 39.7 ng/m3). Exposure to alpha-amylase showed only a moderate correlation with concentrations of dust (r = 0.42) and flour aeroallergen (r = 0.46). The results also showed a relation between exposure to alpha-amylase and sensitisation to fungal alpha-amylase (prevalence ratio (PR) for medium exposure 3.9, 95% confidence interval (95% CI) 0.8 to 20.2, PR for high exposure 9.9, 95% CI 2.8 to 34.6) compared with the low exposure category). Atopic subjects had an increased risk of sensitisation, but this was not significant. CONCLUSION: This study suggests that exposure to alpha-amylase is a considerable health risk in British bakeries and flour mills. A small proportion of workers are exposed to alpha-amylase at concentrations that result in high rates of sensitisation. A reduction in exposure to alpha-amylase is likely to reduce this risk.

Adult↗
PubMed1998

Risk factors for sensitisation and respiratory symptoms among workers exposed to acid anhydrides: a cohort study.

OBJECTIVES: To examine the relation between exposure to acid anhydrides and the risk of developing immediate skin prick test responses to acid anhydride human serum albumin (AA-HSA) conjugates or work related respiratory symptoms; to assess whether these relations are modified by atopy or smoking. METHODS: A cohort of 506 workers exposed to phthalic (PA), maleic (MA), and trimellitic anhydride (TMA) was defined. Workers completed questionnaires relating to employment history, respiratory symptoms, and smoking habits. Skin prick tests were done with AA-HSA conjugates and common inhalant allergens. Exposure to acid anhydrides was measured at the time of the survey and a retrospective exposure assessment was done. RESULTS: Information was obtained from 401 (79%) workers. Thirty four (8.8%) had new work related respiratory symptoms that occurred for the first time while working with acid anhydrides and 12 (3.2%) were sensitised, with an immediate skin prick test reaction to AA-HSA conjugates. Sensitisation to acid anhydrides was associated with work related respiratory symptoms and with smoking at the time of exposure to acid anhydride. When all subjects were included and all three acid anhydrides were taken into account there was no consistent evidence for an exposure-response relation, but with the analysis restricted to a factory where only TMA was in use there was an increased prevalence of sensitisation to acid anhydrides and work related respiratory symptoms with increasing full shift exposure. This relation was apparent within the current occupational exposure standard of 40 micrograms.m-3 and was not modified significantly by smoking or atopy. CONCLUSIONS: Intensity of exposure and cigarette smoking may be risk factors for sensitisation to acid anhydrides. Exposure is also a risk factor for respiratory symptoms. As there was evidence for sensitisation to TMA at full shift exposures within the occupational exposure standard this standard should be reviewed.

Adolescent↗
PubMed1998

Retrospective exposure assessment for a cohort study into respiratory effects of acid anhydrides.

OBJECTIVES: To estimate past exposure to phthalic (PA), trimellitic (TMA) and maleic anhydride (MA) in three alkyd resin and one cushioned flooring factory to estimate exposure-response relations in a retrospective cohort study. METHODS: Personal exposure measurements were carried out in 1992 and quantitative and qualitative information on past exposure and production processes were collected. Job titles were ranked by decreasing exposure and amalgamated into job categories and exposure groups. Multiplication factors for back calculating past exposure levels were estimated with past exposure data, or if no such data were available these factors were estimated by a panel of occupational hygienists. Exposure levels were back calculated starting with the exposure levels in 1992. RESULTS: High exposures to PA were estimated to have occurred among workers operating the PA melting pots in factory 1 (estimated exposure in 1960-9 was 2480 micrograms.m-3). Highest concentrations of TMA were estimated to have occurred among the ink mixers in factory 2 from 1979 to 1986 (554 micrograms.m-3). Exposure in most other job titles was thought to be fairly constant over time for PA, TMA, and MA. CONCLUSIONS: Exposure to acid anhydride at these factories has fallen during the period covered by the study. However, it is estimated that in only one job in factory 2 did past exposure to acid anhydride exceed the current occupational exposure standard. Accuracy of the estimated exposure is limited by a paucity of reliable past exposure data.

Anhydrides↗
PubMed1998

Stepwise health surveillance for bronchial irritability syndrome in workers at risk of occupational respiratory disease.

OBJECTIVES: Questionnaires, lung function tests, and peak flow measurements are widely used in occupational health care to screen for subjects with respiratory disease. However, the diagnostic performance of these tests is often poor. Application of these tests in a stepwise manner would presumably result in a better characterisation of subjects with respiratory disease. METHODS: Cross sectional data from workers exposed to acid anhydrides, to laboratory animals, and to flour dusts were used. Sensitivity and specificity were calculated from cross tables of different (combinations of) tests for bronchial hyperresponsiveness and bronchial irritability in the past four weeks (BIS). From sensitivity and specificity likelihood ratios were computed and change in probability of BIS was calculated. RESULTS: The prevalence of BIS was 7%, 7%, and 5%, respectively. In all groups questionnaire data provided excellent sensitivity but poor specificity, which was inherent on the broad definition of symptoms. Adding the forced expiratory volume in one second/forced vital capacity (FEV1/FVC) ratio yields almost perfect specificity, and peak expiratory flow (PEF) variability is intermediate in populations in which smoking induced or non-allergic respiratory diseases predominates. In occupational groups in which asthma is a problem, adding PEF measurements will optimise sensitivity and specificity in detection of BIS. The probability of BIS for subjects with a negative combined test outcome was lower than the probability before testing. Subjects with a positive combined test outcome had a probability of BIS after the tests at least three times the probability before. CONCLUSIONS: Combined testing yields better sensitivity and specificity. An advantage of combined testing is an economy in the effort to screen for subjects with BIS. Combined testing resulted in more detailed estimation of the probability of BIS.

Anhydrides↗
PubMed1997

Occupational asthma.

Occupational asthma is a common disorder that may be caused by several hundred agents and has a variety of pathogenetic mechanisms. Level of exposure is an important risk factor, and reduction of exposure is the only certain method of prevention. Atopy and smoking are further risk factors for IgE-mediated asthma but have not been found to increase risk in forms of the disorder that have other mechanisms. The key to diagnosis is a low threshold of suspicion; several investigative procedures can be used to confirm the diagnosis. Many patients suffer from continued asthma despite cessation of exposure; early diagnosis and early removal from exposure are the most important factors for improving the long-term outcome.

Asthma↗
PubMed1997

Thunderstorm-related asthma--the epidemic of 24/25 June 1994.

BACKGROUND: A large epidemic of asthma occurred following a thunderstorm in southern and central England on 24/25 June 1994. A collaborative study group was formed. OBJECTIVES: To describe the epidemic and the meteorological, aerobiological and other environmental characteristics associated with it. METHODS: Collation of data from the Meteorological Office, the Pollen Research Unit, the Department of the Environment's Automatic Urban Network, from health surveillance by the Department of Health and the National Poisons Unit, from clinical experience in general practice and hospitals, and from an immunological study of some of the affected cases from north east London. RESULTS: The thunderstorm was a Mesoscale Convective System, an unusual and large form of storm with several centres and severe wind gusts. It occurred shortly after the peak grass pollen concentration in the London area. A sudden and extensive epidemic occurred within about an hour affecting possibly several thousand patients. Emergency services were stretched but the epidemic did not last long. Cases had high serum levels of IgE antibody to mixed grass pollen. CONCLUSION: This study supports the view that patients with specific IgE to grass pollen are at risk of thunderstorm-related asthma. The details of the causal pathway from storm to asthma attack are not clear. Case-control and time series studies are being carried out.

Adult↗
PubMed1996

A major outbreak of asthma associated with a thunderstorm: experience of accident and emergency departments and patients' characteristics. Thames Regions Accident and Emergency Trainees Association.

OBJECTIVE: To investigate the time course of an epidemic of asthma after a thunderstorm, characteristics of patients affected, and the demand on emergency medical resources. DESIGN: Study of registers and records in accident and emergency departments and questionnaire to staff. SETTING: London area. SUBJECTS: All patients presenting at 12 accident and emergency departments with asthma or other airway disease. MAIN OUTCOME MEASURES: Numbers of patients, clinical features, information on shortage of resources--equipment, drugs and staff. RESULTS: The epidemic had a sudden onset on 24 June 1994; 640 patients with asthma or other airways disease attended during 30 hours from 1800 on 24 June, nearly 10 times the expected number. Over half (365) the patients were aged 21 to 40 years. A history of hay fever was recorded in 403 patients; for 283 patients this was the first known attack of asthma; a history of chronic obstructive airways disease was recorded in 12 patients. In all, 104 patients were admitted (including five to an intensive care unit). Several departments ran out of equipment or drugs, called in additional doctors, or both. CONCLUSIONS: This study supports the view that this epidemic was larger than previously reported epidemics and the hypothesis that "thunderstorm associated asthma' is related to aeroallergens. Demands on resources were considerable; a larger proportion of patients needing intensive care would have caused greater problems.

Adult↗