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PubMed1997

An evaluation of the respiratory health status of automotive spray-painters exposed to paints containing hexamethylene di-isocyanates in the greater Durban area.

OBJECTIVE: A survey of automotive spray-painting establishments was undertaken to evaluate the respiratory health status of spray-painters exposed to paints containing hexamethylene di-isocyanates (HDIs). DESIGN: This was a cross-sectional study. SETTING: Spray-painting establishments in the Durban municipal area. PARTICIPANTS: Spray-painters from a random sample of 40 (25%) of the registered spray-painting establishments were studied. MAIN OUTCOME MEASURES: Responses to an Interviewer-administered standardised respiratory health questionnaire and a cross-shift spirometric lung function test were obtained for each spray-painter, questionnaires assessing the firm's compliance with the spray-painting safety requirements were also obtained. RESULTS: The mean cross-shift decrease in forced expiratory volume in 1 second (FEV1) was 130.5 ml (SD 203.19) (P = 0.0002). The lung function data indicated that of the 40 spray-painters examined, 10 (25%) showed clinically significant cross-shift decreases in FEV1, viz, decreases > 250 ml. Only 2 subjects had a diagnosis of asthma. Chronic respiratory symptoms of cough, wheeze and wheeze with breathlessness were similar to those noted in community-based studies. A high proportion had eye irritation (55%) and dermatitis of the hand (32%). The potential determinants of FEV1 were examined in a multiple linear regression analysis and only the isocyanate concentration levels approached statistical significance (P = 0.082), suggesting that other factors such as duration of exposure, spray-paint 'bounce-back' phenomenon, and 'healthy worker' effect may be more important. ('Bounce back' refers to the phenomenon whereby some of the mist from the spray-gun, after striking the surface being painted, is deflected back into the operator's breathing zone in the form of fine droplets or aerosols.) Forty per cent of the 40 spray booths had ventilation standards substantially below that specified in current South African legislation. Only 21 (55%) spray-painters were provided with the regulation respiratory protective equipment, and in the cases where it was provided, 7 (33%) of these spray-painters used the positive pressure air-line respiratory recommended by the leading manufacturers of isocyanate-based paints. CONCLUSIONS: The findings in this study confirm the risk of exposure to HDIs in the spray-painting industry and highlight the need for more stringent industrial hygiene controls.

Adult↗
PubMed1999

Cotton dust and endotoxin exposure and long-term decline in lung function: results of a longitudinal study.

BACKGROUND: To evaluate the relationship between long-term exposure to cotton dust and Gram-negative bacterial endotoxin on lung function, we conducted an 11-year follow-up study of cotton textile workers in Shanghai, China. METHODS: Workers at a nearby silk-thread manufacturing mill were used as a referent population. Ninety percent of the original cohort of 445 cotton and 467 silk textile workers--both active and retired--were identified for testing in the 11th year. Questionnaires and spirometric testing were performed, as well as cotton dust and endotoxin sampling at three points over the 11-year follow-up period: at baseline, at Year 5, and at Year 11. After excluding deaths and subjects on sick-leave, 84% of the original cohort had complete health and environmental data. RESULTS: The data were reanalyzed using generalized estimating equations feedback model which allow for subject transfer over time between work areas, various exposure levels to dust and endotoxin, and FEV1. Cotton workers had a larger loss of FEV1 during the first 5 years of study (-40 mls/yr) as compared with the second 6 years of follow-up (-18 mls/yr). During the same periods, the average decline among silk workers was slightly higher in the first period, but was more consistent (-30 mls/yr vs. -27 mls/yr), and these differences could not be explained by worker selection or dropout. When cumulative exposure to dust and endotoxin were estimated and used in a multivariate model (GEE) for FEV1 loss, cumulative dust, but not endotoxin, was associated with 11-year loss in FEV1 after adjustments for confounders. There was evidence of feedback between dust-exposure levels and FEV1, indicating the existence of a healthy-worker survivor effect. After accounting for a healthy-worker survivor effect, we found a significant relationship between dust exposure and FEV1 decline. CONCLUSIONS: Our results suggest that cotton dust is more strongly associated with chronic airflow limitation than associated endotoxins. Further work is needed to clarify potential reversibility after cessation of exposure, and the relative contributions of dust, endotoxin, and tobacco to chronic respiratory impairment in cotton and other vegetable-exposed workers.

Case-Control Studies↗
PubMed1993

The worksite component of variance: design effects and the Healthy Worker Project.

Variance estimates in worksite health promotion studies depend partly on the intraclass correlation coefficient (ICC). ICC quantifies homogeneity of a variable within worksites. ICC would be zero for randomly formed worksites, but is generally positive because employees tend to share personal characteristics. The ratio comparing the variance estimated from worksite means with that estimated from individuals under simple random sampling is the design effect (DEFF). A DEFF of 1.0 indicates no excess variance due to worksite. The Healthy Worker Project (HWP) was a 32 worksite cross-sectional and longitudinal study of a weight and smoking intervention program. ICCs in cross-sectional surveys for health-related outcome variables ranged from 0.006 to 0.009, DEFFs from 2.0 to 2.6 ICCs/DEFF's in longitudinal analysis were smaller; ICCs ranged from -0.002 to 0.003, DEFFs from 0.7 to 1.5. Positive ICCs substantially increased variance estimates at a single measurement, yet variance of longitudinal analysis was less subject to worksite dependence. It is concluded the worksite component of variance is real and should not be ignored, although the worksite component of variance is small in these longitudinal analyses. This observation should be replicated before it is used in other worksite health promotion research.

Analysis of Variance↗
PubMed2005

Occupational exposure to aerosolized brevetoxins during Florida red tide events: effects on a healthy worker population.

Karenia brevis (formerly Gymnodinium breve) is a marine dinoflagellate responsible for red tides that form in the Gulf of Mexico. K. brevis produces brevetoxins, the potent toxins that cause neurotoxic shellfish poisoning. There is also limited information describing human health effects from environmental exposures to brevetoxins. Our objective was to examine the impact of inhaling aerosolized brevetoxins during red tide events on self-reported symptoms and pulmonary function. We recruited a group of 28 healthy lifeguards who are occupationally exposed to red tide toxins during their daily work-related activities. They performed spirometry tests and reported symptoms before and after their 8-hr shifts during a time when there was no red tide (unexposed period) and again when there was a red tide (exposed period). We also examined how mild exercise affected the reported symptoms and spirometry tests during unexposed and exposed periods with a subgroup of the same lifeguards. Environmental sampling (K. brevis cell concentrations in seawater and brevetoxin concentrations in seawater and air) was used to confirm unexposed/exposed status. Compared with unexposed periods, the group of lifeguards reported more upper respiratory symptoms during the exposed periods. We did not observe any impact of exposure to aerosolized brevetoxins, with or without mild exercise, on pulmonary function.

Adolescent↗
PubMed2003

Attenuation of exposure-response curves in occupational cohort studies at high exposure levels.

Numerous occupational cohort mortality studies have observed exposure-response curves to have an increasing slope at low exposure levels that attenuates or even turns negative at high exposure levels. Examples discussed in this paper include dioxin, silica, 1,3-butadiene, cadmium, beryllium, radon daughters, diesel fumes, nickel, arsenic, and hexavalent chromium. Possible explanations for this phenomenon include (i) bias introduced by the healthy worker survivor effect, (ii) a depletion of the number of susceptible people in the population at high exposure levels, (iii) a natural limit on the relative risk for diseases with a high background rate, (iv) mismeasurement or misclassification of exposures, (v) the influence of other risk factors that vary by the level of the main exposure, and (vi) the saturation of key enzyme systems or other processes involved in the development of disease.

Causality↗
PubMedDate not supplied

How safe are bioequivalence studies in healthy volunteers?

Between 1981 and 1994, 58 bioequivalence studies (b.s.) were performed in 885 healthy volunteers. 93.1 per cent were single-dose, mainly of two way cross-over design. According to ATC groups, 13 were of cardiovascular drugs(C), 11 musculoskeletal (M), nine alimentary (A), seven urogenital (G), seven antimicrobial (J), six haematological (B), three nervous (N) and two respiratory (R). 97.2 per cent of volunteers finished the studies. Out of 25 withdrawals, 14 did it by their own will, seven were excluded because of lack of compliance with the protocol, one because of an adverse drug reaction (ADR) (preputial oedema), one because of intercurrent illness, and two for other objective reasons. In 35 studies the probants have been males, in 23 both sexes. Subjects were between 18 and 40 years. 209 adverse events were reported in 18 studies (31 per cent). From 885 volunteers that came to first session at the time, 115 (13 per cent) had ADRs. The association of the drug and ADRs was defined as probable in 91 ADRs (45.9 per cent), definite in 66 (33.4 per cent) and possible in 41 (20.7 per cent). 73 (63.5 per cent) volunteers had one ADR, 22 (19.1 per cent) had two and 20 (17.4 per cent) more than two ADRs. The majority -117 (56 per cent)-of ADRs were mild, 78 (37.3 per cent) moderate and 14 (6.7 per cent) severe. The most frequent ADR was headache (22.9 per cent), followed by nasal congestion (12.9 per cent), sweating (12.4 per cent), nausea (6.7 per cent), restlessness (6.7 per cent), deafness and tinnitus (6.2 per cent), change of biochemical or haematological parameters (5.3 per cent) and other. An unusual and rare ADR was impotence and preputial oedema (two volunteers on frusemide). All studies of G group (7-100 per cent) had ADRs, followed by C group (5-38 per cent) and A (3-33 per cent). Glipizide (5 mg) had highest number of ADRs (64-30.6 per cent), bromocriptine (10 mg) had 31 (14.8 per cent) and frusemide (500 mg) 22 (10.6 per cent). The largest number of subjects with ADRs were on frusemide (13-72 per cent), glipizide (17-68 per cent) and bromocriptine (15-52 per cent). At a time when generic drugs are of increasing importance, the safety of b.s. is of considerable interest. Our data confirm their safety and indicate that the majority of ADRs are mild.

Adolescent↗
PubMedDate not supplied

Work, marital status, and heart disease.

Longitudinal data from the U.S. National Health and Nutrition Survey and its follow-up were used to analyze the effects of marriage and work roles and changes in these roles on the incidence of coronary heart conditions in a sample of 3,097 middle-aged women. Education, age, family income, race, and number of children were included as covariates. The data indicated that women who became unmarried, younger women, and better educated women were at relatively low risk, whereas women who left the labor force and women who were homemakers were at relatively high risk for the conditions. Additional analyses were done on employed women. These findings support the "well-worker effect" but cast doubt on the belief that marriage is always beneficial to health.

Adult↗
PubMed2005

Effect of job rotation on need for recovery, musculoskeletal complaints, and sick leave due to musculoskeletal complaints: a prospective study among refuse collectors.

BACKGROUND: Job rotation might be an effective preventive measure to reduce the prevalence of musculoskeletal complaints, although its effect has not been yet established. The aim of the present study is to evaluate the effect of job rotation in refuse collecting on need for recovery, prevalence of musculoskeletal complaints, and sick leave due to musculoskeletal complaints. METHODS: A 1-year prospective study among refuse collectors was performed, using standardized questionnaires. Job rotation was performed between collecting two-wheeled containers and driving a refuse truck. The experimental groups of rotating refuse collectors at t(0) and t(1) (group R-R) and non-rotating refuse collectors at t(0) and rotating refuse collectors at t(1) (group NR-R) were compared with a reference group of non-rotating refuse collectors at t(0) and t(1) (group NR-NR). RESULTS: The adjusted need for recovery of group R-R was marginally significantly lower than need for recovery of the reference group. Groups R-R and NR-R had a more than two times higher risk for complaints of the low back than the reference group. No other significant results were found. CONCLUSIONS: Job rotation seemed to coincide with a reduced need for recovery and was associated with an increased risk of low back complaints. No effects were found on sick leave due to musculoskeletal complaints. The results might be influenced by the healthy worker selection effect in the reference group and its inverse in the rotating groups.

Adult↗
PubMed1989

[Factors of random selection in epidemiological surveys].

In epidemiological surveys the association of variable under study, for example, morbidity and conditions of work, may be distorted by phenomena of selection. The most frequent effect of selection is "the effect of healthy worker" which consists in lower morbidity and mortality of workers as compared to the population at large. This effect can mask the pathogenic action of environmental conditions. Under other circumstances multiple effects of selection, on the contrary, may additionally enhance the association between morbidity and the environmental conditions. The elimination of selection errors is possible, if the analysis of data takes into account the broad range of variables capable of affecting the dependence. The issue of causative nature of dependence should be solved proceeding from the analysis of the aggregate data on the problem.

Age Factors↗
PubMed1989

Thyroid hormone economy in response to extreme cold exposure in healthy factory workers.

The effects of cold exposure on serum total T4 (TT4), total T3 (TT3), free T4 (FT4), free T3 (FT3), rT3, TSH, T4-binding globulin (TBG), and T3 resin uptake were investigated in 82 euthyroid factory workers. Twenty-five workers (group 1) were exposed intermittently (approximately 3.5 h daily) to extreme cold (-40 to -20 C) during the 8-h work shift, and 47 (group 2) were exposed to moderate cold (-10 to 8 C) for the entire 8 h. Ten individuals working at room temperature for the same period also were studied. After cold exposure, serum TT4 decreased in group 1 and did not change in group 2, whereas FT4 did not change in group 1 and increased in group 2. After exposure, serum TT3 and rT3 decreased significantly in both groups, while FT3 did not change in either. The basal serum TT4 levels in groups 1 and 2 were significantly lower than those in the control group, whereas those of FT4 and FT3 were higher. Thus, cold exposure had opposite effects on total thyroid hormones and their free fractions, consistent with a cold-induced decrease in thyroid hormone-binding capacity. A postexposure decrease in serum TBG was found in women in group 2, but not in men in either group 2 or group 1, suggesting that factors other than decreased TBG are also involved. The results suggest the possibilities that 1) decreased thyroid hormone-binding capacity is an adaptive response to cold exposure, and/or 2) increased free thyroid hormone levels in response to cold exposure result in a new higher equilibrium between extracellular and intracellular FT4 and FT3.

Adaptation, Physiological↗
PubMed1982

[Spirometric studies in clinically healthy workers in steel mills. I. Effect of age, body height and body weight on the variability of selected ventilation indicators].

Of 2750 examined workers of the Lenin steel mill a group of 520 so called healthy men aged 20-60 has been selected, who had developed chronic specific and inspecific diseases of the respiratory tract, and circulatory diseases during myocardial insufficiency and arterial hypertension. This population underwent tests performed by the F function, test of significance of differences between coefficients of multiple determination in the function of age, growth and body weight, and in the function of: age and height; age and body weight, height and body weight, which allowed to determine the contribution of age, height and body weight in the significance of the following spirometric indices: VC, FEV1%VC, RV, ERV, FRC, RV% TLC, TLC. Age exhibited statistically significant contribution to the total variance of VC, FEV1%VC, RV, ERV, FRC RV%TLC, and insignificant--in case of TLC. Height exhibits significant impace on VC, RV, ERV, FRC, TLC, RV%TLC. Statistically insignificant dependence on height was obtained in case of FEV1%VC. Inclusion of body weight showed a statistically significant explanatory value for VC, RC, ERV, FRC RV%TLC, and insignificant for TLC and FEV1%VC.

Adult↗
PubMed2006

Mortality in a Swedish rubber tire manufacturing plant: occupational risks or an "unhealthy worker" effect?

BACKGROUND: In this cohort study a classification of 12 work categories, with specified common exposures, is used to evaluate the mortality among workers in a Swedish rubber tire plant. METHODS: Mortality among the cohort members is compared with expected values from national rates. Standardized mortality ratios (SMR) were calculated for the total cohort, for sub-cohorts and with the inclusion of a latency requirement. RESULTS: Male workers had increased risks for total mortality, circulatory death, respiratory death, mental disorders, epilepsy, injuries/poisoning, and for alcohol-related death. Many risks were noted among workers exposed to dust, fumes, or vapor. No trend in risk with increasing duration of employment was seen. DISCUSSION: Some established risks for rubber workers could be related to some specified work categories. The highest risks were noted among workers having a very short duration of employment indicating a possible "unhealthy worker effect" associated with life-style factors or to tasks offered to unskilled workers.

Adult↗