Rethinking Cumulative Exposure in Epidemiology Again

Abstract

Purpose

To report respiratory effects of exposure to soft paper grit exposure, a relationship that is rarely studied.

Methods

Soft tissue paper manufactory workers at a Swedish newspaper mill were investigated using a questionnaire and lung function and atopy screening. Spirometry without bronchodilation was performed with a dry wedge spirometer, and forced vital capacity (FVC) and forced expiratory volume in i s (FEV₁) were obtained and expressed as percent predicted. Exposure to soft paper grit was assessed from historical stationary and personal measurements of total dust, in addition to historical information almost the work, department, and production. The bear upon of high exposure to soft newspaper dust (> five mg/m^three) vs. lower exposure ≤ 5 mg/kⁱⁱⁱ, as well as cumulative exposure, was analyzed using multiple linear regression models. Multivariate models were adjusted for smoking, atopy, gender, and trunk mass index.

Results

I hundred ninety-eight current workers (124 male and 74 female) were included. In that location were pregnant associations between both cumulative exposure and years of high exposure to soft paper dust and impaired lung part. Each twelvemonth of high exposure to soft paper dust was associated with a 0.87% subtract in FEV_one [95% confidence interval (CI) − 1.39 to − 0.35] and decreased FVC (− 0.54%, 95% CI − i.00 to − 0.08) compared to the lower exposed workers.

Conclusions

The present study shows that occupational exposure to soft newspaper grit (years exceeding 5 mg/mⁱⁱⁱ total dust) is associated with lung function impairment and increased prevalence of obstructive lung function impairment.

Introduction

Occupational exposure to grit, both organic and inorganic, is conspicuously associated with lung part impairments and clinical outcomes similar chronic obstructive pulmonary disease (COPD) and interstitial lung disease (Blanc et al. 2019). The lurid and paper industry is an important industrial sector in Sweden, and a large sector is the production of soft paper (FAO 2017). Growth in demand for particularly soft newspaper, i.e., toilet paper, paper towels, and napkins has been particularly strong in Asia (CEPI 2017). Soft paper mills however take high exposure to grit, and in previous decades, dust levels accept frequently exceeded 10 mg/m³. Soft paper dust is an organic grit with a varying proportion of inorganic material depending on the use of additives (Sahle et al. 1990). In animate being models, it has been shown that fibers from cellulose are biopersistent, and information technology has also been shown that exposure to cellulose grit are associated with fibrotic and granulomatous reactions (Muhle et al. 1997, Tatrai et al. 1996). Hence, it seems reasonable exposure to soft paper dust should be associated with dumb lung role.

Nosotros have in previous studies shown that high occupational exposure (> v mg/chiliad^three) to soft paper grit is associated with impaired lung function, mainly decreased forced expiratory volume in one due south (FEV_i) and forced vital capacity (FVC) (Ericsson et al. 1988; Järvholm et al. 1988). A German study, also on soft paper mill workers with occupational exposure (> five mg/yard³) to soft paper dust, observed a dose–response relationship for cumulative exposure to soft newspaper dust and decreased FVC (Kraus et al. 2004). By contrast, in 2 studies with lower exposure levels (≤ 5 mg/mⁱⁱⁱ), there was no association between exposure to soft paper dust and lung role harm (Heederik et al. 1987; Thorén et al. 1989b). There is besides conflicting data most whether exposure to paper grit increases the risk for asthma and COPD (Thorén et al. 1989a; Torén et al. 1991, 1994, 1996). Hence, there is an obvious need for further studies investigating the relation between exposure to soft tissue paper grit and respiratory health furnishings, especially lung part outcomes.

In this study, we have examined workers in a large soft tissue paper mill in Sweden with the aim to elucidate the extent to which exposure to soft newspaper dust is associated with respiratory health effects.

Materials and methods

The study was performed at a manufacturing plant where soft tissue paper production started on a small scale in 1948, and increased considerably around 1960. Today, the mill is one of the largest soft paper plants in Sweden. In 2006, all employees currently working at the manufacturing plant (north = 205) were invited to participate in a clinical investigation at the manufacturing plant site. Six of the invited persons did not participate. Hence, the initial study population included 199 workers.

All invited workers received an all-encompassing questionnaire with questions almost occupational history, smoking habits, and respiratory symptoms and asthma. Height and weight were measured with workers wearing light clothing and no shoes. Spirometry without bronchodilation was performed with a dry wedge spirometer (Vitalograph, Buckingham, United kingdom of great britain and northern ireland) and according to American Thoracic Society (ATS)/European Respiratory Gild (ERS) standards (Miller et al. 2005). Forced vital capacity and FEV₁ were measured with individuals in a sitting position and wearing a nose prune, and predicted normal values were based on the GLI-equations (Quanjer et al. 2012). Blood samples were analyzed for specific immunoglobulin E class using Phadiatop assay (Pharmacia & Upjohn Diagnostics, Uppsala, Sweden).

Definitions

Dissimilar definitions of airflow limitation (AL) were used: AL_GOLD was divers, co-ordinate to Global Initiative for Obstructive Lung Disease (GOLD) criteria, as an FEV_ane/FVC ratio of < 0.7 (Vogelmeier et al. 2017); AL_LLN was defined as an FEV₁/FVC ratio below the lower limit of normal (LLN₅) (Quanjer et al. 2012). Restrictive spirometric blueprint was divers every bit FEV_ane/FVC > 0.vii and FVC < 80% predicted (Crapo 1994).

Smoking was classified as never-smoking, sometime smoking, and current smoking, based on the subjects' answers to the questionnaire. Pack-years were calculated among current and former smokers. Asthma was defined equally an affirmative answer to "Have you ever had asthma diagnosed by a physician?" and onset afterward 15 years of age (Torén et al. 1993). Cough with phlegm (chronic bronchitis) was defined as an affirmative answer to "Take you had long-standing cough with phlegm?" and "If and so, did any menstruation last at least 3 months?" and "If so, accept you had such periods at least two years in a row?" (Holm et al. 2014). Wheezing was defined every bit an affirmative answer to the question "Have you experienced wheeze or whistling in your chest at whatsoever time since xv years of historic period?" Atopy was defined every bit a positive Phadiatop result (grade one) (Matricardi et al. 1990). Body mass alphabetize (BMI) was defined every bit measured weight/height².

Exposure assessments

For the purpose of this study, we adult a specific job exposure matrix (JEM) for soft paper dust exposure. Exposure to soft newspaper grit was assessed from historical stationary and personal measurements of total grit, in addition to historical information well-nigh the work, department where worked, and kind of production, allowing us to appraise exposure to soft newspaper dust for every year for each worker with an estimated mean level of grit (mg/thou³). Further, the cumulative exposure, in mg/m³-years, was calculated for each worker, as (mg/thousandⁱⁱⁱ) × years of exposure. Due to variations in exposure across time and duties, most workers were classified into more than one exposure category over the study menstruum. The cumulative number of years in different exposure categories is shown in Table 1. Cumulative mg/k³-years for all workers were divided into quartiles and workers in the highest quartile (> 72 mg/k³-years) were defined every bit loftier exposed. The remaining workers were classified as lower exposed. High exposed years were divers every bit years having been exposed to soft newspaper dust exceeding five mg/grand³.

Table 1 Categories of exposure to soft tissue paper dust by cumulative number of years of exposure working at the manufactory

Full size table

Statistical analyses

In the univariate analyses, we dichotomized the subjects into high exposed and lower exposed to soft paper grit. Univariate inferential analyses were performed using Chi-foursquare exam and Student's t test. Where there were fewer than ten subjects in any stratum, Fisher'due south exact test was used for univariate analyses. Univariate analysis results were considered significant if p < 0.05.

Lung role outcomes (dependent variable) and the association between the different independent variables (gender, BMI, pack-years, current smoking, atopy, and soft paper dust exposure) were examined in multiple linear regression models, and also stratified into never-smoking and e'er-smoking. The associations between high exposure (highest quartile of cumulative grit exposure) and AL_GOLD, AL_LLN, asthma, chronic bronchitis, and wheezing were analyzed using logistic regression models. Grit exposure was measured in terms of loftier exposed years as well every bit the cumulative exposure measure, mg/chiliadⁱⁱⁱ-years. All variables were kept in the models even if nearly of them were without formal statistical significance. The models were adapted for former and electric current smoking and also stratified into never-smoking and ever-smoking. In all regression models, we used 95% conviction intervals (CIs) and p values to determine significance. All analyses were performed using SAS version nine.iv (SAS, Cary, NC, USA).

Results

Ane person was excluded due to inadequate spirometry technique; hence, the final study population comprised 198 workers with complete data regarding lung function and smoking habits. Basic data of the study population are shown in Table 2. In the univariate analyses, FEV_i was significantly lower among the high exposed compared to the lower exposed workers, 91.iv% vs. 97.8% predicted. Further, the prevalence of both AL_Gilt and AL_LLN was higher (p < 0.05) among the high exposed workers, 27.5% vs. 6.eight%, and 19.half-dozen% vs. 6.1%, respectively.

Table 2 Personal data age, gender, employment time, every bit well as data on respiratory health, smoking habits, pulmonary function, and dust exposure data in soft tissue paper mill workers

Full size table

In adapted multiple linear regression models, lung role decreased for every loftier exposed year (Table 3). For each year of exposure to high levels of soft paper grit, there was a 0.87% predicted decrease in FEV₁ (95% CI − 1.39 to − 0.35). A similar, but lesser, event was seen for FVC (− 0.54% predicted, 95% CI − ane.00 to − 0.08). Among never-smokers, the exposure effect was significant but with regard to FVC (− 1.33% predicted, 95% CI − 2.50 to − 0.16) (Table three). Cumulative exposure to soft paper dust expressed equally mg/1000³-years was associated with decreased FEV₁ and decreased FVC (Table three). This was seen among all workers and amidst always-smokers. Amidst never-smokers the estimates also indicated decreased FEV_one and FVC, but without formal statistical significance.

Table 3 Multivariate linear regression analyses of lung role, in percent of predicted values, among subjects currently employed (n = 198) at a soft tissue paper mill in Sweden

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In the logistic regression models, loftier exposure to soft paper dust was associated with an increased odds ratio (OR) both for AL_Gold (OR iv.6, 95% CI ane.8–12.0) for AL_LLN (OR 3.four, 95% CI i.ii–nine.iii) (Table 4). At that place were no significant associations with asthma, wheezing, or chronic bronchitis (Table 4).

Table 4 Logistic regression models of developed-onset asthma, wheeze, chronic bronchitis, and lung office parameters amid subjects (due north = 198) currently employed at a soft tissue paper mill in Sweden

Full size table

Discussion

The main finding from this study is that high exposure to soft paper dust (> v.0 mg/m^three) was associated with decreased pulmonary part. Previous studies take indicated restrictive lung function impairment associated with paper dust exposure; past contrast, the results from this study indicated obstructive impairment, as FVC was less affected than FEV₁, and the prevalence of AL was increased amid high exposed workers.

Our previous written report, showing a restrictive impairment of lung office, was conducted at paper mills with dust levels often exceeding ten mg/m³; hence, probably higher than the exposure, present and by, at the manufacturing plant in this report (Järvholm et al. 1988). In the present manufactory, the levels in the 1980s were between 5 and x mg/yard³ total dust, but exposure levels were subsequently reduced to around ane–2 mg/m³ (Thorén et al. 1989b). By analyzing the association between lung function and high exposed years, we consider both the intensity and the duration of exposure (De Vocht et al. 2015). Our findings in the present study signal that working for at least 1 year at dust levels exceeding 5.0 mg/m³ is associated with significant lung function impairment. Such high exposure levels have not been present in the factory in the terminal two decades; hence, the afflicted workers have had quite a long exposure to soft newspaper grit. However, low exposed workers with a similar elapsing of exposure did not prove any signs of lung function impairment. Amidst never-smokers FVC was significantly decreased, − 1.30% predicted but FEV₁ was not significantly affected.

Chronic airflow limitation (CAL), is unremarkably defined as an FEV₁/FVC ratio of < 0.7 (Vogelmeier et al. 2017). This has been seriously challenged, nonetheless, because the fixed ratio FEV₁/FVC < 0.7 does not accept into account the age-related changes in lung role. Thus, it has been argued that employing a definition based on FEV₁/FVC < 0.7 leads to an overestimation of airflow limitation in the older population (Pellegrino et al. 2005). An alternative approach that has been proposed is to use the LLN as a cutting-off. The LLN is calculated using the distribution in reference material; the use of LLN has been proposed by the ATS/ERS (Pellegrino et al. 2005). However, every bit we only had access to spirometry without bronchodilation, we analyzed AL equally a proxy for CAL. However, we observed, as expected, that the prevalence of AL_GOLD was college (12.1%) than the prevalence of AL_LLN (9.vi%).

We decide to nowadays both AL_Gilt and L_LLN equally a joint American Thoracic Order/European Respiratory Society (ATS/ERS) statement called for investigations of comparisons between the fixed cut-off (FEV₁/FVC < 0.seven) and the LLN-based definition (FEV₁/FVC < LLN) of airflow limitation in predicting adverse health outcomes (Celli et al. 2015). Our results also indicated that both definitions predicted an agin issue.

Whether soft newspaper grit exposure increases obstructive lung disease risk is unclear. Among soft tissue paper workers, we have previously described increased mortality due to obstructive lung disease as well as an insignificantly increased incidence charge per unit of asthma (Thorén et al. 1989a; Torén et al. 1994). In addition, soft paper workers seem to have an increased prevalence of rhinitis and irritative symptoms of the upper airways, even those exposed to levels below 5 mg/m³ (Thorén et al. 1989b; Hellgren et al. 2001; Kraus et al. 2002, Holm et al. 2011). Amongst more highly exposed workers, increased prevalence of coughing has been reported (Torén et al. 1994; Kraus et al. 2002). A suspected case of occupational asthma due to cellulose has also been described (Knight et al. 2018). Our results provide further prove that high exposure to soft paper dust has irritating effects on the airways, impairs lung function and increases the risk for AL, regardless of how this is divers. In a longer perspective exposure to soft newspaper dust may also increase the risk for COPD (Järvholm 2000).

We also intended to ascertain a grouping of workers with restrictive spirometric design, but the prevalence was too depression to perform whatsoever meaningful analyses.

The present report has a number of methodological limitations that accept to be considered. The primary limitation is the cantankerous-sectional design. This design implies that workers with long-standing respiratory ailments may have left the mill. Nosotros have previously shown that subjects with asthma or respiratory symptoms accept an increased frequency of chore modify (Torén et al. 2009). This turnover of workers will cause an underestimation of the risk associated with paper grit exposure, due to good for you worker pick bias (Östlin 1989). The reference group in the nowadays study was not unexposed; rather, they were low exposed workers, which may likewise have resulted in underestimation.

Our assay adjusted for current smoking and cumulative dose of tobacco (pack-years). At that place is, however, a potent relation between decreased FEV₁ and increased prevalence of AL and tobacco smoking, and, hence, residual misreckoning past smoking cannot be excluded.

Another major limitation is the lack of power. The study size was express to the workforce in one mill, which limited the number of study subjects. Still, there were meaning associations between exposure and the lung function parameters.

Conclusions

The nowadays written report shows that occupational exposure to soft paper dust (years exceeding 5 mg/m³ total dust) is associated with lung function harm and increased prevalence of obstructive lung part harm.

References

• Blanc PD, Annesi-Maesano I, Balmes JR et al (2019) The occupational burden of non-malignant respiratory diseases. An official American Thoracic Society and European Respiratory Society Statement. Am J Respir Crit Care Med 199:1312–1334

  Article  Google Scholar

• Celli BR, Decramer Yard, Wedzicha JA et al (2015) An official American Thoracic Gild/European Respiratory Social club argument: Inquiry questions in COPD. Eur Respir J 45:879–905

  Commodity  Google Scholar

• CEPI (2017) Fundamental statistics. European Pulp and Paper Industry. CEPI, Brussels

  Google Scholar

• Crapo R (1994) Pulmonary-function testing. North Engl J Med 331:25–30

  CAS  Article  Google Scholar

• De Vocht F, Burstyn I, Sanguanchaiyakrit N (2015) Rethinking cumulative exposure in epidemiology, again. J Expo Sci Environ Epidemiol 25(5):467–473

  Article  Google Scholar

• Ericsson J, Järvholm B, Norin F (1988) Respiratory symptoms and lung role following exposure in workers exposed to soft paper tissue dust. Int Arch Occup Environ Health 60(5):341–345

  CAS  Article  Google Scholar

• FAO (2017) Pulp and paper capacities survey 2016–2021. FAO, Rome

  Google Scholar

• Heederik D, Burdorf L, Boleij J, Willems H, van Bilsen J (1987) Pulmonary office and intradermal tests in workers exposed to soft-paper dust. Am J Ind Med eleven(6):637–645

  CAS  Article  Google Scholar

• Hellgren J, Eriksson C, Karlsson G, Hagberg S, Olin A-C, Torén Thousand (2001) Nasal symptoms among workers exposed to soft paper grit. Int Arch Occup Environ Health 74(2):129–132

  CAS  Article  Google Scholar

• Holm M, Dahlman-Höglund A, Torén Yard (2011) Respiratory wellness effects and exposure to superabsorbent polymer and paper dust—an epidemiological study. BMC Public Wellness 11:557

  Commodity  Google Scholar

• Holm M, Torén K, Andersson Due east (2014) Incidence of chronic bronchitis: a prospective report in a large full general population. Int J Turberc Lung Dis 18:870–875

  CAS  Commodity  Google Scholar

• Järvholm B (2000) Natural organic fibers—health effects. Int Curvation Occup Environ Health 73(Suppl):S69–S74

  Article  Google Scholar

• Järvholm B, Thorén Yard, Brolin I, Ericson J, Morgan U, Tylén U, Bake B (1988) Lung function in workers exposed to soft paper dust. Am J Ind Med 14(4):457–464

  Article  Google Scholar

• Knight D, Lopata AL, Nieuwenhuizen N, Jeebhay M (2018) Occupational asthma associated with bleached chlorine-free cellulose dust in a sanitary pad production constitute. Am J Ind Med 61:952–958

  CAS  Article  Google Scholar

• Kraus T, Pfahlberg A, Gefeller O, Raithel HJ (2002) Respiratory symptoms and diseases among workers in the soft tissue producing manufacture. Occup Environ Med 59(12):830–835

  CAS  Commodity  Google Scholar

• Kraus T, Pfahlberg A, Zöbelein P, Gefeller O, Raithel HJ (2004) Lung part among workers in the soft tissue paper-producing manufacture. Chest 125(ii):731–736

  Article  Google Scholar

• Matricardi PM, Nisini R, Pizzolo JG, D'Amelio R (1990) The utilize of Phadiatop in mass-screening programmes of inhalant allergies: advantages and limitations. Clin Exp Allergy twenty(2):151–155

  CAS  Article  Google Scholar

• Miller MR, Hankinson J, Brusasco Five, Burgos F, Casaburi R, Coates A et al (2005) ATS/ERS Task Force. Standardisation of spirometry. Eur Respir J 26:319–338

  CAS  Article  Google Scholar

• Muhle H, Ernst H, Bellmann B (1997) Investigation of the durability of cellulose fibers in rat lungs. Ann Occup Hyg 41:184

  Google Scholar

• Östlin P (1989) The, "health-related selection effect" on occupational morbidity rates. Scand J Soc Med 17:265–270

  Article  Google Scholar

• Pellegrino R, Viegi Yard, Brusasco Five, Crapo RO, Burgos F, Casaburi R et al (2005) Interpretative strategies for lung part tests. Eur Respir J 26(5):948–968

  CAS  Article  Google Scholar

• Quanjer PH, Stanojevic S, Cole TJ et al (2012) ERS Global Lung Function Intiative. Multi-ethnic reference values for spirometry for the three-95-yr age range: the global lung function 2012 equations. Eur Respir J 2012(40):1324–1343

  Commodity  Google Scholar

• Sahle W, Sällsten Grand, Torén K (1990) Characterization of airborne dust in a soft paper manufactory. Ann Occup Hyg 34:55–75

  CAS  Google Scholar

• Tatrai E, Brozik K, Adamis Z et al (1996) In vivo pulmonary toxicity of cellulose in rats. J Appl Toxicol 16:129–135

  CAS  Article  Google Scholar

• Thorén M, Järvholm B, Morgan U (1989a) Mortality from asthma and chronic obstructive pulmonary disease amongst workers in a soft paper mill: a case–referent report. Br J Ind Med 46(three):192–195

  Google Scholar

• Thorén K, Sällsten Grand, Bake B, Drake U, Järvholm B, Sahle West (1989b) Lung function and respiratory symptoms among workers in a soft paper mill. Int Arch Occup Environ Wellness 61(seven):467–471

  Commodity  Google Scholar

• Torén K, Sällsten G, Järvholm B (1991) Bloodshed from asthma, chronic obstructive pulmonary disease, respiratory arrangement cancer, and breadbasket cancer amongst paper manufacturing plant workers: a case–referent study. Am J Ind Med nineteen:729–737

  Article  Google Scholar

• Torén K, Brisman J, Järvholm B (1993) Asthma and asthma-like symptoms in adults assessed by questionnaires. Chest 104:600–608

  Article  Google Scholar

• Torén M, Järvholm B, Sällsten One thousand, Thiringer G (1994) Respiratory symptoms and asthma among workers exposed to paper dust: a accomplice study. Am J Ind Med 26(4):489–496

  Commodity  Google Scholar

• Torén K, Hagberg Due south, Westberg H (1996) Health furnishings of working in pulp and paper mills: exposure, obstructive airways diseases, hypersensitivity reactions, and cardiovascular diseases. Am J Ind Med 29(2):111–122

  Article  Google Scholar

• Torén K, Zock J-P, Kogevinas Chiliad et al (2009) An international prospective general population-based study of respiratory work inability. Thorax. 64(4):339–344

  Article  Google Scholar

• Vogelmeier CF, Criber GJ, Martinez FJ, Anzueto A, Barnes PJ, Bourbeau J et al (2017) Global strategy for the diagnosis, management, and prevention of chronic obstructive lung disease report. Golden Executive summary. Am J Respir Crit Care Med 195:557–582

  CAS  Article  Google Scholar

Download references

Acknowledgements

Open access funding provided by University of Gothenburg.

Funding

This study was supported by the Swedish Quango for Working Life and Social Enquiry, the Swedish Heart and Lung Foundation and by grants from the Swedish state under the agreement between the Swedish government and the county councils, the ALF-understanding, 74570.

Author data

Affiliations

1. Occupational and Environmental Medicine, Sahlgrenska University and University Infirmary, Box 414, 405 xxx, Göteborg, Sweden

   Eva Andersson, Gerd Sällsten, Susanna Lohman & Kjell Torén

2. Department of Environmental Health Sciences, University of Michigan, Ann Arbor, MI, Usa

   Richard Neitzel

Corresponding author

Correspondence to Kjell Torén.

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The authors declare that they have no disharmonize of interest.

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All procedures performed in the present study were in accordance with the ethical standards of the national inquiry commission, the Gothenburg Ethical Committee, Dnr 113-05), and with the 1964 Helsinki declaration and its afterward amendments or comparable ethical standards.

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Andersson, East., Sällsten, 1000., Lohman, S. et al. Lung function and paper dust exposure among workers in a soft tissue paper mill. Int Curvation Occup Environ Health 93, 105–110 (2020). https://doi.org/10.1007/s00420-019-01469-6

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• Received: xiii March 2019

• Accepted: 14 Baronial 2019

• Published: 26 August 2019

• Issue Date: Jan 2020

• DOI : https://doi.org/x.1007/s00420-019-01469-6

Keywords

• Obstructive lung disease
• Occupational
• COPD
• Organic dust

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