Abstract

Background: The objective was to compare the pattern of exposure to second-hand smoke (SHS) among non-smokers in the general population and in hospitality workers. Methods: We used the adult (16–64 years) non-smokers of two independent studies (general population and hospitality workers) in Spain. We assessed the exposure to SHS by means of questionnaire and salivary cotinine concentration. Results: The salivary cotinine concentration by sex, age, educational level, day of week of saliva collection, and exposure to SHS were always higher in hospitality workers than in the general population. Conclusion: Our results indicated that non-smoker hospitality workers have higher levels of exposure to SHS than general population.

Introduction

Second-hand smoke (SHS) has been associated with a variety of health effects among non-smokers.1 Exposure to SHS mainly depends on exposure at home and work, and, among workers in the absence of a smoking ban in workplaces, it may vary for different occupations.2 We have recently conducted two independent studies in Spain to assess SHS exposure in non-smokers in different population groups. One study describes salivary cotinine concentration among non-smokers from the general population.3 The other study evaluates the impact of the Spanish smoking law in hospitality non-smoker workers.4 With these data, we aimed to compare the pattern of exposure to SHS among non-smokers in the general population and in hospitality workers assessed by means of salivary cotinine concentration.

Methods

We used non-smoker population within labour age (16–65 years) of these two independent studies. The first study was a cross-sectional survey conducted between March 2004 and December 2005 on a representative random sample (1245 people, 694 women and 551 men) of the non-institutionalized population of Barcelona, Spain.3 The second study was a prospective study in five regions of Spain, including 431 hospitality workers (180 women and 251 men) employed at pubs, bars, restaurants, hotels and discotheques. The follow-up period was from 2005 (before to the enactment of the Tobacco Control Law in Spain) until 2008 (2 years after the law). We used data from the baseline survey (October–December 2005).4 Both surveys were conducted before the Spanish smoking law came into effect in January 2006.5

In both studies, we obtained a saliva sample for cotinine analysis using the same protocol. Participants were asked to rinse their mouths and then suck a lemon candy (Smint®) to stimulate saliva production. Saliva samples were frozen and sent to the Bioanalysis Research Group of the Municipal Institute for Medical Research (IMIM-Hospital del Mar) in Barcelona. Salivary cotinine was measured by gas chromatography with detection by mass spectrometry (GC/MS). The limit of quantification was 1 ng/ml and the limit of detection was 0.3 ng/ml (quantification error <15%). For cotinine concentration between the limits of quantification and detection, we assigned half the level of quantification (0.5 ng/ml).

The same definition of smoking status was used in both studies. We considered as non-smoker the person who declared to have never smoked or to have formerly smoked, and had a salivary cotinine concentration compatible with non-smoking (<20 ng/ml).6,7 The final sample for this analysis consisted of 509 non-smokers from the general population and 209 non-smokers from the baseline cohort from the hospitality workers. Given the skewed distribution of cotinine concentration, we calculated geometric means and 95% confidence intervals (CIs) to describe the data. We also computed the ratios of the geometric mean of salivary cotinine concentration (hospitality workers vs. general population) to describe differences according to selected socio-demographic characteristics (i.e. sex, age, and educational level), day of the week of the saliva sample collection, and exposure to SHS at home and work.

Results

The geometric mean of cotinine concentration was 1.45 ng/ml (95% CI: 1.33–1.60 ng/ml) in the general population, and 1.95 ng/ml (95% CI: 1.78–2.14 ng/ml) in hospitality workers. Salivary cotinine concentration was higher in men as compared to women, but always higher in both men and women who were hospitality workers (ratio of geometric means were 1.30) (Table 1). Salivary cotinine concentration by sex, age, educational level, exposure to SHS at home and work and day of week were always higher in hospitality workers than in the general population (Table 1). When we restricted the general population sample to those employed men and women, we found a similar salivary cotinine concentration (overall geometric mean: 1.43 ng/ml, 95% CI: 129–1.59 ng/ml).

Table 1

Salivary cotinine concentration (ng/ml) by sex, age, educational level, SHS exposure at home and work, and day of the week of saliva sampling in non-smokers from general population and in non-smokers hospitality workers

 General population
 
Hospitality workers
 
Ratio between geometric meansa 
 n Geometric mean (95% CI) n Geometric mean (95% CI) 
All 509 1.45 (1.33–1.60) 209 1.95 (1.78–2.14) 1.34 
Sex      
    Men 210 1.62 (1.41–1.87) 126 2.10 (1.86–2.38) 1.30 
    Women 299 1.34 (1.19–1.51) 83 1.74 (1.53–1.98) 1.30 
Age (years)      
    16–44 258 1.57 (1.38–1.80) 142 1.87 (1.67–2.08) 1.19 
    45–65 251 1.34 (1.18–1.51) 59 2.07 (1.74–2.46) 1.54 
Educational level      
    Less than primary 14 0.81 (0.50–1.30) 10 2.24 (1.23–4.07) 2.77 
    Primary 148 1.38 (1.18–1.63) 69 2.22 (1.88–2.63) 1.61 
    Secondary 128 1.56 (1.29–1.88) 89 1.83 (1.59–2.11) 1.17 
    University 219 1.49 (1.30–1.72) 33 1.84 (1.54–2.22) 1.23 
Self-reported exposure to SHS at home      
    Exposed 133 1.57 (1.32–1.86) 64 2.22 (1.90–2.60) 1.41 
    Not exposed 376 1.42 (1.27–1.58) 141 1.82 (1.62–2.04) 1.28 
Self-reported exposure to SHS at workb      
    Exposed 153 1.44 (1.23–1.69) 139 2.01 (1.80–2.24) 1.40 
    Not exposed 225 1.42 (1.24–1.63) 58 1.72 (1.42–2.09) 1.21 
Day of the week of the sample collection      
    Monday 103 1.34 (1.10–1.64) 47 1.68 (1.41–2.00) 1.25 
    Tuesday 122 1.44 (1.21–1.71) 21 1.95 (1.34–2.84) 1.35 
    Wednesday 97 1.56 (1.25–1.95) 38 1.70 (1.40–2.06) 1.09 
    Thursday 96 1.44 (1.16–1.78) 41 2.15 (1.71–2.71) 1.49 
    Friday 66 1.61 (1.24–2.09) 47 2.12 (1.73–2.59) 1.32 
    Weekend 25 1.26 (0.85–1.89) 15 2.62 (1.97–3.49) 2.08 
 General population
 
Hospitality workers
 
Ratio between geometric meansa 
 n Geometric mean (95% CI) n Geometric mean (95% CI) 
All 509 1.45 (1.33–1.60) 209 1.95 (1.78–2.14) 1.34 
Sex      
    Men 210 1.62 (1.41–1.87) 126 2.10 (1.86–2.38) 1.30 
    Women 299 1.34 (1.19–1.51) 83 1.74 (1.53–1.98) 1.30 
Age (years)      
    16–44 258 1.57 (1.38–1.80) 142 1.87 (1.67–2.08) 1.19 
    45–65 251 1.34 (1.18–1.51) 59 2.07 (1.74–2.46) 1.54 
Educational level      
    Less than primary 14 0.81 (0.50–1.30) 10 2.24 (1.23–4.07) 2.77 
    Primary 148 1.38 (1.18–1.63) 69 2.22 (1.88–2.63) 1.61 
    Secondary 128 1.56 (1.29–1.88) 89 1.83 (1.59–2.11) 1.17 
    University 219 1.49 (1.30–1.72) 33 1.84 (1.54–2.22) 1.23 
Self-reported exposure to SHS at home      
    Exposed 133 1.57 (1.32–1.86) 64 2.22 (1.90–2.60) 1.41 
    Not exposed 376 1.42 (1.27–1.58) 141 1.82 (1.62–2.04) 1.28 
Self-reported exposure to SHS at workb      
    Exposed 153 1.44 (1.23–1.69) 139 2.01 (1.80–2.24) 1.40 
    Not exposed 225 1.42 (1.24–1.63) 58 1.72 (1.42–2.09) 1.21 
Day of the week of the sample collection      
    Monday 103 1.34 (1.10–1.64) 47 1.68 (1.41–2.00) 1.25 
    Tuesday 122 1.44 (1.21–1.71) 21 1.95 (1.34–2.84) 1.35 
    Wednesday 97 1.56 (1.25–1.95) 38 1.70 (1.40–2.06) 1.09 
    Thursday 96 1.44 (1.16–1.78) 41 2.15 (1.71–2.71) 1.49 
    Friday 66 1.61 (1.24–2.09) 47 2.12 (1.73–2.59) 1.32 
    Weekend 25 1.26 (0.85–1.89) 15 2.62 (1.97–3.49) 2.08 

a: Ratio = Geometric mean of hospitality workers/geometric mean of general population

b: Sample in the general population: number of subjects who declared they were working The sum does not up the total for some variables because of some missing values

In the general population, the prevalence rate of exposure to SHS was 26.1% (95% CI: 18.7–33.6%) at home and 40.5% (95% CI: 32.7–48.3%) at work. In hospitality workers, the prevalence rate of exposure to SHS was 31.2% (95% CI: 19.9–42.6%) at home and 70.6% (95% CI: 63.0–78.1%) at work. The geometric mean of salivary cotinine concentration was 1.57 ng/ml (95% CI: 1.32–1.86 ng/ml) in the general population who reported exposure to SHS at home, and 2.22 ng/ml (95% CI: 1.90–2.60 ng/ml) in hospitality workers who reported exposure to SHS at home (ratio = 1.41). The geometric mean of cotinine concentration in subjects who reported exposure to SHS at work was 1.44 ng/ml (95% CI: 1.23–1.69 ng/ml) in general population, and 2.01 ng/ml (95% CI: 1.80–2.24 ng/ml) in hospitality workers (ratio = 1.40) (Table 1).

The highest differences in the geometric means between hospitality workers and the general population were present among less-educated individuals and those aged over 45 years. In hospitality venues, the owners had higher salivary cotinine concentration than other hospitality workers (data not shown). The salivary cotinine concentration in hospitality workers was higher when the saliva sample was obtained during the weekend compared with the weekdays.

Discussion

The results of this study show that non-smoker hospitality workers are more exposed to SHS than the general population before the Spanish Tobacco Control Law. Hospitality workers have the highest levels of cotinine concentration on weekends. This could be explained because the frequency of smokers on weekends in bars, restaurants and pubs is higher than during the rest of the week. It may also be explained by the cumulative exposure during the week and is hence detected during the weekend. Interestingly, the salivary cotinine concentration among persons from the general population employed and not employed was similar. The prevalence of exposure to SHS at home was similar in the general population and in hospitality workers; however, the prevalence of exposure to SHS at work was almost 2-fold in the hospitality workers.

One limitation of this study is derived of the use of an opportunistic and non-randomized sample of hospitality workers. The use of salivary cotinine as a specific biomarker of exposure to SHS in the previous 2–5 days6,8,9 in both studies is one of the strengths of this report. Moreover, the analytical method to evaluate salivary cotinine is highly sensitive; assessment of cotinine concentration was blind to the participants’ smoking status, and the same protocol was used for all saliva samples in the two studies.3,4

In conclusion, this study shows that exposure to SHS was higher in non-smoker hospitality workers than in non-smokers from the general population, in terms of sex, age, educational level, exposure to SHS at home and work and day of week of saliva collection, before a national ban on smoking came into effect in Spain.5,10 Therefore, these employees are subject to a higher health risk in terms of lung cancer, ischaemic heart disease and respiratory symptoms due to their occupational exposure to SHS.

Funding

The Instituto de Salud Carlos III (FIS PI020261, FIS PI052072, and the Thematic Network of Cooperative Research on Cancer RD06/0020/0089) from the Government of Spain; the Ministry of Universities and Research (2009SGR192), Government of Catalonia; and the “V Ayuda Enrique Nájera para jóvenes epidemiólogos” of the Spanish Society of Epidemiology funded by the Escuela Nacional de Sanidad.

Conflicts of interest: None declared.

Key points

  • Exposure to SHS was higher in non-smoker hospitality workers than in non-smokers from the general population before a national ban on smoking came into effect in Spain.

  • Smoking control law must protect all workers without exceptions from exposure to SHS including hospitality workers.

Acknowledgements

We acknowledge the collaboration of all participants. We thank Chupa Chups Spain for providing the Smint® candies in both studies.

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Appendix 1: Determinants of COTinine (DCOT) Study investigators

Antoni Agudo, Carles Ariza, Josep M. Borràs, Esteve Fernández, Marcela Fu, Mireia Jané, Jose M. Martínez-Sánchez, Albert Moncada, Manel Nebot, José A. Pascual, Mercè Peris, Esteve Saltó, Jonathan M. Samet, Anna Schiaffino, Jorge Twose.

The Spanish Smoking Law Evaluation Group

Institut Català d’Oncologia: Esteve Fernández (principal investigator), Marcela Fu, Jose M. Martínez-Sánchez, Anna Martín, Josep M. Borràs, Stephanie Rania, Jorge Twose, Anna Schiaffino;

Agència de Salut Pública de Barcelona: Manel Nebot and Carles Ariza (principal investigators), María J. López, Francesca Sánchez-Martínez, Francesc Centrich, Glòria Muñoz, Eulàlia Serrahima;

Generalitat de Catalunya: Esteve Saltó (study co-ordinator), Araceli Valverde, Meia Faixedas, Francesc Abella, Enric Rovira;

IMIM-Hospital del Mar: José Antonio Pascual, Raúl Pérez;

Xunta de Galicia: Mónica Pérez-Ríos (study co-ordinator), Begoña Alonso, María Isolina Santiago, María Jesús García, Míriam Otero;

Govern de les Illes Balears: Arturo López (study co-ordinator), Elena Tejera, Magdalena Borrás, Juan A. Ayensa, Ernesto Pérez;

Generalitat Valenciana: Francisco Carrión (study co-ordinator), Pepa Pont, José A. Lluch, Elena Pérez;

Gobierno de Cantabria: M. Eugenia López (study co-ordinator), Sonia Álvarez, M. Emma del Castillo, Fernando Martín, Blanca M. Benito;

Junta de Extremadura: José Antonio Riesco (study co-ordinator);

Comunidad de Madrid: Isabel Marta (study co-ordinator), Almudena García, Carmen Estrada, Virgilio Blanco;

Gobierno de La Rioja: Ana Esteban (study co-ordinator), M. Ángeles Hessel;

Universidade do Minho: José Precioso (study co-ordinator);

Acadèmia de Ciències Mèdiques d’Andorra: Margarida Coll (study co-ordinator).

Author notes

* See Appendix 1 for the full list of members

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