Association of perfluoroalkyl substances exposure with impaired lung function in children

Highlights

• Little research exists on the relationship between PFASs exposure and lung function.

• Association of serum PFASs with lung function was assessed in high exposure children.

• PFASs were positively associated with impaired lung function in children.

• The association was significant only in asthmatic children.

Abstract

Previous studies have demonstrated associations between serum levels of perfluoroalkyl substances (PFASs) and asthma or asthma related-biomarkers. However, no studies have reported a possible relationship between PFASs exposure and lung function among children. The objective of the present study is to test the association between PFASs exposure and lung function in children from a high exposure area by using a cross-sectional case-control study, which included 132 asthmatic children and 168 non-asthmatic controls recruited from 2009 to 2010 in the Genetic and Biomarkers study for Childhood Asthma. Structured questionnaires were administered face-to-face. Lung function was measured by spirometry. Linear regression models were used to examine the influence of PFASs on lung function. The results showed that asthmatics in our study had significantly higher serum PFAS concentrations than healthy controls. Logistic regression models showed a positive association between PFASs and asthma, with adjusted odds ratios (ORs) ranging from 0.99 (95% confidence interval [CI]: 0.80–1.21) to 2.76 (95% CI: 1.82–4.17). Linear regression modeling showed serum PFASs levels were significantly negatively associated with three pulmonary function measurements (forced vital capacity: FVC; forced expiratory volume in 1 s: FEV₁; forced expiratory flow 25–75%: FEF_25–75) among children with asthma, the adjusted coefficients between lung function and PFASs exposure ranged from −0.055 (95%CI: −0.100 to −0.010) for FVC and perfluorooctane sulfonate (PFOS) to −0.223 (95%CI: −0.400 to −0.045) for FEF_25–75 and perfluorooctanoic acid (PFOA). PFASs were not, however, significantly associated with pulmonary function among children without asthma. In conclusion, this study suggests that serum PFASs are associated with decreased lung function among children with asthma.

Introduction

Asthma is one of the most common chronic diseases throughout the world, especially among children (Lai et al., 2009). Although many asthma risk factors have been identified, reasons for its rising prevalence remain poorly understood (Beasley et al., 2015) and emerging environmental exposures may bear a portion of the attributable risk (Guarnieri and Balmes, 2014, Miller and Marty, 2010).

Perfluoroalkyl substances (PFASs) are a diverse class of chemicals with unique properties like extremely high thermal and chemical stability. They have long serum half-lives (in years) of 5.4 (perfluorooctane sulfonate, PFOS), 3.8 (perfluoronanoic acid, PFOA), and 8.3 (perfluorohexanesulfonate, PFHxS) years (Buck et al., 2011, Olsen et al., 2007). These properties are responsible for the accumulation of PFASs in the environment, wildlife, and humans (Fromme et al., 2007, Schecter et al., 2012, Zhou et al., 2014), but also make them ideal for applications such as firefighting foams, paints, semiconductors, photographic films, and pesticides, for which they have been widely used since the 1950s (Lindstrom et al., 2011). In addition, both human and animal studies have found that the lungs are likely a target organ of PFASs (Borg et al., 2010, Perez et al., 2013).

Animal evidence indicates that exposure to PFOA and PFOS cause a variety of asthma-related outcomes. Fairley et al. (2007) revealed that PFOA caused increased serum immunoglobulin E (IgE) and an exaggerated response to ovalbumin. The evidence suggests exposure to PFOA may intensify the IgE response to allergens in a murine model of asthma (Fairley et al., 2007). Furthermore, two animal studies show that prenatal PFOA and PFOS exposure may adversely affect lung development (Loewen et al., 2011, Ryu et al., 2014). One study noted that PFOS exposure lowered baseline airway resistance but significantly increased airway responsiveness in an allergic murine model of pups (Loewen et al., 2011). Another study did not identify maternal exposure to PFOA or PFOS as a risk factor for more severe asthma-like symptoms in pups, but found that PFOA induced airway inflammation and altered airway function (Ryu et al., 2014).

Epidemiologic evidence suggests that exposure to PFASs is positively associated with asthma, but results are inconsistent. Dong et al. (2013) reported a positive association between PFASs and asthma, asthma severity, and immune markers in Taiwanese children. Using 1999–2000 and 2003–2008 National Health and Nutrition Examination Survey (NHANES) data, Humblet et al. (2014) provided modest evidence for positive associations between exposure to PFASs and asthma-related outcomes among children. In the INUENDO birth cohort study from Greenland and Ukraine, however, Smit et al. (2015) did not find an association.

No study has examined whether PFAS exposure is associated with objective measures of lung function such as spirometry, which provides information on airway obstruction by measuring forced expiratory volume in one second (FEV₁), forced vital capacity (FVC), peak expiratory flow rate (PEF), and forced expiratory flow at 25–75% of FVC (FEF_25–75) (Pellegrino et al., 2005). These tools not only have utility for diagnosing and monitoring asthma (Gaffin et al., 2010, Pijnenburg et al., 2015), but also are the most commonly employed pulmonary function tests for assessing effects of environmental chemicals on lung function (Barraza-Villarreal et al., 2008, Miller and Marty, 2010). The objective of the present study was to test the association between PFAS exposure and lung function in a case-control study of asthmatic and non-asthmatic children, by using data from the Genetic and Biomarkers study for Childhood Asthma (GBCA).