Phthalate Exposure and Allergy in the US Population
Background: Environmental exposures to phthalates, particularly high-molecular-weight (HMW) phthalates, are suspected to contribute to allergy.
Objective: We assessed whether phthalate metabolites are associated with allergic symptoms and sensitization in a large nationally representative sample.
Methods: We used data on urinary phthalate metabolites and allergic symptoms (hay fever, rhinitis, allergy, wheeze, asthma) and sensitization from participants ≥ 6 years of age in the National Health and Nutrition Examination Survey (NHANES) 2005–2006. Allergen sensitization was defined as a positive response to at least one of 19 specific IgE antigens (≥ 0.35 kU/L). Odds ratios (ORs) per one log10 unit change in phthalate concentration were estimated using logistic regression adjusting for age, race, body mass index, gender, creatinine, and cotinine. Separate analyses were conducted for children (6–17 years of age) and adults.
Results: The HMW phthalate metabolite monobenzyl phthalate (MBzP) was the only metabolite positively associated with current allergic symptoms in adults (wheeze, asthma, hay fever, and rhinitis). Mono-(3-carboxypropyl) phthalate and the sum of diethylhexyl phthalate metabolites (both representing HMW phthalate exposures) were positively associated with allergic sensitization in adults. Conversely, in children, HMW phthalate metabolites were inversely associated with asthma and hay fever. Of the low-molecular-weight phthalate metabolites, monoethyl phthalate was inversely associated with allergic sensitization in adults (OR = 0.79; 95% CI: 0.70, 0.90).
Conclusion: In this cross-sectional analysis of a nationally representative sample, HMW phthalate metabolites, particularly MBzP, were positively associated with allergic symptoms and sensitization in adults, but there was no strong evidence for associations between phthalates and allergy in children 6–17 years of age.
Phthalates are common industrial chemicals used in cosmetics, personal care products, plastics, and building materials. Exposures are frequent, but the contributions of specific sources are poorly characterized. Phthalates represent a broad chemical class that includes both low-molecular-weight (LMW) compounds such as diethyl phthalate (DEP) and relatively high-molecular-weight (HMW) compounds such as diethylhexyl phthalate (DEHP) and butylbenzyl phthalate (BBzP). LMW phthalates are most commonly found in cosmetics and personal care products, whereas HMW phthalates are most associated with plastics, particularly polyvinyl chloride (PVC) building materials (Buckley et al. 2012; Carlstedt et al. 2012; Hauser and Calafat 2005). Results from dietary intervention studies suggest that food packaging is the primary source of human exposure to DEHP, but not BBzP (Koch et al. 2013; Rudel et al. 2011). BBzP exposure is associated with PVC flooring and other building materials in the home (Carlstedt et al. 2012).
Phthalates and other plasticizing chemicals have been associated with wheeze, allergies, and asthma among children (Bornehag and Nanberg 2010; Bornehag et al. 2004; Choi et al. 2010; Hsu et al. 2011; Just et al. 2012a, 2012b; Kolarik et al. 2008; Larsson et al. 2007) and adults (Jaakkola and Knight 2008; Jaakkola et al. 2006). Recent studies have measured phthalate levels in urine or dust, although earlier studies suggested a role for phthalates due to the presence of plastic materials in the home (Jaakkola and Knight 2008; Larsson et al. 2007), exposure to PVC plastics in an occupational setting (Jaakkola and Knight 2008) or use of synthetic bedding (Ponsonby et al. 2003). As the evidence for a potential role for phthalates in respiratory and allergic outcomes has increased, there is greater interest in HMW phthalates such as DEHP and BBzP, with evidence both from human and animal studies (Dearman et al. 2009; Deutschle et al. 2008; Jaakkola and Knight 2008; Koike et al. 2009; Larsen et al. 2007; Nishioka et al. 2012). These HMW phthalates alter immune responses in animal and in vitro models (Koike et al. 2009; Larsen et al. 2007). In addition, other studies suggest that DEHP and other plasticizers may act as adjuvants to enhance the allergic response (Kimber and Dearman 2010).
Recent reports have stressed the need to understand the potential allergic health effects of phthalates (Dodson et al. 2012; Hulin et al. 2012; Kwak et al. 2009). Although some evidence suggests a role of phthalates in the etiology of allergic sensitization and allergic symptoms, there is a paucity of population-based data, particularly among adults. To address this, we evaluated the association of specific phthalate metabolites with measures of allergic symptoms and sensitization in a representative sample of the U.S. population, the National Health and Nutrition Examination Survey (NHANES) 2005–2006.
Abstract and Introduction
Abstract
Background: Environmental exposures to phthalates, particularly high-molecular-weight (HMW) phthalates, are suspected to contribute to allergy.
Objective: We assessed whether phthalate metabolites are associated with allergic symptoms and sensitization in a large nationally representative sample.
Methods: We used data on urinary phthalate metabolites and allergic symptoms (hay fever, rhinitis, allergy, wheeze, asthma) and sensitization from participants ≥ 6 years of age in the National Health and Nutrition Examination Survey (NHANES) 2005–2006. Allergen sensitization was defined as a positive response to at least one of 19 specific IgE antigens (≥ 0.35 kU/L). Odds ratios (ORs) per one log10 unit change in phthalate concentration were estimated using logistic regression adjusting for age, race, body mass index, gender, creatinine, and cotinine. Separate analyses were conducted for children (6–17 years of age) and adults.
Results: The HMW phthalate metabolite monobenzyl phthalate (MBzP) was the only metabolite positively associated with current allergic symptoms in adults (wheeze, asthma, hay fever, and rhinitis). Mono-(3-carboxypropyl) phthalate and the sum of diethylhexyl phthalate metabolites (both representing HMW phthalate exposures) were positively associated with allergic sensitization in adults. Conversely, in children, HMW phthalate metabolites were inversely associated with asthma and hay fever. Of the low-molecular-weight phthalate metabolites, monoethyl phthalate was inversely associated with allergic sensitization in adults (OR = 0.79; 95% CI: 0.70, 0.90).
Conclusion: In this cross-sectional analysis of a nationally representative sample, HMW phthalate metabolites, particularly MBzP, were positively associated with allergic symptoms and sensitization in adults, but there was no strong evidence for associations between phthalates and allergy in children 6–17 years of age.
Introduction
Phthalates are common industrial chemicals used in cosmetics, personal care products, plastics, and building materials. Exposures are frequent, but the contributions of specific sources are poorly characterized. Phthalates represent a broad chemical class that includes both low-molecular-weight (LMW) compounds such as diethyl phthalate (DEP) and relatively high-molecular-weight (HMW) compounds such as diethylhexyl phthalate (DEHP) and butylbenzyl phthalate (BBzP). LMW phthalates are most commonly found in cosmetics and personal care products, whereas HMW phthalates are most associated with plastics, particularly polyvinyl chloride (PVC) building materials (Buckley et al. 2012; Carlstedt et al. 2012; Hauser and Calafat 2005). Results from dietary intervention studies suggest that food packaging is the primary source of human exposure to DEHP, but not BBzP (Koch et al. 2013; Rudel et al. 2011). BBzP exposure is associated with PVC flooring and other building materials in the home (Carlstedt et al. 2012).
Phthalates and other plasticizing chemicals have been associated with wheeze, allergies, and asthma among children (Bornehag and Nanberg 2010; Bornehag et al. 2004; Choi et al. 2010; Hsu et al. 2011; Just et al. 2012a, 2012b; Kolarik et al. 2008; Larsson et al. 2007) and adults (Jaakkola and Knight 2008; Jaakkola et al. 2006). Recent studies have measured phthalate levels in urine or dust, although earlier studies suggested a role for phthalates due to the presence of plastic materials in the home (Jaakkola and Knight 2008; Larsson et al. 2007), exposure to PVC plastics in an occupational setting (Jaakkola and Knight 2008) or use of synthetic bedding (Ponsonby et al. 2003). As the evidence for a potential role for phthalates in respiratory and allergic outcomes has increased, there is greater interest in HMW phthalates such as DEHP and BBzP, with evidence both from human and animal studies (Dearman et al. 2009; Deutschle et al. 2008; Jaakkola and Knight 2008; Koike et al. 2009; Larsen et al. 2007; Nishioka et al. 2012). These HMW phthalates alter immune responses in animal and in vitro models (Koike et al. 2009; Larsen et al. 2007). In addition, other studies suggest that DEHP and other plasticizers may act as adjuvants to enhance the allergic response (Kimber and Dearman 2010).
Recent reports have stressed the need to understand the potential allergic health effects of phthalates (Dodson et al. 2012; Hulin et al. 2012; Kwak et al. 2009). Although some evidence suggests a role of phthalates in the etiology of allergic sensitization and allergic symptoms, there is a paucity of population-based data, particularly among adults. To address this, we evaluated the association of specific phthalate metabolites with measures of allergic symptoms and sensitization in a representative sample of the U.S. population, the National Health and Nutrition Examination Survey (NHANES) 2005–2006.