Research Article Open Access Ballester F et al., J Pollut Eff Cont 2014, 2:2 DOI: 10.4172/2375-4397.1000114 Review Article Open Access Volume 2 • Issue 2 • 1000114 J Pollut Eff Cont ISSN:2375-4397 JPE, an open access journal Keywords: Air pollution; Benzene; Respiratory health problems; Children; Adolescents Introduction Seven million premature deaths in the year 2012 could be attributable to air pollution, according to the World Health Organization (WHO) in its last Burden of Disease report [1]. Around 4.3 out of 7 million were caused by ambient air pollution and 3.7 million by household air pollution. In recent years, evidence regarding air pollution efects on the child respiratory system are growing considerably and they are observable at normal levels [2,3]. An impairment of respiratory health during childhood has been related with both indoor [4,5] and outdoor [6,7] air pollution. Respiratory diseases are among the main causes of child morbidity and mortality. Currently, pneumonia along with diarrhea is the major cause of death in children under fve years old [8]. Moreover, because of their physiologic and behavioral features, children are more exposed to air pollutants than adults and their vulnerability to respiratory illnesses is also higher [6,8-10]. Consequently, studies conducted to broaden knowledge about risk factors for respiratory child health are relevant. Benzene, which is a volatile organic compound (VOC), is a constituent of petroleum and a well-known solvent. Terefore, trafc vehicles, gas station emissions, some industries, tobacco smoke, and some cleaning products are the main emission sources of this pollutant [11]. Te potential of carcinogenic and immunologic efects afer chronic exposure is well known [11-13]. Furthermore, chronic benzene exposure has also been related to respiratory problems, such as asthma and lung infections in children [14,15] and/or adults [16,17]. A wide variety of reference levels for benzene exposure exists worldwide. In the US, the Integrated Risk Information System (IRIS) of the Environmental Protection Agency (EPA) established 30 μg/m 3 as reference concentration for inhalation (RfC) [18]. In addition, the Agency for Toxic Substances and Disease Registry (ATSDR) proposed as the minimal risk level (MRL) for benzene inhalation the levels of 0.009 ppm (2.8 μg/m 3 ) and 0.006 ppm (1.9 μg/m 3 ) for an acute and intermediate term exposure, respectively. In occupational exposure, the National Institute for Occupational Safety and Health (NIOSH, [19]) also established 0,1 ppm (31.3 μg/m 3 ) as recommended exposure limits (REL) for a 10-hour exposure to benzene. More recently, a European regulation established an annual boundary value in ambient air for benzene ensuring human health of 5 μg/m 3 (CE 50/2008 [20]). However, due to the sufcient evidences for categorizing benzene as a carcinogen, WHO has not considered any threshold level devoid of risks for exposure to this compound [13]. A level of 1.7 μg/m 3 is considered by this organization as a guideline not to be exceeded since it has been associated with an increase of 1/100000 in the lifetime risk of sufering cancer [21]. Summaries of the scientifc knowledge could help to update the state-of-the-art and to address preventive and regulatory measures. Previously, other reviews have already summarized indoor and outdoor exposure to air pollutants in relation with respiratory health in children and adults, including a general section for VOCs within the pollutants assessed [4,15,22]. However, to the best of our knowledge, no review studies have been carried out to summarize the relationship between benzene exposure and respiratory health in child populations. Te aim of this review is to summarize the epidemiological studies on the relationship between air exposure to benzene, directly measured, and respiratory problems among children. *Corresponding author: Ferran Ballester, Environment and Health Area, Foundation for the Promotion of Health and Biomedical Research in the Valencian Region, FISABIO –Public Health, Valencia, Spain, Tel: +34 961 92 57 79; E-mail: ballester_fer@gva.es Received July 18, 2014; Accepted August 11, 2014; Published August 22, 2014 Citation: Ferrero A, Íñiguez C, Esplugues A, Estarlich M, Ballester F (2014) Benzene Exposure and Respiratory Health in Children: A Systematic Review of Epidemiologic Evidences. J Pollut Eff Cont 2: 114 doi: 10.4172/2375-4397.1000114 Copyright: © 2014 Ballester F, et al. This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited. Abstract The aim of this review is to summarize epidemiological studies on the relationship between air exposure to benzene and respiratory health among children and adolescents. To the best of our knowledge, no previous review on this topic has been published. An exhaustive search in on-line bibliographic databases (PubMed and Web of Science) was carried out in April 2014. We selected observational analytical studies with individual data analyzing outdoor, indoor and personal exposure to benzene, and their association with at least one respiratory health outcome in children aged up to 18 years old. Fourteen papers published between 1999 and 2014 were selected (fve for indoor, six for outdoor and three for personal exposure). In general, benzene exposure levels found in the studies were low, ranging between 1.5 and 24.8 μg/m 3 . Indoor exposure was higher than outdoor and personal exposure. Overall fndings suggest that an increase in benzene exposure could impair respiratory health (asthma, lung function and pulmonary infections) in children aged up to 18 years old. However, since great diversity in methods and study designs exist, comparisons between results are hampered. Further research is needed to broaden knowledge on the effects of benzene on respiratory health during childhood. Benzene Exposure and Respiratory Health in Children: A Systematic Review of Epidemiologic Evidences Amparo Ferrero 1,2 , Carmen Íñiguez 1,2,3 , Ana Esplugues 2,3 , Marisa Estarlich 1,2,3 and Ferran Ballester *1,2,3 1 Foundation for the Promotion of Health and Biomedical Research in the Valencian Region, FISABIO –Public Health, Valencia, Spain 2 Spanish Consortium for Research on Epidemiology and Public Health (CIBERESP), Madrid, Spain 3 Faculty of Nursing, University of Valencia, Valencia, Spain Journal of Pollution Effects & Control J o u r n a l o f P o l l u t i o n E f f e c t s & C o n t r o l ISSN: 2375-4397