Changes in Immunological and Hematological Parameters of Female Residents Exposed to Volatile Organic Compounds in the City of Kaohsiung, Taiwan

Article excerpt

Introduction

Volatile organic compounds (VOCs) are a mixture of various kinds of polycyclic aromatic, aliphatic, alicyclic, and halogenated hydrocarbons. Major constituents include benzene, toluene, xylene, styrene, naphthalene, pyrene, benzo(a)pyrene, butane, octane, hexane, and trichloroethylene. The growing number of automobiles has contributed to significant emissions of VOCs from automobile exhaust into the ambient air, especially in urban areas (Chen, Lai, & Ho, 2003; Hsieh, Chang, & Kao, 1999). Some researchers have found that the concentration of VOCs in ambient air has been highly correlated with traffic density (Bahrami, 2001).

Animal studies have confirmed a dysfunction of the immune system as a result of high VOC exposure (Robinson, Shah, Wong, & Farris, 1997; Farris, Robinson, Wong, Hahn, & Shan, 1997; Snyder & Valle, 1991; Aoyama, 1986). As for humans, some studies on benzene-induced effects have shown adverse immune functions, including alterations of serum immunoglobulins (Dimitrova, Kostadinova, Marinova, Popov, & Panev, 2005), development of antibodies (Dimitrova et al.), and decreased T-lymphocyte numbers (Moszczynsky & Lisiewicz, 1984). These studies have mainly focused on occupational exposure to workers. To date, however, there have been only a limited number of studies on biomonitoring of human populations exposed to VOCs from automobile exhaust.

Completed blood count values have been used to assess health effects from volatile pollutant exposure. In most previous studies, investigators have reported positive associations between hematological changes in workers and children and VOC exposure (Lee, Yoo, Lee, Kim, & Kim, 2002; Georgieva, Lukanova, Panev, & Popov, 1998; Shaham, Levi, Gurvich, Shain, & Ribak, 2000). However, no such association has been observed in other studies (Collins, Ireland, Easterday, Nair, & Braun, 1997). So far, most studies have emphasized the effects of VOCs on human health through occupational exposure. Furthermore, studied subjects have consisted mainly of men and children (Georgieva et al., 1998; Lee et al., 2002).

Many residents in Taiwan live adjacent to major roadways. Traffic on these primary arteries has become more congested because of the increasing number of motor vehicles in use and the volume of traffic. Policy makers and scientists have recognized the importance of assessing the potential impact of air pollutants from automobile emissions on human health. During the past decades, several investigators conducted studies on this matter; however, most studies mainly focused on the impact on respiratory and cardiovascular systems (Yang et al., 2002; Xu, Dockery, & Wan, 1991). At the time of those studies, limited data were available related to VOCs associated with immunological and hematological parameters of residents, particularly female individuals.

Overall, the aim of the study reported here was to determine whether there were any significant adverse immunological and hematological health outcomes for female residents who were environmentally exposed to VOCs from automobile emissions. Particular objectives were to 1) assess the distribution of VOCs in selected study areas, 2) measure levels of certain immunological and hematological parameters in the female population, and 3) conduct statistical analysis to determine possible association between immunological and hematological outcomes and VOC concentrations.

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Materials and Methods

Study Area

Kaohsiung, the second largest city in Taiwan, is located in the southern region of the island with an area of 153.6 [km.sup.2] and a population of 1.49 million divided into 12 districts. Sen-Ming District was chosen as the study area because of its high population density, lack of industry pollution sources, and the intersection of the Zhong-Shan freeway. This freeway was built in 1978 and is the only freeway that connects the city of Keelung (in the north of Taiwan) with Kaohsiung. …