Volatile Organic Compounds in Air: Sources, Distribution, Exposure and Associated Illnesses in Children

Abstract

Background: Toxic volatile organic compounds (VOC), like benzene, toluene, ethylbenzene and xylenes (BTEX), are atmospheric pollutants representing a threat to human health. They are released into the environment from mobile sources in urban settings, but newly polluted areas are gaining importance in countries where accelerated industrialization is taking place in suburban or rural settings.

Methods: The review includes studies done in Mexico and Latin-America and countries considered to have emerging economies and are compared with similar studies in developed countries. Data about environmental VOC levels and exposure of children have been included. Also, information about health effects was reviewed. Articles were searched in PubMed and Scopus, and information was also obtained from the United States Environmental Protection Agency (EPA), the EPAs Integrated Risk Information System (IRIS-EPA) and state reports on air quality of Mexican cities.

Results: VOC or BTEX levels reported in industrial and suburban areas were found to be higher due to the burning of fossil fuels and waste emission; whereas, in big cities, VOC emissions were mainly due to mobile sources. Even though TEX levels were under reference values, benzene was found at levels several times over this value in cities and even higher in industrial zones. Elevated VOC emissions were also reported in cities with industrial development in their peripheral rural areas.Public health relevance: Industrial activities have changed the way of life of small towns, which previously had no concern about environmental pollution and chemicals. No air monitoring is done in these places where toxic chemicals are released into rivers and the atmosphere. This work demonstrates the need for environmental monitors to protect human life in suburban and rural areas where industrial growth occurs without planning and ecological or health protection, compromising the health of new generations beginning in fetal development.

Figure 1

Highest levels of benzene reported in urban and industrial areas, both in developed and developing countries. Notice the extraordinary low levels reported in urban Canada (left panel) and industrial Sweden (right panel). Industrial areas in Latin America are not continuously monitored for air quality, only great cities, but children and pregnant women live in these places where pollution is generally high. Urb-urban; pers-personal; PCh-petrochemical zone; Ind-industrial zone; PollRiv-polluted river.

Figure 2

Chemical structure of BTEX. Upper line: benzene, toluene and ethylbenzene. Lower line: orto-, meta- and para-xylene.

Figure 3

Probable pathways of benzene leukemogenic activity. These events might take place either in the fetal liver or in the infant bone marrow, or in both, to produce childhood leukemia (based on [1056]).

Figure 4

Oxidative stress, gene regulation and cytotoxic effects due to exposure to BTEX. ROS-reactive oxygen species; FR-free radicals. Prx – peroxiredoxin; Trx – thioredoxin; GPXs – glutathione peroxidase.