CEM India - Abstract

Abstract Information :

Among the Volatile organic compounds, Benzene demands special attention. The US EPA risk assessment guidelines of 1986 had classified benzene as a “known human carcinogen” (Category A). The current carcinogenic risk assessment guidelines given by US EPA in 2005 has characterized benzene as a known human carcinogen based on human exposure evidence along with other supporting evidence from animal studies. Occupational based human exposure studies have concluded that exposure to benzene leads to toxic effects, both by oral and inhalation exposure. Considering the toxic profile and the ubiquitous nature, it is necessary to monitor and regulate benzene in the ambient air. Between January 2018-May 2018 an extensive literature review was conducted for ambient air quality standards of benzene from official documents, published literature and official websites of 193 WHO member states. These were cross-verified and confirmed with environmental performance reports published by the World Bank, The United States Environmental Protection Agency (US EPA), Clean Air Asia documents, Air quality catalog from United Nations Environment Programme (UNEP). According to ‘Human Health Evaluation Manual, Supplemental Guidance: Update of Standard Default Exposure Factors’, risk assessment was carried for all the permissible benzene standard values prescribed by different national legislation. As per the ‘Recommended Default Exposure Factors’ (2014), the average weight of the person was considered as 80 kg, outdoor exposure frequency as 225 days/year, lifetime as 70 years and air inhalation rate as 20 m3 /day. By considering all the above factors Chronic Daily Intake (CDI) was determined. Potency factor of 2.9 x 10-2 was used to determine the lifetime incremental cancer risk. As expected, the permissible values are not equally protective. If one in 100 thousand is taken as an acceptable risk, values higher than 5 µg/m3 cannot be set as standard. Alternatively, if a higher level of protection, characterized by 1 in a million permissible risk is required, even the most stringent standard is insufficient. Among the 193 countries, only 53 (≈ 27%) have a standard for benzene even when it is a chemical of concern and studies have shown its presence in the indoor and outdoor air throughout the world. The standards prescribed by legislations vary in more than one order of magnitude. Even adjoining countries have standards that are quite different. As air pollution does not respect political boundaries, such differences in standards will make the regulations meaningless. In addition to this, the available standards are not protective of human health. Since air pollution is a global issue there is an urgent need to harmonize the standards worldwide. Such a move will improve the air quality locally, nationally and globally. Along with that the governments should come forward to enact stricter clean air legislation and should carry out regular air quality monitoring.