Abstract
Fine atmospheric particulate PM2.5 (particles with diameters of <2.5>
Extracts
Particulate air pollutants have been associated with increased respiratory, cardiovascular and cancer mortality and morbidity, and with other health problems (Dockery et al., 1993; Reichhardt, 1995). The fine fraction of the atmospheric particulate matter is of great concern because it is predominantly deposited in the alveolar region of the lung where absorption efficiency is higher and the overall removal of particles is relatively inefficient (Hlavay et al., 1992; Lippmann et al., 1980). Only about 20% of particles deposited in the alveolar region are cleared in the first day, and the remaining portion is cleared very slowly (Rozman and Klassen, 1996). The fine fraction includes particles with aerodynamic diameters of <2.5>. In addition, several studies suggest an association between motorized traffic-related air pollution and diminished pulmonary function and/or increased respiratory symptoms in children (Kim et al., 2004; Weiland et al., 1994).
PM2.5 is mainly produced by particles emitted directly into the atmosphere and particles formed in the air from the chemical transformation of gaseous pollutants (secondary particles) (Kim et al., 2005). The principal types of directly emitted particles are soil related, elemental/organic carbon (EC/OC) and other particles from the combustion of fossil fuels and biomass materials. However, PM2.5 has a low level of soil particle components, and the main anthropogenic source is a product of the combustion of fossil fuels (Ohlstro¨m et al., 2000). Principal sources of PM2.5 include combustion of coal, oil, gasoline, diesel or wood, atmospheric transformation products of NOx, SO2and organic compounds, natural and anthropogenic (WHO, 2000).
It is well known that fine particles have high concentrations of many potentially toxic trace metals, such as cadmium (Cd), chromium (Cr), copper (Cu), iron (Fe), manganese (Mn), nickel (Ni), lead (Pb), vanadium (V) and zinc (Zn), that can be incorporated into the body through inhalation (Singh et al., 2002). The metal content on fine particles has been suggested as causative agents associated with adverse respiratory health effects (Dreher et al., 1997; Ghio et al., 1996). Most of the toxic metals in the air are in the form of fine particles, with a size distribution equivalent to that of aerosols (1.0 mm or less in diameter). It is suggested that these metals can produce lung tissue damage by catalyzing oxidant formation (Fang et al., 1999) and promoting the release of inflammatory mediators and cytotoxicity (Frampton et al., 1999). Recent epidemiological studies have linked low DNA repair activity with lung cancer (Paz-Elizur et al., 2003), showing that there is a component of the population with a higher cancer risk. The studies showed that this population may have a genetic predisposition to lung damage and is more susceptible to metal exposure from airborne particulates. ...
Toxicological effects of metals
Although there is no consistent evidence for the carcinogenicity of arsenic compounds in animals (WHO, 2000), there is sufficient evidence to indicate that inorganic arsenic compounds are skin and lung carcinogens in humans (WHO, 2000). Inorganic arsenic seems to affect DNA repair mechanisms (Rossman, 1981). Teratogenic effects in the hamster, rat and mouse were detected at high exposure levels (WHO, 2000). Chronic exposure to arsenic causes neurotoxic effects in human (Lagerkvist and Zetterlund, 1994). Increased mortality from cardiovascular diseases has been observed in epidemiological studies of smelter workers exposed to high levels of airborne arsenic (WHO, 2000). In addition, spontaneous abortions and lower mean birth weights have been registered in smelter workers and among subjects living in the vicinity of the smelter (WHO, 2000). …
Nickel compounds induce respiratory tract irritation, chemical pneumonia, emphysema, varying degrees of hyperplasia in pulmonary cells, and fibrosis (pneumoconiosis) in animals by inhalation (WHO, 2000). Ottolenghi et al. (1974) described a significant increase in the number of lung tumors in rats following inhalation exposure to nickel subsulfide for about two years. Nickel carbonyl inhalation in rats has produced lung tumors in one of three reported experiments compared to none in corresponding control groups (WHO, 2000). Acute inhalation exposure to nickel carbonyl has also caused lung damage, mucosal irritation, and asthma in workers exposed to inorganic nickel compounds (WHO, 2000). There is no epidemiological information on nickel uptake from the environment or relations with cancer incidence in the general population. However, nickel refinery workers exposed through inhalation to various nickel compounds have a higher risk of lung cancer and nasal cavity cancers than the non-occupationally exposed population (ICNCM, 1990; WHO, 2000). Some studies show a correlation between nickel workers and incidence of laryngeal, kidney, prostate or bone cancer (ICNCM, 1990). There is no need to emphasize the significance and need to learn more about the relevant environmental exposure concentrations of nickel, which would exert a health effect on the exposed community. …
Vanadium compounds present different toxicities which are related to the balance of the vanadium compound. The toxicity of vanadium is intermediate in the case of respiratory exposure (Vouk, 1979). Acute exposure to vanadium (tens of mg/m3) is responsible for systemic effects in animals. Damage to the liver, kidneys, gonads, haematological, cardiovascular and nervous systems have been reported (Vouk, 1979). In addition, systemic effects at very low levels of exposure have also been reported (WHO, 2000). Carter et al. (1997) showed that metals in airborne particles can induce the secretion of inflammatory cytokines in respiratory airway cells. These findings demonstrate that exposure to this metal may be associated with respiratory illness problems. Positive correlations were obtained between V concentrations in urban air and mortality from bronchitis, pneumonia, cancer and heart disease (Stocks, 1960). …
The intake for As, Ni and V were within the range of that reported by WHO (2000) - As 20- 200 ng/day, Ni 100-800 ng/day and V 1.5 µg/day. Although the levels of Ni and V were found to be relatively high in Guaynabo, they are comparable to the WHO (2000) report. However, one should consider the fact that the combined toxicity of metals is many times greater than the single metal (Shubert et al., 1978). Consequently, the need to analyze these individual constituents in ambient air is evident in order to incorporate such interactions in future epidemiological studies. ...
No comments:
Post a Comment