DOCUMENTATION: by Associate Professor Ray KearneyNews Weekly
Ethanol benefits become important public health issue
, May 3, 2003
Around the world, governments are taking strong measures to reduce air pollution from motor vehicles. Associate Professor Ray Kearney, Department of Infectious Diseases and Immunology at the University of Sydney, explains why ethanol in fuel is becoming an important public health issue.Particulate matter (PM) in air is a complex mixture of suspended particles that vary in size and chemical composition. Over the past decade, many epidemiologic studies have shown a positive association between exposure to small, short-term increases in PM levels (e.g., a.m. and p.m. peak traffic periods) and increases in illnesses such as worsening symptoms of asthma and daily mortality e.g., heart disease.
Long-term exposure is documented to have an association with respiratory and cardiovascular disease as well as a fifth of lung cancer cases. Widespread exposure to vehicular pollutants significantly affects public health.Vehicle emissions
The sources of PM are numerous but in an urban environment, particles arise mainly as a result of fuel combustion from motor vehicles.
A significant fraction of PM, referred to as ‘secondary particles' form when the combustion gas condenses at cooler temperatures or reacts with other chemicals in the atmosphere e.g., ozone to form nitrates, sulphates and other particles.
Thus the PM is a complex mixture of solid and liquid particles varying in size, composition and concentration. Exhaust particles can range in size from approximately 0.005 to 100µm in aerodynamic diameter. Three main modes of article sizes include nuclei mode or ultra-fine (less than 0.1µm), accumulation mode or fine (0.1 - 1µm) and coarse mode (greater than 1µm).
The fine and ultra-fine PM are largely soluble, respirable and contain the bulk of the carcinogenic components categorized as polycyclicaromatic hydrocarbons (PAH's). The bulk of the coarse particles are insoluble and are generated by mechanical processes e.g., wear and tear of tyres and includes resuspended dust from road surfaces.
Whilst the coarse particles form the highest proportion of mass of PM, the ultra-fines represent only 1 – 8% of this mass.
Ultra-fines are present in greatest numbers and in a fixed volume have far greater total surface area than coarse particles. Thus fine and ultra-fine particles have the capacity to deliver a significantly greater toxic load that is soluble when inhaled deep into the air-exchange units or alveoli of the lung.
In general, the coarse particles consist mainly of insoluble crust-derived minerals and biological material such as pollen and bacteria. In contrast, fine articles contain a variety of toxic metals, irritants and carcinogens.
Particulate pollutants, when inhaled, encounter many different kinds of lung defences. The first barriers contain sticky surfaces on which ciliated cells propel the mucous upwards.
Larger articles can be removed by coughing when irritating particles activate nerve cells in the airways. Deeper in the lungs, the fine particles can reach the alveoli and be removed by scavenger cells such as macrophages and neutrophils (white cells in blood and tissue). Removal of the fine particles from the alveoli is by cellular transport or absorption of the solubilised fine particles.
An average adult breathes about 16 cubic metres of air per 24 hours. Approximately 43% of the inhaled particulates are retained either in the lung or absorbed into the body.
Calculations show that counts around 5000 particles/cm3
(clean air) and a deposition of 43%, someone breathing normally would retain 40 x 1010
ultra-fine particles per 24 hours. Given even distribution, which of course does not occur in people with lung disease, this implies a dose of 1350 articles to each of their 296 million alveoli.
The human lung (five lobes) has an internal surface area equivalent to that of two tennis courts and provides a formidably large surface area for transport of adsorbed toxic substances to the alveolar membrane and, therefore, the potential for toxic effects.
Recent research has established that exhaust particles increase the receptors on lung cells for cell-wall components (endotoxin) of certain bacteria. The effect is to cause the lung to be super-sensitive to low concentrations of endotoxin to produce severe pulmonary inflammation.
Such inflammation in at-risk persons, such as bronchitics and asthmatics, can rovoke severe episodes of illness.
Equally significant is the recent finding that exposure to exhaust PM causes elevation of C-reactive protein (CRP) and fibrinogen from the liver triggered by mediators of lung inflammation.
Both CRP and fibrinogen promote platelet aggregation and clot formation with risks of multiple effects throughout the cardiovascular system, including enhanced blood clotting.
The authors also demonstrated a decrease in red blood cell (RBC) count upon exposure to exhaust pollution. Evidence indicated that the RBC's became adhered to the walls of pulmonary blood vessels rendered ‘sticky' by inflammatory mediators generated in the lung tissue by inhaled irritants.
Thus article deposition can set off a cascade of events in many cells both locally and distally. Such reactions may be temporary and reversible but daily exposure, especially during morning and afternoon peak hours can produce cumulative effects with risk of serious tissue injury, including the development of cancers.
It is well documented that the most potent accelerator of cancer growth is inflammation, either locally or distally. Thus the presence of chronic pulmonary inflammatory disorders, exacerbated by exposure to pollutants that are known to contain carcinogens, can be a risk factor for tumours, not only in the lung, but elsewhere exposed to absorbed carcinogens form fine particulates. See accompanying photo that illustrates experimentally how inflammation induced by bacterial endotoxin or lipopolysaccharide (LPS) can greatly accelerate the establishment and growth of tumour cells
Such findings present a credible view of how even low-level exposure to PM may alter cardiovascular and pulmonary systems and pose a particular threat to persons already with such conditions.
On the basis of this evidence, government agencies around the world are taking action to reduce particle emissions from fossil fuels, especially from motor vehicles. progress in this direction will be enhanced by introducing alcohol into fossil fuels. This is not new but today it requires the public to be educated in an open and honest manner.
Like the tobacco industry, the petroleum cartels also are extremely protective of their products and purposely ignore the proven health risks of their products. Such unconscionable conduct must now be addressed in the light of compelling evidence of proven adverse health impacts attributed to fumes of combusted fossil fuels
In Australia recently, a concerted campaign seems to be underway by petroleum interests to change the thinking of the public by classical propaganda techniques. In articular, the issue of ethanol has been associated with negative symbols such as ‘engine damage' and ‘invalidation of car warranties' in the hope that the public will reject ethanol without the full evidence being presented to an unsuspecting public.
Ethanol is a proven clean energy source that is renewable. It can provide an immense boost to the sugar-cane industry and restore viability in the face of international economic trade barriers. Equally important is that the percentage of ethanol added to fuel will logically reduce the health impact proportionately.
Car manufacturers overseas such as Ford, Chrysler and Mazda are now producing motor vehicles that can be automatically computated to run efficiently on alcohol fuel with blends as high as 85% ethanol.
What is needed is a Federal Government with the will and wisdom to implement such a change with a win-win outcome for the public, producers and business stakeholders as well as the environment.