Dr. John Budroe, a toxicologist with the Office of the Environmental Hazard Assessment in Oakland, California, said diesel exhaust has components which have been shown to damage human and animal genes and can cause cellular changes which are associated with cancer.

In a seminar held at the Asian Development Bank (ADB) in Pasig City July 9, Budroe noted a World Bank study in the early 1990s showing high levels of toxic air in major Metro Manila thoroughfares plied by diesel-fueled public transport vehicles.

The incidence of lung cancer in boys 15�19 years old is six times higher in Metro Manila than in the United States, Budroe observed, citing data from the U.S. and a study by the World Health Organization�s International Agency for Research in Cancer. The same data, he said, also showed that while there is one case of lung cancer per one million Filipino boys aged four years and younger, there is zero incidence of lung cancer in their counterpart group in the U.S.

"This is really surprising," Budroe said. "In the U.S., you just don�t see lung cancer in children because it takes time to develop a reaction to cancer causing chemicals."

Budroe, whose participation in the seminar was sponsored by the United States-Asia Environmental Partnership, cited thirty independent studies which showed that, even when the effects of smoking are excluded, workers exposed to diesel exhaust have higher risks of contracting lung cancer. He also noted that the U.S. Environmental Protection Agency concluded last year that results of studies on human subjects are "highly suggestive" that diesel exhaust causes lung cancer, Budroe told seminar participants.

The work of Dr. Budroe and his colleagues has led the California Air Resources Board to list diesel emissions as a "toxic air contaminant." As a result, a committee was formed that is now exploring ways to reduce the public health risks from diesel, through such actions as retrofitting engines, converting buses to compressed natural gas, and designing new technologies for diesel engines.

The seminar was part of efforts to eliminate smoke belching under an ADB-funded program to improve the quality of air in Metro Manila. Implementors of the program are developing an Action Plan and Memorandum of Understanding among the metropolis� local government units, jeepney and bus operators and other concerned sectors to combat air pollution in the area.

During the course of the ADB program, the Philippine Department of Health will monitor the health effects of air pollution on the public over the next five years. Earlier findings of the department showed that air pollution accounts for 22% of all respiratory diseases in Metro Manila.