Timing of toxic exposures crucial to disease

Comment: Since Virginia is under threat of uranium mining, remember the processing of uranium from open pit mining to milling will ruin our water with heavy metals!

By Tessa Salazar
Philippine Daily Inquirer
First Posted 00:04:00 08/15/2009

DURING their early age, humans are most vulnerable to even small amounts of environmental toxins. What’s more troubling is that some of the effects of these exposures may only be seen or felt much later on in life.

This was the observation of Dr. Irma Makalinao, pharmacy and toxicology specialist and professor at the College of Medicine of the University of the Philippines, during a recent Philippine College of Physicians health forum.

One example Makalinao cited was children’s exposure to the heavy metal lead. Lead, in small amounts, affects a child’s nervous system and intellectual development. Recently, imported toys mostly made from China have been tested to contain lead.

“A child with otherwise normal physical and structural attributes could have his or her IQ (intelligence quotient) impaired because of lead exposure,” Makalinao said.

Other diseases that may be linked to environmental exposures of “fetal origin” include Parkinson’s disease, cancer, hypertension and heart disease.

Makalinao, a toxicologist and a pediatrician who advocates environmental health, said part of her job would be to investigate cases of exposures to lead, mercury and other toxic substances.

Certain toxic exposures, she noted, “could lead to an early manifestation of the gene for Parkinson’s disease since there’s a gene-environment interaction for a disease like Parkinson’s.”

Mad cow disease

BSE (bovine spongiform encephalopathy), more commonly known as mad cow disease, is a debilitating nervous system condition in cows that affects the animal’s behavior and movements. A cow infected with BSE would seem to act “mad.”

Dr. Richard Lacey, a prominent microbiologist and BSE researcher, has said there is an overwhelming scientific and medical case for avoiding the consumption of meat and meat products just to avoid BSE being transmitted to humans.

The connection between BSE and humans was uncovered in Great Britain in the 1990s when several youngsters died of a brain disorder, which was discovered to be a variation of a rare brain disorder called Creutzfeldt-Jakob Disease (CJD), which typically strikes elderly people.

Dr. Jaime Montoya, in an interview with Inquirer Science/Health, explained that CJD “is a progressive deterioration of mental status of patient who may have ingested infected brain from cattle and other livestock. BSE has been implicated in the use of ground beef and infected cow parts as part of cattle feed.”

However, Montoya added that no data were yet available for the incidence of CJD and BSE in the Philippines.

Disturbing occurrence

During the PCP forum, Makalinao explained that another disturbing occurrence happens whenever meat is grilled.

“When we burn meat, what is generated are polyaromatic hydrocarbons (polycyclic aromatic hydrocarbons).” These PAHs, she explained, are linked to the development of cancer in humans.

“From the perspective of pharmacogenetics, there is what we call the gene-environment interaction as well. If a person having a particular gene (that carries a certain susceptibility to a type of cancer) becomes exposed to a trigger, the risk for developing cancer is higher so that sometimes even if the exposure is not repeated several times, then the possibility of developing that type of cancer would actually be more likely than another person who does not carry the gene.”

Makalinao added that part of the studies being conducted by the UP Institute of Human Genetics is “to find cancer susceptibility genes particularly in relation to smoking and some other factors so that we can actually advise people more adequately about this issue on the development of cancer.”

Dr. Eva Maria Cutiongco-de la Paz, assistant director, Institute of Human Genetics, National Institute of Health, UP Manila, confirmed to Inquirer Health this week that the institute has projects on identifying one’s gene variation that increases risk for a particular disease as well as environmental risks (such as potential carcinogens).

She also stressed the importance of ethnic variations tests specific for Filipinos who needed to know their risks and how they can help themselves avoid these risks.

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