There are some 80,000 man-made chemicals in the industrial environment, but only a handful of them - lead, mercury manganese, acrylamide, organophosphates, heavy metals and organic solvents - have been fully tested for potential health risks.
Prof. Donald Fox (left) of Houston and Prof. Yoram Finkelstein of Jerusalem.
Photo: Judy Siegel-Itzkovich
The realization that chemicals can damage the central nervous system is not very old, so there are not many specialists with extensive knowledge of both neurology and toxicology. Eighty of these interdisciplinary experts from 16 countries, including the US, Israel, Nigeria, Japan, Estonia, Poland, Spain, Italy, the UK, India and France met last month at the Kibbutz Ma'aleh Hahamisha Guest House outside Jerusalem to discuss the latest discoveries in the field. Few of the foreign participants had ever been here.
The five-day biennial meeting of the International Neurotoxicology Association (INA) focused on Gene-Environment Interactions in Neurotoxicology and was co-chaired by Prof. Yoram Finkelstein, director of the unit of neurology & toxicology at Jerusalem's Shaare Zedek Medical Center, and by Dr. William Boyes, INA's president. The chairman of the scientific advisory committee was Prof. Donald Fox, an expert in vision science, biology, biochemistry and pharmacology at the University of Houston in Texas.
The INA, with 300 paying members - including fewer than 10 Israelis - aims to promote science and communications among countries and foster the education of medical students. It was the 12th biennial conference, and the first outside the US or Europe.
The aim of the conference was to promote greater awareness of chemicals' adverse effects on the nervous system, update experts on the latest research and provide information to regulators. Over 70 papers were delivered on subjects ranging from how children's exposure to agricultural pesticides may be responsible for the increase in attention deficit to how chronic exposure to organic solvents can lead to schizophrenia and depression. They looked at interactions between genetic inheritance and exposure to toxins, policies to reduce exposure, and how to prevent damage to health.
FINKELSTEIN has worked a great deal on the effects of chemicals on the retina and brain, especially in animals during gestation and shortly after birth. Neurotoxicology, he said in an interview, "is a combination of two very different fields, so there aren't many who specialize in it. As far as I know, I am the only physician in Israel who deals with it."
He studied neurology at Haifa's Technion-Israel Institute of Technology's Rappaport Medical School, and went on to the Weizmann Instite of Science in Rehovot to study neurochemistry. Moving to the Rambam Medical Center, he worked at its National Poison Control Center, where experts receive calls from doctors and the general public - especially parents - who fear that someone was poisoned. Finkelstein later moved to Jerusalem and joined Shaare Zedek, where he has been for two decades.
Fox, who was born in Cleveland, went to California for his postdoctoral work, and then to Texas to conduct research. Unlike other foreigners at the conference, he has visited Israel four times.
Although pulverized asbestos in the air and other pollutants can cause disease in the lungs and other organs, Fox specializes in substances from chemical and pharmaceutical industries, and chronic damage rather than acute injury. "Half of all long-term, low-level toxicity is related to the body's neurological system, because it is much more complex and has more cell types, with every part of the system susceptible, but at even lower concentrations."
Fox said 900,000 inner-city children in Washington, DC were affected by lead. The use of lead paints in the US was prohibited in 1959, so lead poisoning of US slum children from paints on furniture and peeling walls is much less common now, but low-level lead poisoning from lead water pipes, industrial air pollution and other sources "is most insidious. About 80% of learning disabilities result from levels of lead the US government say are safe."
The element, which has a sweet taste and thus is happily chewed by children, doesn't decay. "It remains in the dust, in the air, in the water - especially in poor areas. It accumulates in the bones. And children who were exposed to lead have grown up and are having children now, and they too can be affected," Fox explained.
Fox also noted that for many years, there were toys painted with or containing lead. "It doesn't kill children, but it can cause irreversible sensory, motor and cognitive deficits. Acute toxicity of a variety of chemicals can cause death, but we are mostly interested in the effects of long-term low levels."
The trigger for damage can appear in the fetus if the mother is exposed to toxic chemicals, but the effect can also appear decades later, said Finkelstein.
Harmful heavy metals are mostly found in factories, he said, but can also be found in nature. Volcanoes such as Krakatoa in Indonesia spread toxic heavy metals by air currents. Yet man-made chemicals that can damage health go back to the beginning of human history. "In the time of the pharoahs, lead was used for making ceramics, and was also put into makeup," said Finkelstein.
Toxic chemicals can cause symptoms that usually occur in chronic disease, such as parkinsonian tremors. Fox notes that there were very few cases of Parkinson's before 1817, when it was named - largely because people died at much younger ages from pre-antibiotic infections. But exposure to manganese or chemical solvents can create Parkinson-like symptoms. The condition called "Gulf War syndrome" suffered by US soldiers in Iraq was due to chemical exposure there, he continued.
The expert from Texas said he would not bar the use of very toxic chemicals but regulate them to prevent exposure to at-risk populations such as pregnant women, young children, the elderly and people with chronic disease or weak immune systems.
"Individuals with such disorders have to be supervised and treated differently when exposed to pollutants."
