Martin Henry
"Aspinall's enamel surpasses all others. The finest colours in the world. Sixty years evolution in decorative art. Avoid imitations." The picture of a grave old Queen Victoria on the advertisement gives the period away. The year is 1897. And Aspinall is advertising that its enamel "is NOT made with lead and is not poisonous".
The toxicity of lead was therefore known to the paint industry from as early as 1897. But while some other countries started banning lead-based paints in houses from the 1920s, the United States did not do so until 1972. By which time an overwhelming weight of evidence had accumulated about the human damage that environmental lead does, particularly to children. Lead in the body has particularly negative effects on the nervous system. Now studies are making a link between lead in the body and violence.
PRESENCE OF LEAD
The International Centre for Environmental and Nuclear Sciences (ICENS) at the UWI, Mona, founded and headed by Professor Gerald Lalor, one of the country's most outstanding scientists, has done extensive work on the presence of lead in the Jamaican environment and on the risks posed to children. As one of their reports states: "A considerable amount of work has now been carried out in Jamaica on the occurrences and consequences of lead in the environment."
"Most of this work," the paper continues, "has concerned the lead-acid battery industry and backyard recycling from old batteries - and the effects of waste from the Old Hope mine that were dumped during the 19th century."
People started occupying the Kintyre area around the old lead mine in the 1950s with residents exposed to high levels of environmental lead for the last half-a-century. Blood lead levels have shown a significant degree of lead poisoning among children at the Kintyre Basic School. One of the corrective measures taken has been to cover the schoolyard with clean soil. Identified areas with mine wastes in the community have also been encapsulated in concrete.
It is now becoming increasingly clear that toxic effects from the environment can be passed on to future generations even when there is no direct change of the genetic material by way of mutation. These inherited changes are caused by subtle chemical influences. These environmental effects can be passed from one generation to the next by a process now referred to as 'epigenetics'. Epigenetic studies are confirming that environmental influences can indeed be inherited - even without any genetic mutations and may continue to influence the onset of diseases from generation to generation.
The field is young but is rapidly becoming well-established. Last year the U.S. National Institutes of Health granted $5 million to the Johns Hopkins Medical School to start the Center for Epigenetics of Common Human Diseases.
REDUCED FERTILITY IN RATS
And in a study published in the June 3 issue of Science magazine, Michael Skinner, who is director of the University of Washington's Center for Reproductive Biology and whose impressive CV appears on his website http://www.skinner.wsu.edu, and colleagues found that mother rats exposed to hormone-mimicking chemicals during pregnancy gave birth to four successive generations of male offspring with significantly reduced fertility. Only the first generation of mothers was exposed to a toxin, yet four generations later, the toxic effect could still be detected.
Skinner believes that his findings could explain the dramatic rise in cancers in humans in recent decades as partly due to the cumulative effects of multiple toxins over several generations. Apparently the toxins latch on to genes affecting gene functions without producing real mutations.
LEAD EXPOSURE
Lead exposure is mostly an artificial creation in the environment from human industrial activity. What about exposure to high levels of naturally occurring heavy metals? ICENS has been working with this problem for over a decade. In one of its reports on the 'Mineral Content of Indigenously Grown Foods in Jamaica', the Centre says: "There is growing concern worldwide about the effects of certain heavy metals [whether of human or natural origin] in soils and foods on human health. These concerns are increasingly reflected in the promulgation of guidelines and regulations aimed at limiting exposures to arsenic, cadmium, mercury and lead, all of which are considered potentially hazardous at low concentrations."
The unusually high concentration of a number of heavy metals in some Jamaican soils, "alarmingly high" in central Jamaica, raises concerns about their possible effects on agriculture and health, says another study focusing on yams and cadmium.
Plants grown on these soils with high concentrations of heavy metals pick up the heavy metals to varying degrees. Plants become food. Food becomes a source of intake of heavy metals for humans. So clearly there is a potential problem. One obvious approach is to use the heavy metal soil maps and the knowledge of the level to which different plants absorb different heavy metals to zone crop production.
Martin Henry is a communication specialist.
