Health and The Environment

The information is available and indisputable.

The links between individual well-being and the physical environment we all share are undeniable. All spheres of the natural world offer abundant examples of complex and not fully understood effects.

In viviparous, or "live bearing' species such as humans, gestation - the period of time in an offspring's development between fertilization and birth is a time of significant vulnerability.

While we tend to think of the developing organism as relatively well-shielded prior to birth, in fact its not always the case. The mother-fetus unit has always been exposed to a variety of harmful stimuli. And no doubt there have been adaptations throughout evolution; perhaps the majority of those responses have been protective. However, as human societies become increasingly populous and complex, by-products of such change can create new exposures. Science, and medicine in particular, is now observing and measuring some of the human impacts.

The article Childhood Cancers and Atmospheric Carcinogens, by E G Knox, recently appeared in The Journal of Epidemiology and Public Health, part of the British Medical Journal Group.

Its thesis: Most childhood cancers are the result of prenatal exposure to industrial and environmental pollutants inhaled by the mother during pregnancy.

Commentary

From the articles abstract:

Aim: To retest previous findings that childhood cancers are probably initiated by prenatal exposures to combustion process gases and to volatile organic compounds (VOCs); and to identify specific chemical hazards.

Design: Birth and death addresses of fatal child cancers in Great Britain between 1966 and 1980, were linked with high local atmospheric emissions of different chemical species. Among migrant [Note: those who moved] children, distances from each address to the nearest emissions "hotspot" were compared.

Setting and subjects: Maps of emissions of many different substances published on the internet by the National Atmospheric Emissions Inventory and "hotspots" for 2001 were examined. Child cancer addresses were determined from previous databases.

Conclusions: Reported associations of cancer birth places with sites of industrial combustion, VOCs uses, and associated engine exhausts, are confirmed. Newly identified specific hazards include known carcinogens. The mother probably inhales these or related materials and passes them to the fetus across the placenta.

[Note: placenta is the special tissue that joins the mother to her fetus; it provides the fetus with oxygen, water, and nutrients (food) from the mother's blood and secretes the hormones necessary for successful pregnancy. From the National Institutes of Health. Note that there is no mention of unwanted substances passing across the placental barrier in this definition.]

Additional observations from the original article:

These hazards, non-methane volatile organic compounds, variously reflect solvent use, engine exhaust, fuel evaporation, and other industrial/refinery processes.

Childhood cancer/leukemia births are closely associated with high atmospheric emissions from combustion processes, mainly oil based, and from organic evaporation.

When all the data had been compiled and the risks were calculated, children born within a 1 km radius of emissions hotspots of particular chemicals were between two and four times as likely to die of cancer before reaching the age of 16, as other children.

Dr. George Knox, professor emeritus at the University of Birmingham said that the children were probably exposed to common carcinogens inhaled by their mothers while they were in the womb. "Most childhood cancers are probably initiated by close prenatal encounters with one or more of these high emissions sources."

This very brief summary does not do justice to the information in Dr. Knox's article. Please read it in its entirety. http://jech.bmjjournals.com/cgi/content/full/59/2/101