Analysis suggests that the cumulative effects of individual (non-carcinogenic) chemicals acting on different pathways, and a variety of related systems, organs, tissues and cells could plausibly conspire to produce carcinogenic synergies.
|Scooped by Graham Player Ph.D.|
The World Health Organization (WHO) and the International Agency for Research on Cancer (IARC) suggest that cancers due to toxic environmental exposures are between 7% and 19%. Scientists from within the chemical industry suggest the numbers are less at 5% or 10%.
The typical research done on the likelihood of chemicals to cause cancer, and the basis of these estimates, is focused on a single chemical. This is in keeping with today’s pharmaceutical and medical reductionist model where the emphasis is to find the one thing that works or the one thing that may cause disease. There is a body of literature that suggests this approach is flawed, yet it continues to be the standard.
For example, a chemical that disrupts DNA repair capacity might prove to be non-carcinogenic at any level of exposure (when tested on its own), but that very same chemical may have the potential to be an important contributor to carcinogenesis (e.g. in the presence of mutagens that cause DNA damage). Similarly, a chemical that has immuno-suppressive qualities may not be carcinogenic on its own, but if it acts to suppress the immune response, it may contribute to carcinogenesis (by dismantling an important layer of defense) in the presence of other disruptive chemicals.
Considering the multistep nature of cancer and it is clear how a series of complementary exposures to a mix of chemicals acting together might prove to be far more carcinogenic than predictions related to any single exposure might suggest.
A new report written by a team of international scientists from 28 countries reveals that low doses of chemicals considered safe on their own might cause cancer when mixed together. William Goodson III, MD, lead author of the report has suggested that we are swimming in a chemical soup and don’t know what it is doing to us.
Of the 80,000+ chemicals in use throughout the world the majority have not been tested for their effects on our health. Whether or not lifetime exposures to mixtures of non-carcinogenic chemicals in the environment (at low-dose levels) have carcinogenic potential, we don’t know. Many chemicals are known to accumulate in bodily tissues over time, but little is known about their combined effects and their impact on cancer-related mechanisms and carcinogenesis.
This latest report reviewed 85 examples of environmental chemicals and 59% of them were found to exert unanticipated low-dose effects. Clearly there is an issue here with the lifetime cumulative effects of a mix of chemicals that together influence genetic instability, chronic inflammation, and changes in cell-signaling, which all contribute to the growth of cancer. This could be the single most contributing factor to the high levels of cancer that we see today.
Here is the complete report from the study for anybody interested - http://m.carcin.oxfordjournals.org/content/36/Suppl_1/S254.full