I have summarised some of the main facts about the triazine herbicides. Most of the information is on atrazine with the biological effects and mode of action also applying to simazine and related triazines.
I have also added recent work that has shown that pesticides applied to land are almost certain to run off into water courses and that the importance of surface run off has been underestimated. Essentially this means that applied pesticides will pollute waterways.
TRIAZINES: IMPACTS ON HUMAN HEALTH AND WILDLIFE
Triazines are commonly used herbicides (weed-killers) primarily used in the production of maize, canola, lucerne, pyrethrum, raspberries, grapes, pasture onions, peas, potatoes, hardwood plantations(eucalypts) and softwood plantations (pines) in Tasmania.
They are some of the most common pesticide contaminants of ground, surface, and drinking water.
Atrazine can be transported as far as 1000 kilometers from the point of application and contaminant levels in rainwater can exceed its biological activity (0.1 parts per billion and even at parts per trillion) in non-target organisms. Atrazine is of concern because in addition to being widely transported and persistent (one application will be present at biologically active levels for approximately 16 months) in the environment, it is biologically active at low ecologically relevant levels. With regard to humans, atrazine has been associated with low sperm count and low fertility in men, female reproductive tract abnormalities such as polycystic ovary disease and fibroids, early onset of menses and puberty, breast cancer in those women whose well water is contaminated with atrazine, and increased prostate cancer in exposed factory workers. Recent data details the onset of leukaemia in young children with a lifetime moderate exposure to triazines.
These epidemiological studies are consistent with atrazine’s action as an endocrine disruptor, resulting in decreased testosterone levels and increased estrogen levels via the induction of aromatase (the enzyme that converts testosterone into estrogen). Other modes of action add to the complexity with the association of an increase in obesity, metabolic syndrome and diabetes. Endocrine disruptors such as atrazine are implicated in the foetal origin of adult disease. The human epidemiological data are supported by experimental work conducted in three laboratories on three continents, showing that atrazine induces aromatase and estrogen production in multiple human cancer cell lines. These data are further supported by multiple studies in laboratory rodents that demonstrate declines in testosterone and sperm production, induction of prostate disease in exposed males and the male offspring of exposed mothers, increased estrogen production and induction of mammary cancer in exposed females, and impaired mammary development in the female offspring of exposed mothers. The majority of these studies have been conducted by the US Environmental Protection Agency and the manufacturer, Syngenta (formerly Novartis). The mechanism of atrazine action is supported by studies in three species of fish, multiple species of amphibians, reptiles (turtles and alligators), and birds all showing decreased testostetone, and/or increased estrogen production (aromatase activity) and effects on sex differentiation and reproductive function consistent with this mechanism. Further, the role of atrazine-induced aromatase in breast (and likely prostate cancer) is supported by the fact that the same manufacturer (Novartis) now sells an aromatase inhibitor as a treatment for breast cancer and has suggested that it might also be used to treat prostate cancer.
In June 2009, The Endocrine Society, a highly respected international medical society of over 14,000 members in 100 countries, issued a seminal new report stating that exposures to endocrine disrupting chemicals are a growing threat to human health and well-being. The report explicitly states that “the precautionary principle is critical to enhancing health.” The paper also asserts that in order to prevent disease, “Our chemical policies at the local, state and national levels, as well as globally, need to be formulated, financed and implemented to ensure the best public health.”
This report sends a clear signal that we can no longer ignore environmental contributors to a wide range of diseases and disabilities—in fact, we need to take a precautionary approach on every level of decision-making.
There are no data to show that the triazines are actually safe, and as shown above much data to show it is un-safe and for this reason the triazines should be banned now in Tasmania.
