Thursday, May 5, 2011

The Carcinogen Search–VAMWON Notes from the Field

VAMWON Notes from the Field are the stories of the questions I’ve encountered as a volunteer with VAMWON. The Virginia Master Well Owner Network (VAMWON) is an organization of trained volunteers and extension agents dedicated to promoting the proper construction, maintenance, and management of private water systems (wells, springs, and cisterns) in Virginia. The Cooperative Extension Services in Virginia manages the program and have numerous publications and fact sheets that can help homeowners make educated decisions about their drinking water. The VAMWON volunteer or Agent can help you identify problems with the water system and provide information on suggested treatments options and other solutions. You can find your VAMWON volunteer neighbor through this link by entering your county in the search box.

I received a homeowner inquiry from outside my region referred to me because of my quarter century as a chemical engineer working as an environmental consultant. The homeowner was trying to navigate the best way to have their water well tested and what to test it for. The homeowner was an organic farmer living within a farming community. Their property has been a working farm for over 100 years and was surrounded by other farm land. They had tested their well in the past, and it came back within the acceptable limits, but they lacked a complete list of everything that was tested for and it had been several years ago. What prompted their immediate interest was within the last month their cat and a dog were both diagnosed with cancer. Not the same type of cancer, but cancer, nonetheless. They wanted to test their water to make sure it was not the cause. Water testing is very expensive and they wanted me to help them determine what they should test for and to help them find as an affordable and appropriate testing package as possible.

Cancer is caused by changes in a cell's DNA – its genetic "blueprint". Some of these changes may be inherited from our parents, while others may be caused by exposures, which are often referred to as environmental factors. In addition, it is believed that certain environmental factors may “turn on” certain dormant viruses and other factors. Environmental factors can include a wide range of exposures, such as lifestyle factors including food and exercise, naturally occurring exposures, workplace and household exposures, and pollution.

Substances and exposures that can lead to cancer are called carcinogens. Some carcinogens do not act on DNA directly, but lead to cancer in other ways. Carcinogens do not cause cancer in every case. Substances labeled as carcinogens may have different levels of cancer-causing potential. Some may cause cancer only after prolonged, high levels of exposure. For any particular person, the risk of developing cancer depends on the person’s genetic makeup, how they are exposed to a carcinogen, the length and intensity of the exposure, and other often unknown factors. The methods of exposure are generally through skin, breathing, ingestion on food or dust (with small children and pets) and water.

There are more than 80,000 known chemicals and because there are far too many to test each one in laboratory animals, scientists use knowledge about chemical structure, information about the extent of human exposure, and other factors to select chemicals for testing. Even though it isn't possible to predict with certainty which substances will cause cancer in humans based on laboratory studies with other species alone, all known human carcinogens that have been tested in animals produce cancer in lab animals. Many carcinogens are identified not through testing, but through epidemiologic studies, which look at human populations utilizing statistics to determine which factors might be linked to cancer and often have limitations in identifying causality rather than association.

According to the International Agency for Research in Cancer, IARC, [ which is part of the World Health Organization; there are 432 substances that are today classified as known or possible carcinogens. To test the homeowner’s water for all these substances would be prohibitively expensive, but also not rational. In order to be exposed, there must be a likely source of the contamination. The water well draws from the groundwater and though it was widely believed in the past that groundwater was protected from contamination, this is not true. Obvious contamination sources, such as landfills, lagoons, and other waste facilities are easily identified. Sources not so easily recognized as potential contamination sources include agricultural, industrial, and mining operations, and naturally occurring processes such as salt water intrusion.

Gathering information from the homeowner was necessary to determine the likely sources of contamination. The homeowner was very well informed and had though about the potential source of groundwater contamination. She had focused her search on the pesticides used by her neighbors and had checked with the local distributor and farm agent to identify the most commonly used substance on the adjacent land.

Agricultural activities can cause degradation of the groundwater. Excessive use of fertilizers and pesticides or improper application or disposal of these substances can contaminate groundwater. Shallow groundwater can also be impacted by runoff of pesticides and improper well construction. Organophosphorus pesticides and herbicides were replaced in the 1930’s and 1940’s by the organochlorine chemicals that were later banned or fell out of use due to their tendency to bioaccumulate or cause long lasting damage to plants and animal life (most notably DDT, dieldrin, aldrine, and the components of Agent Orange 2,4,5 T and 2,4 D. In addition, improper management, storage and disposal of animal waste from manure piles, animal waste lagoons and feedlots (which are not common in Virginia) can contaminate groundwater with biological contaminates and nitrate. These are the direct contamination from agricultural activities.

However, other activities take place (or commonly took place) on agricultural properties. On farms it was quite common to dispose of waste by burying it, in doing so; we sometimes unwittingly contaminate ground water. Once buried, some wastes are forgotten and become more difficult to locate as time passes. Waste disposed of surface dumping in ravines also poses a threat, especially when rainwater or snowmelt seeps down through it into the groundwater. Because groundwater in many geologic formations moves slowly, a contamination problem can remain undiscovered for years or decades before the contamination plume reaches a well (or other outlet) where it is discovered. In addition in some types of geology ravines where dumping commonly took place are fissures that can run to the groundwater table.

Other sources of contamination on land with agricultural history are machinery use, fueling and maintenance. Many farms had underground fuel storage tanks that were simply abandoned over time. These abandoned tanks rust and release any residual fuel to the water and potentially to the groundwater. Farm equipment was maintained using solvents and oil. In the middle of the 20th century it was common to pour out dirty solvent and fuel on the ground or down the drain directly to the septic system and out into the groundwater. Cesspools, which directly disposed of untreated sewage wastewater into pits, are no longer permitted in Virginia, but were common in the past. Septic systems are not designed to treat pesticides, solvent and hydrocarbons and they will pass directly to the groundwater.

The homeowner in her research had determined that local farmers were using Round-Up (glyphosate), using aerial spraying extensively to keep weeds out of their fields. Glyphosate is the most widely used herbicide in the United States. Though it has long been claimed that the glyphosate broke down quickly in the environment to CO2, that has come into question and glyphosate and its similar first breakdown product appear to be far more persistent. Pure glyphosate has a low acute toxicity; however, when it is sold as a commercial herbicide it is combined with surfactants and other ingredients to make it more effective at killing weeds and potentially reaching other unintended targets. Studies show that the commercial products, such as Round Up, can be many times more toxic than pure glyphosate.

Two population studies in Sweden have linked exposure to glyphosate to Hairy Cell Leukemia and Non Hodgkin’s Lymphoma. The first study found a weak link associating non-Hodgkin’s lymphoma to recalled use of glyphosate... Another population study has found a higher incidence of Parkinson disease amongst farmers who used herbicides, including glyphosate. These are non-specific associations. Glyphosate is used with five different salts, and commercial formulations like Round-Up contain surfactants, which vary in nature and concentration. Japanese studies found acute toxicity from ingestion. More recent research suggests glyphosate induces a variety of functional abnormalities in fetuses and pregnant rats any may indicate a potential as precursors to cancer and birth defects.

The use of glyphosate containing herbicides to prevent weeds has spread rapidly after the banning of the previous organochlorine compounds including 2, 4 D and 2, 4, 5 T which together form Agent Orange and MCPA which caused persistent environmental damage. Glyphosate is a type of Organophosphorus herbicide that is believed to be far less toxic than the predecessor compounds. Our lack of true long term understanding of what these and other chemicals do to living organisms and the natural environment is stunning given the sheer volume of glyphosate used and the typical aerial application. In field studies glyphosate spray drift from aerial applications has been measured at up to 2,500 feet from the target site.

The other chemical currently in wide use amongst neighboring farms is Warrior T which is a synthetic pyrethroid, an insecticide. Natural pyrethroids are extracted from chrysanthemums. This class of insecticide is believed to be far less toxic and environmentally persistent than the organophorus and organochlorines they replaced. After discussing the cost and the studies that have been done by the homeowner decided to forgo this test.

I called a laboratory I had used in the past when doing site assessments and pricing for both Warrior T and Round-Up for the homeowner as well as identifying the WaterCheck package with pesticides that would scan her water sample for volatile organic compounds including common solvents and some of the components, additives and impurities of gasoline, historic pesticides, heavy metals, trihalomethanes, PCB and physical properties. In truth it is unlikely that the homeowner can identify a source of cancer for her pets, our knowledge of cancer is not that advanced. Also, dogs and cats in a farm environment are more likely to be exposed to pesticides and herbicides from ingestion during grooming. Nonetheless, regularly testing your own drinking water for chemicals that might be present is prudent to ensure a safe drinking water supply.

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