Christmas Tree Production and the Environment

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FAQ: Health Concerns about Pesticide Use
in Christmas Tree Production

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Should I be concerned about pesticides in my well water?

To date, the materials that have been found in well water around Christmas tree farms are Simazine; Atrazine, an herbicide similar to Simazine though not as widely used; and Lindane. Other pesticides used are not likely to get into groundwater or well water because they do not readily move down with the soil water. Of these, Simazine is the most important because it has been detected in more wells.

Simazine use continues to decline among Christmas tree growers as more growers move to weed suppression with Roundup and other materials to control weeds. From 1994 to 2000, Simazine use dropped from 72.2% of acreage to only 38.8%, and use continues to decline.

The triazines, herbicides such as Atrazine and Simazine, have been found in ground water and surface water in western North Carolina and throughout the country. The maximum contamination level (MCL) for Simazine is 4 ppb. This is the upper limit the government sets for safe drinking water. For more information of MCL's: Maximum Contamination Level (MCL) on ExToxNet FAQs http://ace.orst.edu/info/extoxnet/faqs/safedrink/mcl.htm.

For more than 10 years, high-risk wells (those close to Christmas tree farms) and public water samples have been screened for the triazines and lindane in western North Carolina.

In 351 well screenings conducted in Ashe County by the North Carolina Cooperative Extension Service from 1996 and 2000, only 5.4% of the samples had detects of triazines and none were over the MCL.

Another set of 178 water sample screenings conducted in Avery and Watauga Counties by the NCCES from 2000-2001 had 10.6% of samples with detects for the triazines, again with none over the MCL.

No water samples have been found over the MCL for lindane.

Most pesticides used in Christmas trees have a very low leaching potential - in other words, they are very unlikely to move through the soil profile into ground water. The following table lists materials commonly used and their leaching potential:

Footnote: When estimating the groundwater contamination potential (GWCP) index for a pesticide at a given site, the characteristics of the soil at the site must also be evaluated. Soil properties are as important as a pesticide's chemical properties in determining mobility and risk to groundwater.

Problem wells have been found in western North Carolina, but these have often been wells that were poorly constructed. In fact, more common contaminants of drinking water are not pesticides, but bacteria, nitrates, and lead.

For more information of proper well construction and on protecting springs:

For more information on pesticides in drinking water and water testing:

Document Title (Linked to URL)	URL
Should You Have Your Water Tested? - NC State	http://www.bae.ncsu.edu/programs/extension/publicat/ wqwm/ag473_2.html
Pesticides in drinking water EXTOXNET	http://ace.orst.edu/info/extoxnet/faqs/
PDF Pesticides in Drinking Water Wells - EPA	http://ace.orst.edu/info/npic/factsheets/drinkingwater.pdf
Simazine - EPA	http://www.epa.gov/safewater/contaminants/dw_contamfs/ simazine.html
Lindane - EPA	http://www.epa.gov/safewater/dwh/c-soc/lindane.html
Atrazine - EPA	http://www.epa.gov/safewater/dwh/c-soc/atrazine.html
Water Quality NC Cooperative Extension	http://www.ces.ncsu.edu/Publications/environment.php#water

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Do these pesticides cause cancer or other health problems?

There is considerable debate about the possible links between pesticides and cancers or other health problems. Although links between pesticides causing cancer in humans are not conclusive, reducing exposure to pesticides should be everyone's goal.

The following pesticides are commonly used by the Christmas tree industry in western North Carolina and are ranked based on the total pounds of active ingredient used. These values are based on the 2000 Pest Management Survey and survey respondents as to the rates used, number of applications per year and total acres. The current evaluation for carcinogenicity to humans is based on US EPA's July 19, 2004, "Chemicals Evaluated for Carcinogenic Potential."

Interestingly, agents and groups of agents that are known to be carcinogenic to humans include oral contraceptives, solar radiation, alcoholic beverages, and wood dust.

The following web sites provide non-biased, research-based information about the possible risks of pesticides used in the Christmas tree industry.

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Are there increased risks of getting cancer by living in areas of Christmas tree production?

The greatest concern that people have with pesticide use in Christmas trees is the risk of getting cancer. Rumors have spread through the mountains for years about cancer and Christmas tree production. One county extension agent in a mountain county tells of a woman coming into his office and telling him a Christmas tree grower bought the property next to her, and she demanded to know what kind of cancer she was now going to die from.

In reality, Christmas tree growers use far fewer pesticides than most other commodities, but many of these materials are older, and there remain concerns about cancer risk. Materials such as Lindane, Simazine, Atrazine, Dimethoate, and Goal have all been associated with cancer risks. However, the people who would be most at risk are those with the most exposure — those who are applying the pesticides. An excellent web site that explains the adverse health risks from exposure to pesticides is at the EXTOXNET site: http://ace.orst.edu/info/extoxnet/faqs/

Cancer rates in mountain counties are mostly lower than for other counties in North Carolina. The following tables show cancer rates by type for various Christmas tree producing counties compared to other counties in the state.

2000-2004 North Carolina Cancer Incidence Rates
per 100,000 Population by County
Christmas Tree Counties with Highest Ranking County for Comparison

For More Information

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Do farm workers and Christmas tree growers face health problems from pesticide use?

Although links between the use of pesticides and health problems are not clear, it should be everyone's goal to reduce exposure to pesticides. The people with the greatest exposure to pesticides are those that apply it. Worker exposure is a function of the rate being applied, the number of days per year of application and the number of years that the same kind of work is done. The longer the duration and higher the rate, the greater the risk.

Health effects of pesticides can range from acute poisonings to long-term effects from low levels of exposure. Current medical research suggests that while agricultural workers are generally healthier than the general US population, they may have higher rates of some cancers, including leukemia, myeloma, non-Hodgkin's lymphoma, and cancers of the lip, stomach, skin, brain, and prostate. Other conditions, like asthma, neurological disease, and adverse reproductive outcomes may also be related to agricultural exposures.

Acute Poisonings

Acute poisonings due to pesticide exposure depend on how toxic the pesticide is. Toxicity is often expressed as an LD50. LD stands for "Lethal Dose." LD50 is the amount of a material, given all at once, which causes the death of 50% (one-half) of a group of test animals. The LD50 is one way to measure the short-term poisoning potential (acute toxicity) of a material. The lower the value, the more toxic the material. (For more information on LD50 see http://www.ccohs.ca/oshanswers/chemicals/ld50.html).

The following is a table of the oral LD50s for commonly used pesticides on Christmas trees. Other commonly used products are shown for comparisons.

Of the materials listed, Di-Syston 15G is the most toxic. Because of concerns of worker safety, the US EPA required Christmas tree growers to develop a closed-system method of application which would not allow the worker to come onto contact with the material as it was being applied. In 2003, a worker exposure study was conducted by Avery County in cooperation with the North Carolina Cooperative Extension. This study was conducted by Dr. Ross Leidy, retired toxicologist with North Carolina State University. Five workers applied Di-Syston 15G with the new applicators for a 4-hour work period on three different days with applications of between 40 and 69 pounds being applied during that period. Samples were taken from the volunteer workers, including hand washings, face and neck swabs, air dosimeters that measure the chemical in the air during application, and pieces of clothing worn underneath disposable coveralls. Of the 135 samples taken, only 2 had any detections of disulfoton or its breakdown products above the limits of quantitation which was 50 nanograms/ml. Worker exposure was extremely low. The use of closed system applicators was required for Di-Syston starting in 2005.

Other Health Effects

The Agricultural Health Study (http://www.aghealth.org/) is an on-going study being conducted in North Carolina and Iowa of farmers and commercial pesticide applicators to document health problems associated with farming. This study explores potential causes of cancer and other diseases among farmers and their families and among commercial pesticide applicators. The Agricultural Health Study is designed to identify occupational, lifestyle, and genetic factors that may affect the rate of diseases in farming populations.

To date, the only cancer rates that have been higher among farmers and commercial pesticide applicators has been a 14% increased rate of prostate cancer.

Factsheets from the study include:

Document Title (Linked to URL)	URL
PDF Incidence of Cancer	http://www.aghealth.org/pdfs/NCCancerIncidence2005.pdf
PDF Prostate Cancer	http://www.aghealth.org/pdfs/NCProstateCancer2005.pdf

Roundup

Of special interest recently has been concern that the use of materials containing glyphosate such as Roundup increase the risk of cancer. Commonly reported on the internet is a research finding that people applying Roundup were 2.7 times more likely to get non-Hodgkin's lymphoma. Many people question Roundup's rating as evidence of non-carcinogenicity by EPA.

The original study, "A Case-Control Student of Non-Hodgkin Lymphoma and Exposure to Pesticides by Dr. Lennart Hardell and Dr. Mikael Eriksson was a case study of 442 cases on HNL in Sweden. However, in their study, only 4 people had used glyphosate and these were compared to 3 people serving as controls. The actual reported odds ratio for glyphosate is 2.3.

This article is available at the American Cancer Society web site for their scientific journal "Cancer" which is found at http://www3.interscience.wiley.com/cgi-bin/jissue/75503688.

In a paper published in American Journal of Epidemiology 2005; 162:849-857, “Occupational Exposure to Pesticides and Risk of Non-Hodgkin’s Lymphoma,” researchers L. Fritschi, G. Benke, A.M. Hughes, A. Kricker, J. Turner, C.M. Vajdic, A. Grulich, S. Milliken, J. Kaldor, and B.K. Armstrong looked for similar associations. They evaluated if exposure to different groups of pesticides (including “any pesticide”, “organophosphates”, “organochlorines”, “phenoxy herbicides”, “other herbicides” and “other pesticides”) were associated with Non-Hodgkin’s lymphoma. They viewed exposure as either “substantial” meaning more than five 8-hour days per year for a combined total of more than 5 years or “non-substantial” meaning less than that. They associated greater risks of non-Hodgkin’s lymphoma with substantial uses of all pesticide groups and little to none with non-substantial use. However, again their sample size was small with only 26 cases using a substantial amount of any pesticide.

Researchers with the Agricultural Health Study presented their findings on Roundup related cancers in 2005. Glyphosate exposure was not associated with cancer incidence overall or with most of the cancer subtypes they studied based on the 54,315 subjects included in their data set. There was a suggested association with multiple myeloma incidence that they plan to continue to monitor. Their journal article “Cancer Incidence among Glyphosate-Exposed Pesticide Applicators in the Agricultural Health Study” is available at: http://www.aghealth.org/pdfs/EHP113.49.pdf

Additional information about farmers’ exposure to Roundup can be found at Farm Family Exposure Study at http://www.farmfamilyexposure.org/index.html.

In the 2000 Pest Management Survey, Roundup was applied by Christmas tree growers in western North Carolina at lower than the labeled rates. Roundup Original is labeled at up a 10% solution or 13 ounces per gallon. Christmas tree growers in 2000 were using anywhere from to anywhere from 3 to 112 ounces of formulation per acre with an average of 20.3 ounces per acre. Current Extension recommendations are to apply Roundup at 4-8 ounces per acre to suppress and not kill weeds. This can be done without hurting the Christmas trees, even during periods of active growth. More and more growers are using this product at these low rates, applying the material 2 to 3 times per year. In 2005, mechanical application methods that did not require the use of hand application with backpack sprayers were evaluated with many of the larger growers moving to this type of application.

Recommendations for the use of agricultural chemicals are included in this publication as a convenience to the reader. The use of brand names and any mention or listing of commercial products or services in this publication does not imply endorsement by North Carolina Cooperative Extension nor discrimination against similar products or services not mentioned. Individuals who use agricultural chemicals are responsible for ensuring that the intended use complies with current regulations and conforms to the product label. Be sure to obtain current information about usage regulations and examine a current product label before applying any chemical. For assistance, contact your county Cooperative Extension agent.

Christmas Tree Production & the Environment Home | Pesticides Used in Christmas Trees | Health Concerns about Pesticide Use
Pesticide Application | Environmental Impacts | Christmas Tree Programs Home | MHCR&EC Home | NCSU | NC Cooperative Extension

Prepared by Jill Sidebottom, Ph.D.
Area Extension Forestry Specialist, Mountain Conifer IPM
NCSU College of Natural Resources
NC Cooperative Extension Service

Mountain Horticultural Crops Research & Extension Center
455 Research Drive
Mills River, NC 28759
Phone: 828.684.3562 ~ Fax: 828.684.8715
Email: jill_sidebottom@ncsu.edu

Web Crafter: Anne S. Napier ~ Email: anne_napier@ncsu.edu

Updated November 14, 2008