FAQ: Health Concerns about Pesticide Use
in Christmas Tree Production

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Should I be concerned about pesticides in my well water?

Homes next to Christmas tree productionTo 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 2006, Simazine use dropped from 72.2% of acreage to only 16.8%, and use continues to decline.

The triazines, herbicides such as Atrazine and Simazine, have been found in ground water and surface water in years past 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. In addition, EPA has information on Simazine in drinking water at Basic Information about Simazine in Drinking Water at http://water.epa.gov/drink/contaminants/basicinformation/simazine.cfm.

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.

A list of all potential drinking water contaminants and their MCL is found at Drinking Water Contaminants at http://water.epa.gov/drink/contaminants/.

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 tables list commonly used pesticides and their leaching potential:

INSECTICIDES LEACHING POTENTIALS
Asana (esfenvalerate) Very Low (PLP=2)
Dimethoate Low (PLP=47)
Di-Syston (disulfoton) Moderate (PLP=42)
Lindane Moderate (PLP=55)
Lorsban (chlorpyrifos) Low (PLP=27)
Thiodan (endosulfan) Very Low (PLP=18)

 

Herbicides LEACHING POTENTIALS
Goal (oxyfluorofen) Very Low (PLP=9)
Garlon (triclopyr) High (PLP=69)
Roundup (glyphosate) Low (PLP=23)
Simazine Moderate (PLP=54)
Stinger (clopyrallid) Moderate (PLP=53)

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.

For more information see Protecting Groundwater in NC - A Pesticide and Soil Ranking System at http://www.soil.ncsu.edu/publications/Soilfacts/AG-439-31/.

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:

Document Title (Linked to URL) URL
Your Water Supply Well Construction and Protection http://www.bae.ncsu.edu/programs/extension/publicat/wqwm/ag469.html
Protecting Water Supply Springs http://www.bae.ncsu.edu/programs/extension/publicat/wqwm/ag473-15.html

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 http://ace.orst.edu/info/extoxnet/faqs/ (click on "Pesticides" in left-hand column and then on "Pesticides in Drinking Water")
Water Quality Information
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. Some materials such as Lindane, Di-Syston and Simazine that were commonly used but are no longer widely used are also included as a convenience. The current evaluation for carcinogenicity to humans is based on a 2008 publication: Chemicals Evaluated for Carcinogenic Potential by the Office of Pesticide Programs at http://envirocancer.cornell.edu/turf/chemseval.pdf.

Ranking of Pesticides Commonly Used in WNC and Current Evaluation for Carcinogenicity to Humans

Pesticide Common Name Current Evaluation for Carcinogenicity to Humans
Dimethoate Dimethoate Possible human carcinogen
Di-Syston 15G Disulfoton Evidence of noncarcinogenicity for humans
Envidor Spirodiclofen Likely to be carcinogenic to humans
Garlon Triclopyr Not classifiable as to human carcinogenicity
Goal Oxyfluorfen Possible human carcinogen
Lindane Lindane Suggestive evidence of carcinogenicity but sufficient to assess human carcinogenic potential
Lorsban Chlorpyrifos Evidence of noncarcinogenicity for humans
Roundup Glyphosate Evidence of noncarcinogenicity for humans
Safari Dinotefuran Not likely to be carcinogenic to humans
Simazine Simazine Not likely to be carcinogenic to humans
Thionex Endosulfan Not likely to be carcinogenic to humans
Vantage Sethoxydim Not likely to be carcinogenic to humans

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.

Document Title (Linked to URL) URL
Information on Pesticides and Cancer - EXTOXNET http://ace.ace.orst.edu/info/extoxnet/tibs/carcino.htm
EPA Overview of Risk Assessment in the Pesticide Program http://www.epa.gov/pesticides/about/overview_risk_assess.htm

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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.

2005-2009 North Carolina Cancer Incidence Rates per 100,000 Population by County
Christmas Tree Counties with Highest Ranking County for Comparison
Adjusted to the 2000 US Census

Colon/Rectum Cancer: NC Average = 45.5
County Rate Rank from Highest to Lowest
Highest ranking county: Lenoir 66.7 1
Jackson 57.0 14
Mitchell 46.2 48
Alleghany 43.8 59
Watauga 41.0 75
Avery 39.1 86
Ashe
37.2 92

Lung/Bronchus Cancer: NC Average = 75.9
County Rate Rank from Highest to Lowest
Highest ranking county: Scotland 100.9 1
Avery  80.4 35
Ashe  75.4 57
Alleghany  74.9 59
Mitchell 73.8 64
Jackson  65.0 89
Watauga  54.5 98

Female Breast Cancer: NC Average = 154.5
County Rate Rank from Highest to Lowest
Highest ranking county: Camden 244.8 1
Avery 162.7 24
Watauga 155.3 36
Jackson 133.2 80
Ashe 119.2 92
Mitchell 107.8 98
Alleghany  107.3 99

Prostate Cancer: NC Average = 158.3
County Rate Rank from Highest to Lowest
Highest ranking county: Scotland 243.8 1
Alleghany 154.2 41
Jackson 153.4 44
Avery 150.9 47
Ashe 146.9 52
Mitchell 146.0 54
Watauga 143.4 57

All Cancers: NC Average = 500.1
County Rate Rank from Highest to Lowest
Highest ranking county: Lenoir 617.8 1
Jackson 507.3 37
Avery 502.5 42
Watauga 483.9 59
Ashe 475.1 68
Mitchell 461.6 75
Alleghany 437.4 87

For More Information

Document Title URL
2005-2009 Cancer Incidence Rates by County for Selected Sites per 100,000 Population Age-Adjusted to the 2000 US Census http://www.schs.state.nc.us/SCHS/CCR/incidence/2009/5yearRates.pdf/

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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.

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 Note on LD50 at http://www.rsc.org/pdf/ehsc/ld50.pdf).

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

Pesticides Oral LD50
(mg/kg)
Asana 458
Astro 998
Dimethoate 425
Floromite >5000
Lorsban 300
Provado  
Sanmite 1930
Savey >5000
Talstar >2000
Thionex 18-160
Crossbow 1000
Garlon 1847
Goal 2985
Kerb 5620
Pendulum >5000
Princep (Simazine) >5000
Roundup 5600
Stinger >5000
Vantage 2600
Table salt 3750
Aspirin 1500
Caffeine 192

Other Health Effects

The Agricultural Health Study (http://www.aghealth.nci.nih.gov/) 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 and pesticide use. The Agricultural Health Study is designed to identify occupational, lifestyle, and genetic factors that may affect the rate of diseases in farming populations.

Factsheets from the study include:

Document Title (Linked to URL) URL
PDF get PDFIncidence of Cancer http://www.aghealth.org.nci.nih.gov/pdfs/NCCancerIncidence2005.pdf
PDF Get PDFProstate Cancer http://www.aghealth.org.nci.nih.gov/pdfs/NCProstateCancer2005.pdf

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Environment FAQ's Home | Pesticides Used in Christmas Trees | Health Concerns about Pesticide Use
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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 and Jill R. Sidebottom
Email: jill_sidebottom@ncsu.edu

Updated April 2012