From: Dr. Diana Post, Rachel Carson Council
Date: January 2011
5 Pesticide Active Ingredients - Caution Needed
Information on Pesticides for Master Gardeners Requires Greater Emphasis on Potential Hazards
Introduction
In 2010, we became aware that five pesticide active ingredients (for use on turf) had been presented at a Master Gardener training session and described variously as “new, novel, or safe.” To our knowledge, information given at the training session did not fully disclose potential hazards associated with the five chemicals. In response to this we have assembled the following information about these five active ingredients. We sent this information to those running the training session and are providing the information to the public as well.
For products new to the market it is especially important that all known potential hazards be clearly identified to users. For example the dangers to aquatic invertebrates associate with three of five chemicals were not pointed out to the Master Gardeners.
The likelihood of adverse effects from pesticides depends on the care with which the public uses them. If the public believes them to be safe, they may fail to read or follow the product label’s directions, restrictions, warnings, or cautions, etc.
Users need to study pesticide labels carefully for any and all hazards indicated. Such labels are considered legal documents and users are required to follow them.
We believe that there are questions that the public should be asking of those who are in charge of Master Gardener programs. Including:
Does promoting of five pesticides to Master Gardeners in a training session without full disclosure of their potential toxicities indicate a problem?
Should Master Gardeners who are responsible for giving information to the public about pest control including use of chemical pesticides be certified in pesticide information and rudimentary toxicology?
The information below is presented first grouped by hazard, than as individual active ingredients.
Active Ingredients’ Hazards
Toxicity to Invertebrates
Three insecticidal chemicals - chlorantraniliprole, indoxacarb, and pyriproxyfen (based on tests submitted to EPA) were determined to present high to very high toxicity for aquatic invertebrates (see below for details). This is important since pesticide runoff into surface water from residential and other turf sites could lead to population reductions of these critical organisms. Invertebrate organisms are at the base of most aquatic food chains.
Toxicity to Mammals
Three of the five chemicals produced health-related problems in laboratory mammals as follows:
Indoxacarb was found more toxic for females than for males and was found to produce signs of neurotoxicity, weakness, head tilting, abnormal gait or mobility with inability to stand.
Pyriproxyfen was found to cause pathological changes in the mammalian liver, and blood. “Individuals with preexisting diseases of the liver, kidney, red blood cell or central nervous system may have increased susceptibility to the toxicity of excess exposure [to pyriproxyfen].” (MSDS for Esteem Ant Bait)
Mesotrione was found to produce increased plasma tyrosine levels with related ocular, liver and kidney effects. There is some concern about the effects of increased tyrosine levels on the developing nervous system of children. Newborns can be tested for tyrosine levels to rule out a genetic disorder.
Groundwater Leaching Potential
Two out of the five chemicals, chlorantraniliprole and aminocyclopyrachlor were determined to have the potential to reach groundwater. This is important since nearly half of our drinking water comes from wells. Contamination is expensive to detect, even more expensive to remove and can be hazardous to human and animal health. So, prevention of leaching by not registering pesticides that can migrate to groundwater is the best way to avoid it. Next best is to make certain that users are aware of such a possibility when the chemicals are applied.
Toxicity to Bees
Two of the five chemicals were found toxic to bees: indoxacarb by the contact route is highly toxic and pyriproxyfen is moderately toxic.
Estrogenic Action
One of the five chemicals, pyriproxyfen was determined to be estrogenic.
Persistence of Herbicide Activity in Compost
One, of the five chemicals, the herbicide aminocyclopyrachlor can remain active in treated plant material used for compost or mulch. Presumably, plant roots can take up aminocyclopyrachlor from treated soil. A serious Restriction referring to systemic activity and persistence appears on an aminocyclopyrachlor-containing product label as follows: “Do not use grass clippings from treated areas for mulching or compost, or allow for collection to composting facilities. Grass clippings must either be left on the treated area, or, if allowed by local yard waste regulations, disposed of in the trash. Applicators must give verbal or written notice to property owner/property manager/residents to not use grass clippings from treated turf for mulch or compost.” (label for Imprelis). This information appears at the end of the label in a list with a number of other Restrictions and easily could be overlooked by a user who believed the product to be safe.
Individual Chemical’s Toxic Effects
Insecticides: None were carcinogens,
Chlorantraniliprole: CAS# 500008-45-7
Action: This is a selective ryanodine receptor agonist, The ryanodine receptor in cells and muscle tissue mediates the release of calcium an essential step in muscle contraction. Chlorantraniliprole has been found active against butterflies, moths and beetles. It has been effective in conjunction with beneficial nematodes for control of grubs in turf. Note: This chemical was promoted to Master Gardeners as having “unsurpassed control of grubs.” However, a researcher from Rutgers found that A combination of chlorantraniliprole and the nematode, H. bacteriophora offered a “highly IPM compatible alternative for remedial white grub control… [and] Significant control… was observed in [only] 12% of the chlorantraniliprole alone treatments…” (Koppenhofer, A., & E. Fuzy, “Effect of the anthranilic diamide insecticide, chlorantraniliprole, on Heterorhabditis bacteriophora (Rhabditida: Heterorhabditidae) efficacy against white grubs (Coleoptera: Scarabaeidae,” Biological Control, 45(2008) 93-102)
Persistence: It has been found persistent in aquatic and terrestrial environments (in the latter case lasting for up to 3 years).
“This chemical has properties and characteristics associated with chemicals detected in ground water. The use of this chemical in areas where soils are permeable, particularly where the water table is shallow, may result in ground-water contamination. (EPA Fact Sheet- April 2008 for chlorantraniliprole)
Toxicity to Non-Targets: Chlorantraniliprole is not considered toxic to terrestrial mammals, birds and bees. However, it presents a potential hazard to certain terrestrial insects. It is slightly toxic to fish. “This pesticide is toxic to aquatic invertebrates, oysters and shrimp.” [In order to reduce aquatic hazards from C. the label includes advice on preventing runoff from treated areas (EPA Fact Sheet- April 2008 for chlorantraniliprole)
A Surface Water Advisory is required for product labeling.
Indoxacarb: CAS# 173584-44-6
Action: It is a nerve toxin and blocks the voltage-dependant sodium channels in nerves. (note: DDT and pyrethroids cause leakage of the sodium channels).
In October 30, 2000 Indoxacarb was given conditional registration. The condition was that more data on degradation by-products be received by EPA. This insecticide was designated a “reduced risk” pesticide and is considered an organophosphate (OP) replacement.”
This chemical belongs to the oxadiazine chemical family and is registered for the control of lepidopterous (butterflies and moths) pests in the larval stages.
Ground water: no evidence of migration to groundwater
Persistence: aerobic half lives of 3-693 days, anaerobic half lives from 147 - 233 days (EPA Fact Sheet, 10-30-00)
Toxicity: It is considered moderately toxic to mammals (EPA Toxicity Category ll) and more toxic for females than for males. Neurotoxicity was observed in lab animals: “weakness, head tilting, abnormal gait or mobility with inability to stand.” (EPA Fact Sheet, 10-30-00)
Environmental Hazards: “This pesticide is toxic to mammals, birds, fish and aquatic invertebrates. Do not apply directly to water or to areas where surface water is present or to intertidal areas below the mean high water mark. Runoff from treated areas may be hazardous to aquatic organisms in neighboring areas.”(Page 3-EPA Fact Sheet 10-30-00)
Bees: “Risks to bees via the dietary route were considered minimal; however, high toxicities were noted by the contact routes.” (EPA Fact Sheet, 10-30-00)
Source of data- “EPA Pesticide Fact Sheet for Indoxacarb Conditional Registration October 30, 2000.”
“Due to the exceptionally complex degradation scheme [of indoxacarb], the registration is conditional upon receiving further elucidation and characterization of some additional degradates.” (EPA Fact Sheet, 10-30-00)
Pyriproxyfen: CAS# 95737-68-1
Action: It is a juvenile hormone analog used for control of house flies, mosquitoes, fire ants, as well as certain types of aphid, scale, whitefly and psylla insects.
Technical chemical toxicity: Mammalian: can cause pathological changes in the mammalian liver. “On long-term or repeated exposure: The substance may have effects on the blood and liver, resulting in anemia, impaired functions and tissue lesions.” (International Chemical Safety Cards-NIOSH for pyriproxyfen) “Individuals with preexisting diseases of the liver, kidney, red blood cell or central nervous system may have increased susceptibility to the toxicity of excessive exposures.”(MSDS Sheet for Esteem Ant Bait)
Environmental Toxicity of technical pyriproxyfen
It is moderately toxic to bird species, honeybees, and aquatic plants (PPDB-Footprint) “Pyriproxyfen Technical is moderately to highly toxic to fish and moderately to very highly toxic to aquatic invertebrate species.” ((MSDS for ESTEEM Ant Bait) “The substance [pyriproxyfen] is very toxic to aquatic organisms. In the food chain important to humans, bioaccumulation takes place, specifically in aquatic organisms. The substance may cause long-term effects in the aquatic environment. Avoid release to the environment in circumstances different to [sic] normal use.” (International Chemical Safety Cards-NIOSH for pyriproxyfen)
It has been found to have estrogenic activity in laboratory tests (Kojima, M. et al “Evaluation of estrogenic activities of pesticides using an in vitro reporter gene assay” Aug 2005, Int. J. of Environmental Health Research 15, 4,)
Herbicides
Mesotrione: CAS# 104206-82-8
Action: A member of the Callistomone chemical class, mesotrione acts to disrupt the chlorophyll pathway of broadleaf plants resulting in a bleaching effect. It was given conditional registration in June 4, 2001 for use on field corn.