Transcript Glyphosate and Triclopyr Herbicides

Glyphosate and Triclopyr
Herbicides:
Regulatory Review of Human
Health and Ecological Effects
Hotze Wijnja, Ph.D.
Division of Crop and Pest Services
Massachusetts Department of Agricultural
Resources
Pesticide-Safety Workshop
Outline

Review of Pesticides for Registration


Federal level: EPA Pesticide Program
State Level:



Registration by Pesticide Board Subcommittee
Special Reviews for Rights of Way and Aquatic herbicides
Glyphosate and Triclopyr



Human Health and Ecological Effects
Risk assessment by US Forest Service
Risk assessment for use on Cape Cod
Levels of Review for Registration
of Pesticides
1. At the federal level by US EPA
2. At the state level by Pesticide
Board Subcommittee
3. Special reviews for specific uses:
Joint review with MassDEP for
herbicide use in
 Rights-of-Way
 Lakes and Ponds
1. EPA Regulates Pesticides
Under Authority From:

Federal Insecticide, Fungicide, and Rodenticide
Act (FIFRA)


Federal Food, Drug and Cosmetic Act (FFDCA)


Requires registration of all pesticides by EPA
Requires EPA to set pesticide tolerances for all
pesticides used in or on food
Food Quality Protection Act (FQPA)

Amended both FIFRA and FFDCA
EPA Regulatory Authority for
Pesticides

EPA must find that a pesticides poses a
"reasonable certainty of no harm" before that
pesticide can be registered for use on food/feed.

Analysis of aggregate exposure, cumulative
effects, sensitive populations (infants), and
endocrine-disrupting effects
EPA Registration Program

Evaluation of new and existing pesticides

Registration of products for pest control

Ensure protection of human health and
the environment

Registration permits the distribution, sale,
and use according to specific use
directions and requirements on the
product label

A product label is a legal document
Evaluation for Registration

Human health risk






Short-term acute effects
Long-term effects such as cancer and reproductive
Aggregate exposure (food, water and residential)
Cumulative risks (includes other pesticides)
Occupational risks
Effects on wildlife, fish and plants


Acute and chronic
Including endangered species
Evaluation for Registration

Human Health Risk






Short-term acute effects
Long-term effects such as cancer and reproductive
Aggregate exposure (food, water and residential)
Cumulative risks (includes other pesticides)
Occupational risks
Effects on wildlife, fish and plants


Acute and chronic
Including endangered species
EPA Risk Assessment
Four-step process assessment:

Step One: Hazard Identification


Step Two: Dose-Response Assessment


"The dose makes the poison.“
Step Three: Exposure Assessment


How toxic is the substance?
Dietary, residential, recreational, occupational
Step Four: Risk Characterization

RISK = TOXICITY x EXPOSURE
Risk Cup Concept


Each use of a pesticide contributes a specific
amount of exposure (risk) to humans.
This is compared to the acceptable amount of
risk (risk cup) which can not be exceeded.
Risk Management and
Regulatory Decisions

Consideration of risk assessment and peer
review

Consideration of risk mitigation measures

General Use or Restricted Use

Consideration of existing alternative pesticides

Coordination of risk management with
registrants

Label Review and Approval
Review of Registered Pesticides

Programs for re-evaluation of registered
pesticides


Registration review


Ensure adherence to the highest standards for
protection of human health and the environment
Re-evaluation on a regular cycle
Special review

Initiated when unreasonable adverse effects occur
2. Pesticide Regulation at the
State Level

MDAR is responsible for regulating the use of
pesticides in Massachusetts




Registration of pesticides
Licensing and certification of applicators
Enforcing federal and state laws and regulations
Pesticide Program Objectives


Regulate the use of pesticides
Protect human health and the environment
Pesticide Board Subcommittee

Registration of Pesticides in MA

Five members from the Pesticide Board

Director of Food Protection Program, MDPH –
Chairperson

Commissioner of MDAR or designee

Commissioner of MDPH or designee

Commissioner of MDCR or designee

Commercial Applicator
Subcommittee Registration
Classification

Subcommittee determines potential to
cause unreasonable adverse effects when
used as labeled

Classification of Registration

Not to register

Register – unclassified/ General Use

Register and classify for Restricted Use (e.g.
classification as a potential groundwater contaminant)

Register for Special Local Need
Registration Classification

Classification as State Restricted Use Pesticide
based on:

Potential for groundwater contamination

Subsurface termiticide use

Toxicity concerns

Other Subcommittee concerns
For example, toxicity to specific non-targets such
as honey bees
Groundwater Protection List
April 3, 2009
CCCGA Winter Meeting
3. Special Review for Rights-of-Way
and Aquatic Herbicides in MA

Specific Regulations for
Rights-of-Way management


Aquatic Herbicides:


Sensitive Area Materials List
Licensed use of approved herbicides (those included
in GEIR)
Special review process for herbicides to be
approved for rights-of-way and aquatic use
Special Review Process

Cooperative review by MDAR and MassDEP

Scientific review of herbicide products includes:





Physical and chemical characteristics
EPA registration standard and status
Primary and secondary data sources
If necessary, additional data will be requested from
registrant
Review addresses both active ingredients and “other”
or “inert” ingredients
Rights-of-Way Management
Regulations (333 CMR 11.00)

Provide provisions for sensitive areas within
rights-of-way

Sensitive area restrictions include:


Only herbicides listed on the “Sensitive Area
Materials List” shall be used
Criteria and procedures for review of herbicides
for use within sensitive areas are established in
a Cooperative Agreement between MDAR and
MassDEP (1987)
Sensitive Area Materials List

Herbicides specified to be acceptable for use in
sensitive areas

Currently Listed Active Ingredients:






Glyphosate
Metsulfuron-methyl
Sulfometuron-methyl
Fosamine
Imazapyr
Triclopyr
Protocol for Active Ingredients


Environmental fate and transport characteristics
Transport





Water solubility
Partitioning characteristics
Vapor pressure (volatility)
Speciation at ambient pH
Persistence



Hydrolysis half-life
Photolysis half-life
Soil half-life
Environmental Fate Evaluation

Supported by computer modeling by using EPAapproved models for environmental exposure
assessments.

Models generate predicted environmental
concentrations in soil and water for situations
specified with the input parameters, including



Chemical properties
Application characteristics
Soil and meteorological input
Toxicity Criteria

Mammalian toxicity

Acute:
LD50 values; Irritant effects

Chronic/ Subchronic

No Observed Adverse Effect Levels (NOAEL)

Lowest Observed Adverse Effect Levels (LOAEL)

Reproductive and developmental toxicity

Carcinogenicity

Mutagenicity
Aquatic Life Toxicity Criteria

Acute (fish and invertebrates)



Lethal Concentration (LC50) values
Chronic/Subchronic

No Observed Effect Concentration

Lowest Observed Effect Concentration
Reproductive and developmental toxicity
AvianToxicity Criteria

Acute



Lethal Dose (LD50) values
Chronic/Subchronic

No Observed Effect Concentration

Lowest Observed Effect Concentration
Reproductive and developmental toxicity
Amphibian Toxicity Criteria

Acute



Lethal Dose (LD50) values
Chronic/Subchronic

No Observed Effect Concentration

Lowest Observed Effect Concentration
Reproductive and developmental toxicity
Risk Characterization

Based on comparison of predicted
environmental concentrations with:





“No Observed Effect Levels” or “Lowest Observed
Effect Levels”
LC50 values
Hazard Index (HI), or
Risk Quotient (RQ)
Comparison of HI or RQ with Levels of Concern
established for various classes of organisms
Sensitive Area Materials List
Examples of Active ingredients and
approved products
Review Criteria for “Other” Ingredients



Surfactants and detergents are a common
component of herbicide formulations
Concerns for potential effects on aquatic
organisms
Review protocol similar to active ingredient
protocol


Environmental fate and toxicological information will
be considered
Supplemental information may be obtained through
use predictive tools approved by EPA
List of Approved Surfactants

Recently completed a risk assessment of
commonly used surfactants in herbicide
products

Resulted in a list of approved surfactants for use
in Sensitive Areas of Rights-of-Way

New requests for herbicide products containing
surfactants that are not listed will have to
undergo a review following the same criteria
List of Approved Surfactants






Polyethoxylated ethylamines (POEA)
Alkylphenol ethoxylates (APE)
Alcohol ethoxylates (AE)
Phosphate ester ethoxylates (PE)
Organosilicones (OS)
The need for re-evalution will be considered
when new data become available
Herbicide Reviews for ROW
• Fate & transport
Active
Ingredient &
Product
Surfactants &
other
adjuvants
• Toxicological characterizations –
humans, non-target organisms
• Use & application characteristics
(e.g., Limited and No-Spray Zone;
Application Rate and Frequency)
• Exposure assessments & risk
characterization
Approved
Not Approved
Apply use restrictions
Acceptable
Still unacceptable
Components of Herbicide Review Process for Sensitive Areas of Rights-of-Way
Legislation: 333 CMR 11.00 Rights-of-Way
Management Regulations
DEQE/DFA Cooperative Agreement Relative to Section 4(1)
(E) of 333 CMR 11.00 Rights-of-Way Management
Regulations. July 1987
Statement of Policy on Restricting the Use of Surfactants as Part of
the Evaluation Process for Herbicides Proposed for Use in
Sensitive Areas of Rights-of-Way. March 1989
HERBICIDE EVALUATION TECHNICAL UPDATE No. 1
Methods for the Evaluation of Herbicides for Use in
Sensitive Areas of Rights-of-Way
June 2010
Surfactant Ecological Risk
Assessment
(Wijnja, 2010)
HERBICIDE EVALUATION TECHNICAL UPDATE No. 2
List of Approved Surfactants for Use in Sensitive Areas of Rights-ofWay – June 2010
Reference: Wijnja, H. 2010. Ecological Risk Assessment of Surfactants Associated with Herbicide Application in Rights-of-Way Areas.
Massachusetts Department of Agricultural Resources. Boston, MA
February 2011
Ver 2.0
Summary of Regulatory Review

These levels of review and evaluation for
registration and addition to the Sensitive Area
Materials List and the rigorous regulatory
process for rights-of-way are in place to ensure:

Protection from potential impacts on human
health and the environment from the selective
use of these herbicides

Allow the benefits of selective use of herbicides
to maintain rights-of-way
Glyphosate



First registered by EPA in 1974
Widely used non-selective herbicides
Mode of Action: Inhibition of plant enzyme
Acute Toxicity (mammalian)





Low by oral exposure (LD50 >4320 mg/kg (rat)
Low by dermal exposure (skin, eye) (2 g/kg)
Not a skin sensitizer
Very low by inhalation (4.43 mg/L)
Product formulations may cause irritation due to other
ingredients
Glyphosate: Chronic Toxicity



Dog study 1(yr): No effects; NOEL > 500
mg/kg/d
Rat (2 yr): decreased body weight, effects on
eyes and liver at high doses (NOEL = 362
mg/kg/d
Reproductive and Developmental Effects:




No link to effects in rats except at very high doses
Fetuses gained weight more slowly
Some fetuses had skelatal abnormalities
No reproductive effects by glyphosate, AMPA, POEA
Glyphosate: Chronic Effects

Carcinogenicity:


Animal studies have not shown evidence that
exposure to glyphosate is linked to cancer
Classified as “Evidence of non-carcinogenicity in
humans”

Endocrine Disruption: no evidence of effects

Fate in the Human Body:

Any glyphosate taken in through skin or mouth goes
through the body in less than a day
Glyphosate: Environmental Fate

In soil: break down by microbes to several
smaller compounds, ultimately to CO2, water
and salts



In water: microbial break down


Typical field half-life ranges is about 47 d
Binds strongly to soil, immobile in soil
Half-life: few days to 90 days
No significant exposure to air expected (very low
volatility)
Glyphosate: Ecotoxicity

Birds: Practically non-toxic (LD50 >200 mg/kg)

Fish: slightly to practically non-toxic (LC50 24140 mg/L); products: 1.3 – 1000 mg/L

Aquatic Invertebrates: Slightly to practically nontoxic (LC50 55-780 mg/L; products: 3-16 mg/L)

Amphibians: Moderately to slightly toxic to
product formulations (LC50 6.6-18.1 mg/L)

Honey bees: practically non-toxic

Earthworm: practically non-toxic
Triclopyr

First registered by EPA in 1979

Selective herbicide used to control woody and
herbaceous weeds in non-crop areas

Two common forms:



Triethylamine (TEA)
Butoxyethyl ester (BEE)
Mode of Action: Mimics the effects of plant
hormones (auxins)
Triclopyr

Acute Toxicity (mammalian)





Low by oral exposure (LD50 830-1847 mg/kg (rat))
Mildly irritating to corrosive to the eyes
Non-irritating to the skin of rabbits; skin sensitizer on
guinea pigs
Low toxicity by inhalation
Fate in body:


Low rate of absorption
Rapidly eliminated
Triclopyr: Chronic Effects

Rat study (13 weeks);


Dog study: (183- 228 d)



Effects on kidneys and liver at 20 mg/kg
Effects on body weight, food consumption, blood
chemistry, liver and kidneys at 20 mg/kg.
No effects at lower at 2.5 and 5.0 mg/kg doses
Fate in body: Elimination with 2 – 3 days
Triclopyr: Chronic

Carcinogenicity




No tumors in male rats and mice (2 yr study)
Increase of number of tumors in female rats and mice
Classified as: “Not classifiable as to human
carcinogenicity”
Reproductive and Developmental Effects


Rat and rabbit studies show low potential for effects
At high levels, decrease in live fetuses and skelatal
effects
Triclopyr: Environmental Fate

In soil: breaks down to several smaller
compounds, ultimately to CO2, water and salts



In water, breaks down by exposure to sunlight


Half-life ranges from 1.1 to 90 days
Mobile in soil
Half-life is 1-10 days
No significant exposure to air expected (low
volatility)
Triclopyr: Ecotoxicity

Birds: Practically non-toxic (LD50 >735 mg/kg)

Fish:



Aquatic Invertebrates:



TEA: practically non-toxic LC50 >100 mg/L);
BEE: moderately to highly toxic (LC50 0.1 - 10 mg/L )
TEA: practically non-toxic (LC50 1496 mg/L)
BEE: moderately toxic (LC50 1.7-12 mg/L)
Honey bees: practically non-toxic
USDA Forest Service
Risk Assessments
Use Pattern
 Conifer release, site preparation, noxious weed
control, and rights-of-way management
Glyphosate
 Human Health Assessment:



Low mammalian toxicity, very few specifics can be
identified
Developmental effects are most sensitive endpoint
Formulations vary around the world; some studies
from South America suggest potential endocrine and
genotoxic effects
Forest Service Risk Assessment

Risk characterization: Hazard Quotient (HQ)


HQ = Estimated Dose/ Reference Dose
Level of concern HQ > 1

Workers: minimal concern
General public: only concern for exposure by
consuming vegetation shortly after treatment

Ecological



LOC exceeded for Aquatic organisms for product
formulations with POEA;
Care should be taken with the use of such
formulations near water bodies
Forest Service Risk Assessment
Triclopyr
 Level of Concern exceeded for:



Workers based on worst-case scenarios
General public: only concern for exposure by
consuming vegetation shortly after treatment
Ecological:


Level of Concern exceeded for large mammals and
birds consuming contaminated vegetation
Sensitive non-target plants can be affected
MDAR Herbicide Assessment
on Cape Cod
Objectives:

Evaluate the fate of herbicides used in utility
rights-of-way in common soil on Cape Cod

Evaluate the effects on groundwater and surface
water for:


Human health
Ecological (aquatic life) effects
Modeling of Pesticide Fate
in Soils

Fate in soil was simulated by EPA’s Pesticide
Root Zone Model (PRZM)

Input parameters include:
 Application
rate, chemical and
environmental fate properties, soil and
vegetation characteristics, meteorological
data

Output includes:

Herbicide concentration profile in soil
Total Glyphosate in Soil (mg/kg)
Depth in Soil Profile
0.00
0 - 1 cm
1 - 2 cm
2 - 3 cm
3 - 4 cm
4 -21 cm
21 - 29 cm
29 - 41 cm
41 - 54 cm
54 - 63 cm
63 - 72 cm
72 - 81 cm
81 - 90 cm
90 - 99 cm
99 - 108 cm
108 - 117 cm
117 - 126 cm
126 - 135 cm
135 - 144 cm
144 -153 cm
153 - 162 cm
162 - 166 cm
0.50
Glyphosate
Total Triclopyr in Soil (mg/kg)
Depth in Soil Profile
0.0000
0 - 2 cm
3 - 7 cm
8 - 12 cm
13 - 17 cm
18 -27 cm
28 - 37 cm
38 - 47 cm
48 - 88 cm
89 - 128 cm
129 - 168 cm
169 - 208 cm
209 - 248 cm
249 - 288 cm
289 - 328 cm
329 - 368 cm
369 - 408 cm
409 - 448 cm
449 - 488 cm
449 -528 cm
529 -568 cm
0.0050
Triclopyr
0.0100
Groundwater Evaluation
•
Exposure of herbicides to groundwater was
simulated with SCI-GROW model
•
EPA-approved generic screening level model
•
•
Simulates high-end estimates for groundwater
concentration levels
Simulates behavior on a vulnerable site:
–
–
–
Sandy soils
Low organic content (<1%)
Shallow groundwater (avg. 14 ft)
Simulated Groundwater Concentrations
Herbicide
Simulated
Concentration
(parts-per-billion,
ppb)
Imazapyr
Glyphosate
1.46
0.0066
20000
700
Fosamine
Metsulfuronmethyl
Triclopyr
0.147
0. 027
350
8750
0.713
1750
1 Health-based
Health-Based
Standard1 or
Health Value2
(ppb)
standards represent concentrations at which a lifetime of
exposure does not result in adverse effect to human health;
2 Health value calculated based on RfD value.
Comparison with Health-Based
Standards
100000
13,700 x
lower
10000
324,000 x
lower
106,060 x
lower
1000
2,380 x
lower
2450 x
lower
Triclopyr
Model
Conc.
100
Glyphosate
10
Health
Standard
1
0.1
0.01
0.001
Imazapyr
Glyphosate
Fosamine Metsulfuron
Note the Y-axis is expressed on a log-based scale!!
Triclopyr
Surface Water Evaluation
•
Exposure of herbicides to surface water was
simulated with PRZM-EXAMS
•
The field-scale runoff/leaching model that simulates:
–
–
–
•
Runoff, erosion, plant uptake, leaching, decay, foliar wash
off, and volatilization; selected value for off-site drift
Input includes soil, vegetation and local climate data
Does not consider buffer zone
Output includes simulated herbicide concentrations
at various time intervals:
–
From initial peak concentration up to 90 day-concentration
Simulated Surface Water
Concentrations
Simulated
Concentration
(parts-per-billion,
ppb)
Ecological
Benchmark1 or
Toxicological
Endpoint2 (ppb)
(Fish, acute
effects)
Imazapyr
0.86
>50,0001
Glyphosate
Fosamineammonium
0.73
1.5
21,5001
>150,0002
Metsulfuronmethyl
0.006
670,0002
Herbicide
Comparison with Aquatic Life
Benchmarks Acute Effects
1000000
Invertebrates
Fish
36,000 x
lower
1000
3500 x
lower
29,000 x
lower
10000
800 x
lower
100000
Model Conc.
100
Aquatic Life
Benchmark
10
1
0.1
Triclopyr TEA
Glyphosate
Triclopyr BEE
Glyphosate
Conclusions

ROW herbicide are applied at relatively low rates

Simulated concentrations in ground- and surface
water are well below health-based and
ecological standards

These low exposure levels indicate minimal risk
to human health and non-target organisms
Further Reduction of Exposure

Simulations represent worst-case scenario or
high-end of exposure potential

Exposure is reduced by limited-spray zones and
no-spray zones

No-spray zones include:


50 ft from private well
10 ft from surface water or wetland
Summary




Herbicides for vegetation in rights-of-way,
aquatic systems and similar areas undergo
rigorous regulatory review
Properties and effects have been well
characterized
Conservative risk assessments indicate low risks
for humans and non-target organisms, except
plants
Following all applicable regulations and label
instructions should provide sufficient protection
while allowing herbicides as effective tools
Hotze Wijnja, Ph.D.
Environmental Chemist
Massachusetts Department of Agricultural
Resources
Phone: 617-626-1771
[email protected]
www.Mass.gov/AGR
Resources

MDAR, Division of Crop and Pest Services


EPA Office of Pesticide Programs


http://www.epa.gov/pesticides/index.htm
National Pesticide Information Center (NPIC)


http://www.mass.gov/agr/divisions/crop_inspec_servic
es_pest_services.htm
http://npic.orst.edu/
and 1.800.858.7378
USDA Forest Service

http://www.fs.fed.us/foresthealth/pesticide/risk.shtml