TABLE OF CONTENTS

Appendix "H"

Santa Clara Valley Water District

District Use Pesticide
Literature Review

March 27, 2001

Thomas Reid Associates

1.0 Methodology      8
1.1 Sources      8
1.2 Toxicity     10
1.3 Exposure Scenarios      13
1.4 Ground water contamination      16
1.6 References     18
1.6 Report Preparers      25
2.0 Herbicides     26
2.1 Glyphosate     26
2.1.1 Technical information      26
2.1.1.1 Use      26
2.1.1.2 Chemistry     26
2.1.1.3 Mode of action     26
2.1.1.4 Products and formulation     26
2.1.1.5 Regulatory status     27
2.1.1.6 District use and application      27
2.1.2 Public health      27
2.1.2.1 Acute toxicity     27
2.1.2.2 Subchronic toxicity      28
2.1.2.3 Chronic toxicity     29
2.1.2.4 Carcinogenic effects     29
2.1.2.5 Mutagenic effects     29
2.1.2.6 Reproductive effects     29
2.1.2.7 Teratogenic effects     29
2.1.2.8 Organ toxicity and systemic effects     29
2.1.2.9 Fate in humans and animals      30
2.1.2.10 Occupational and residential exposure     30
2.1.2.11 Effects of inert ingredients and surfactant     30
2.1.2.12 Controversy over health effects     31
2.1.3 Environmental safety     34
2.1.3.1 Label limitation      34
2.1.3.2 Ecological effects     34
2.1.3.3 Environmental fate     35
2.1.3.4 Controversy over environmental effects      36
2.2 Oryzalin     38
2.2.1 Technical information     38
2.2.1.1 Use     38
2.2.1.2 Chemistry     38
2.2.1.3 Mode of action     38
2.2.1.4 Products and formulation     38
2.2.1.5 Regulatory status     38
2.2.1.6 District use and application     38
2.2.2 Public health      38
2.2.2.1 Acute toxicity     38
2.2.2.2 Subchronic toxicity     39
2.2.2.3 Chronic toxicity     39
2.2.2.4 Carcinogenic effects     39
2.2.2.5 Mutagenic effects      39
2.2.2.6 Reproductive effects     39
2.2.2.7 Teratogenic effects     39
2.2.2.8 Organ toxicity and systemic effects     39
2.2.2.9 Fate in humans and animals      40
2.2.2.10 Occupational and residential exposure     40
2.2.2.11 Effects of inert ingredients     40
2.2.2.12 Controversy over health effects     40
2.2.3 Environmental safety     40
2.2.3.1 Label limitation     40
2.2.3.2 Ecological effects     41
2.2.3.3 Environmental fate     41
2.2.3.4 Controversy over environmental effects     41
2.3 Chlorsulfuron      43
2.3.1 Technical information     43
2.3.1.1 Use      43
2.3.1.2 Chemistry     43
2.3.1.3 Mode of action      43
2.3.1.4 Products and formulation      43
2.3.1.5 Regulatory status     43
2.3.1.6 District use and application     43
2.3.2 Public health      43
2.3.2.1 Acute toxicity      43
2.3.2.2 Subchronic toxicity      44
2.3.2.3 Chronic toxicity      44
2.3.2.4 Carcinogenic effects      44
2.3.2.5 Mutagenic effects      44
2.3.2.6 Reproductive effects     44
2.3.2.7 Teratogenic effects     44
2.3.2.8 Organ toxicity and systemic effects      44
2.3.2.9 Fate in humans and animals      44
2.3.2.10 Occupational and residential exposure      44
2.3.2.11 Effects of inert ingredients     44
2.3.2.12 Controversy over health effects      44
2.3.3 Environmental safety      44
2.3.3.1 Label limitations      44
2.3.3.2 Ecological effects      45
2.3.3.3 Environmental fate      45
2.3.3.4 Controversy over environmental effects     45
2.4 Clopyralid     46
2.4.1 Technical information      46
2.4.1.1 Use      46
2.4.1.2 Chemistry      46
2.4.1.3 Mode of action      46
2.4.1.4 Products and formulation      46
2.4.1.5 Regulatory status      46
2.4.1.6 District use and application      46
2.4.2 Public health      46
2.4.2.1 Acute toxicity      46
2.4.2.2 Subchronic toxicity      47
2.4.2.3 Chronic toxicity      47
2.4.2.4 Carcinogenic effects      47
2.4.2.5 Mutagenic effects      47
2.4.2.6 Reproductive effects      47
2.4.2.7 Teratogenic effects      47
2.4.2.8 Organ toxicity and systemic effects      48
2.4.2.9 Fate in humans and animals     48
2.4.2.10 Occupational and residential exposure      48
2.4.2.11 Effects of inert ingredients     48
2.4.2.12 Controversy over health effects      48
2.4.3 Environmental Safety     48
2.4.3.1 Label limitation      48
2.4.3.2 Ecological effects      48
2.4.3.3 Environmental fate      49
2.3.3.4 Controversy over environmental effects      49
2.5 Pendimethalin      50
2.5.1 Technical information      50
2.5.1.1 Use      50
2.5.1.2 Chemistry      50
2.5.1.3 Mode of action      50
2.5.1.4 Products and formulation      50
2.5.1.5 Regulatory status      50
2.5.1.6 District use and application     50
2.5.2 Public health      50
2.5.2.1 Acute toxicity      50
2.5.2.2 Subchronic toxicity      50
2.5.2.3 Chronic toxicity      50
2.5.2.4 Carcinogenic effects     51
2.5.2.5 Mutagenic effects     51
2.5.2.6 Reproductive effects     51
2.5.2.7 Teratogenic effects     51
2.5.2.8 Organ toxicity and systemic effects      51
2.5.2.9 Fate in humans and animals      51
2.5.2.10 Occupational and residential exposure      51
2.5.2.11 Effects of inert ingredients      51
2.5.2.12 Controversy over health effects      52
2.5.3 Environmental safety      52
2.5.3.1 Label limitations      52
2.5.3.2 Ecological effects      52
2.5.3.3 Environmental fate      52
2.5.3.4 Controversy over environmental effects      53
2.6 Sulfometuron-methyl      54
2.6.1 Technical information      54
2.6.1.1 Use      54
2.6.1.2 Chemistry      54
2.6.1.3 Mode of action      54
2.6.1.4 Products and formulation      54
2.6.1.5 Regulatory status      54
2.6.1.6 District use and application      54
2.6.2 Public health      54
2.6.2.1 Acute toxicity      54
2.6.2.2 Subchronic toxicity      55
2.6.2.3 Chronic toxicity      55
2.6.2.4 Carcinogenic effects      55
2.6.2.5 Mutagenic effects      55
2.6.2.6 Reproductive effects      55
2.6.2.7 Teratogenic effects      55
2.6.2.8 Organ toxicity and systemic effects      55
2.6.2.9 Fate in humans and animals      56
2.6.2.10 Occupational and residential exposure      56
2.6.2.11 Effects of inert ingredients      56
2.6.2.12 Controversy over health effects      56
2.6.3 Environmental safety     56
2.6.3.1 Label limitation      56
2.6.3.2 Ecological effects      57
2.6.3.3 Environmental fate      57
2.6.3.4 Controversy over health effects      58
2.7 Triclopyr      59
2.7.1 Technical information      59
2.7.1.1 Use      59
2.7.1.2 Chemistry      59
2.7.1.3 Mode of action      59
2.7.1.4 Products and formulation      59
2.7.1.5 Regulatory status      59
2.7.1.6 District use and application      59
2.7.2 Public health      60
2.7.2.1 Acute toxicity      60
2.7.2.2 Subchronic toxicity      60
2.7.2.3 Chronic toxicity      61
2.7.2.4 Carcinogenic effects      61
2.7.2.5 Mutagenic effects      61
2.7.2.6 Reproductive effects      62
2.7.2.7 Teratogenic effects      62
2.7.2.8 Organ toxicity and systemic effects      62
2.7.2.9 Fate in humans and animals     63
2.7.2.10 Occupational and residential exposure      63
2.7.2.11 Effects of inert ingredients and surfactants      63
2.7.2.12 Controversy over health effects     64
2.7.3 Environmental safety     64
2.7.3.1 Label limitation      64
2.7.3.2 Ecological effects      64
2.7.3.3 Environmental fate      66
2.7.3.4 Controversy over environmental effects      67
2.8 Isoxaben      67
2.8.1 Technical information      67
2.81.1 Use      67
2.8.1.2 Chemistry      67
2.8.1.3 Mode of action      67
2.8.1.4 Products and formulation      67
2.8.1.5 Regulatory status      68
2.8.1.6 Typical application      68
2.8.2 Public health      68
2.8.2.1 Acute toxicity      68
2.8.2.2 Subchronic toxicity      68
2.8.2.3 Chronic toxicity      68
2.8.2.4 Carcinogenic effects      68
2.8.2.5 Mutagenic effects      69
2.8.2.6 Reproductive effects      69
2.8.2.7 Teratogenic effects     69
2.8.2.8 Organ toxicity and systemic effects      69
2.8.2.9 Fate in humans and animals      69
2.8.2.10 Occupational and residential exposure      69
2.8.2.11 Effects of inert ingredients      69
2.8.2.12 Controversy over health effects      69
2.8.3 Environmental safety      69
2.8.3.1 Label limitation      69
2.8.3.2 Ecological effects      70
2.8.3.3 Environmental fate      70
2.8.3.4 Controversy over environmental effects      70
3.0 Adjuvants      71
3.1 Butyl alcohol      71
3.1.1 Technical information      71
3.1.1.1 Use      71
3.1.1.2 Chemistry      71
3.1.1.3 Mode of action      71
3.1.1.4 Products and formulation      71
3.1.1.5 Regulatory status      71
3.1.1.6 District use and application      71
3.1.2 Public health      71
3.1.2.1 Acute toxicity      71
3.1.2.2 Subchronic toxicity      72
3.1.2.3 Chronic toxicity      72
3.1.2.4 Carcinogenic effects      72
3.1.2.5 Mutagenic effects      72
3.1.2.6 Reproductive effects      72
3.1.2.7 Teratogenic effects      72
3.1.2.8 Organ toxicity and systemic effects      72
3.1.2.9 Fate in humans and animals      72
3.1.2.10 Occupational and residential exposure      72
3.1.2.11 Effects of inert ingredients      72
3.1.2.12 Controversy over health effects      72
3.1.3 Environmental safety      72
3.1.3.1 Label limitations      72
3.1.3.2 Ecological effects      72
3.1.3.3 Environmental fate      73
3.1.3.4 Controversy over environmental effects      73
3.2 Polyethylene Monophenyl Ether      74
3.2.1 Technical information      74
3.2.1.1 Use      74
3.2.1.2 Chemistry      74
3.2.1.3 Mode of action      74
3.2.1.4 Products and formulation      74
3.2.1.5 Regulatory status      74
3.2.1.6 District use and application      74
3.2.2 Public health      74
3.2.2.1 Acute toxicity      74
3.2.2.2 Subchronic toxicity      74
3.2.2.3 Chronic toxicity      74
3.2.2.4 Carcinogenic effects      75
3.2.2.5 Mutagenic effects      75
3.2.2.6 Reproductive effects      75
3.2.2.7 Teratogenic effects      75
3.2.2.8 Organ toxicity and systemic effects      75
3.2.2.9 Fate in humans and animals      75
3.2.2.10 Occupational and residential exposure      75
3.2.2.11 Effects of inert ingredients      75
3.2.2.12 Controversy over health effects      75
3.2.3 Environmental safety      75
3.2.3.1 Label limitations      75
3.2.3.2 Ecological effects      75
3.2.3.3 Environmental fate      75
3.2.3.4 Controversy over environmental effects      76
4.0 Rodenticides      77
4.1 Chlorophacinone      77
4.1.1 Technical information      77
4.1.1.1 Use      77
4.1.1.2 Chemistry      77
4.1.1.3 Mode of action      77
4.1.1.4 Products and formulation      77
4.1.1.5 Regulatory status      77
4.1.1.6 District use and application      77
4.1.2 Public health      77
4.1.2.1 Acute toxicity      77
4.1.2.2 Subchronic toxicity      78
4.1.2.3 Chronic toxicity      78
4.1.2.4 Carcinogenic effects      78
4.1.2.5 Mutagenic effects      78
4.1.2.6 Reproductive effects      78
4.1.2.7 Teratogenic effects      78
4.1.2.8 Organ toxicity and systemic effects      79
4.1.2.9 Fate in humans and animals     79
4.1.2.10 Occupational and residential exposure     79
4.1.2.11 Effects of inert ingredients      79
4.1.2.12 Controversy over health effects      79
4.1.3 Environmental safety      79
4.1.3.1 Label limitation      79
4.1.3.2 Ecological effects      79
4.1.3.3 Environmental fate      80
4.1.3.4 Controversy over environmental effects      80
4.2 Zinc Phosphide      82
4.2.1 Technical information      82
4.2.1.1 Use      82
4.2.1.2 Chemistry      82
4.2.1.3 Mode of action      82
4.2.1.4 Products and formulation      82
4.2.1.5 Regulatory status      82
4.2.1.6 District use and application      82
4.2.2 Public health      82
4.2.2.1 Acute toxicity      82
4.2.2.2 Subchronic toxicity      83
4.2.2.3 Chronic toxicity      83
4.2.2.4 Carcinogenic effects      83
4.2.2.5 Mutagenic effects      83
4.2.2.6 Reproductive effects      83
4.2.2.7 Teratogenic effects      83
4.2.2.8 Organ toxicity and systemic effects      83
4.2.2.9 Fate in humans and animals     83
4.2.2.10 Occupational and residential exposure      83
4.2.2.11 Effects of inert ingredients      84
4.2.2.12 Controversy over health effects      84
4.2.3 Environmental safety      84
4.2.3.1 Label limitation      84
4.2.3.2 Ecological effects      84
4.2.3.3 Environmental fate      84
4.2.3.4 Controversy over environmental effects      85

1.0 Methodology

This Literature Review focuses on the pesticides used or considered for use by the Santa Clara Water District for routine maintenance including vegetation management on streams and canals and rodent control on levees and canals.

Each pesticide is described in a similar format, although the amount of information for some products is much greater than for others and information was not found for all categories for some pesticides. The Review presents information on Use, Public Health and Environmental Safety as follows:

Use

Chemistry
Mode of action
Products and formulation
Regulatory status
District use and application

Public Health
Acute toxicity
Subchronic toxicity
Chronic toxicity
Carcinogenic effects
Mutagenic effects
Reproductive effects
Teratogenic effects
Organ toxicity and systemic effects
Fate in humans and animals
Occupational and residential exposure
Effects of inert ingredients
Controversy over health effects

Environmental Safety
Label limitation
Ecological effects
Environmental fate
Controversy over environmental effects

1.1 Sources

This report compiles information from a wide range of sources: the product label, pesticide company information, EPA assessments, EXTOXNET (a collaborative multi-university project with the Institute for Environmental Toxicology and funded by the United States Department of Agriculture (USDA) Extension National Agricultural Pesticide Impact Assessment Program), and public interest, anti-pesticide citizen and activist group web information and reports (See Table A). A particular effort was made to identify areas of controversy.

Table A. Major sources used to compile Pesticide Appendix.
Major sources Description
Government and Government Affiliated
California Department of Pesticide Regulation The state agency charged with implementing and enforcing state law pertaining to pesticides. http://www.cdpr.ca.gov
EXTOXNET EXTOXNET is a collaborative multi-university project with the Institute for Environmental Toxicology and funded by the USDA Extension National Agricultural Pesticide Impact Assessment Program.
National Toxicology Program (NTP) The NTP was established in 1978 by the Secretary of Health and Human Services to coordinate toxicology research and testing activities within the Department, to provide information about potentially toxic chemicals to regulatory and research agencies and the public, and to strengthen the science base in toxicology. http://ntp-server.niehs.nih.gov/main_pages/about_NTP.html
US Environmental Protection Agency (EPA) The federal agency charged with implementing and enforcing the complex of laws pertaining to pesticides, notably FIFRA.
World Health Organization (WHO) WHO is a specialized agency of the United Nations with 191 Member States. WHO promotes technical cooperation for health among nations, carries out programs to control and eradicate disease and strives to improve the quality of human life. http://www.who.int
Public Interest
California Public Interest Research Group (CalPIRG) CalPIRG, is a statewide, environmental and consumer advocacy group that students started 23 years ago in order to tackle some of the most pressing issues of our time. Students work with experienced staff to educate the public, organize

grassroots support, involve the media, and make sure decision-makers are listening to the public interest instead of special interests. http://spirit.dos.uci.edu/calpirg/main.htm

Californians for Alternatives to Toxics (CATs) CATs is dedicated to preventing harm caused by the unwise use of toxic chemicals in the environment, particularly pesticides. To achieve this goal, CATs serves as a clearinghouse for information and strategic action. http://www.reninet.com/catz/
Natural Resources Defense Council (NRDC) NRDC uses law, science, and the support of more than 400,000 members nationwide to protect the planet's wildlife and wild places and to ensure a safe and healthy environment for all living things. http://www.nrdc.org/
Northwest Coalition for Alternatives to Pesticides (NCAP) The NCAP works to protect people and the environment by advancing healthy solutions to pest problems. http://www.pesticide.org/
Pesticide Watch Pesticide Watch is dedicated to fighting dangerous pesticide use in California communities. http://www.pesticidewatch.org/
Physicians for Social Responsibility (PSR) PSR forms a community of conscience committed to eliminating weapons of mass destruction, preserving a sustainable environment, addressing public health reform and reducing violence and its causes. http://www.labridge.com/PSR/
Rachel Carson Council (RCC) RCC is a clearinghouse and library with information at both scientific and layperson levels on pesticide-related issues. RCC develops its knowledge from literature searches and conversations with experts. It then provides answers to the public and also produces various publications clarifying pesticide dangers and bringing alternative pest controls to the public's attention. http://members.aol.com/rccouncil/ourpage/index.htm
Industry
Dow AgroSciences Manufacturer of Gallery, Garlon 3A, Garlon 4, Surflan, and Transline herbicides.
DuPont Manufacturer of Oust and Telar herbicides.
BASF Corporation Manufacturer of Pendulum WDG herbicide.
Monsanto Manufacturer of RoundUp and Aquamaster (replacement for Rodeo).

Registered Trademarks

Most of the herbicides are formulated and sold as products with registered trademark names.

Gallery, Garlon 3A, Garlon 4, Surflan, and Transline are registered trademarks of Dow AgroSciences.

Oust and Telar are registered trademarks of DuPont

Pendulum WDG is a registered trademark of BASF Corporation

RoundUp and Aquamaster are registered trademarks of Monsanto

Rodeo is a registered trademark of Dow AgroSciences; however, most of the references to Rodeo aquatic herbicide in this Literature Review pertain to the herbicide product when it was sold under that name by Monsanto.

1.2 Toxicity

Precautionary labeling includes a signal word, personal protective equipment requirements, hazard symbol, and statements of practical treatment. The label warning is normally determined by six types of acute toxicity studies and the composition of the product.

Acute toxicity refers to the immediate effects (0-7 days) of exposure to a pesticide. Highly acutely toxic pesticides can be lethal at very low doses. Narrative toxicity categories are based on the LD50, the dose (in milligrams of substance per kilogram of body weight) that kills 50% of the test animals in a standard assay, through either oral or dermal exposure routes. For inhalation exposures, the LC50 is used--the concentration in air in mg per liter that kills 50% of the test animals. See Table B for LD50-narrative equivalents. <

The acute oral, acute dermal and acute inhalation studies are used to determine the LD50 of a product via the designated route of exposure. The primary eye irritation and primary skin irritation studies measure the severity of irritation or corrosivity caused by a product. The dermal sensitization study determines whether a product is capable of causing an allergic reaction. With the exception of the dermal sensitization study, each acute toxicity study is assigned a toxicity category as defined in the table below. All products falling into toxicity categories I-IV must bear a signal word and in some cases warning symbols (EPA 1998d).

Table B. LD50-narrative equivalents
WHO Toxicity Classification Rat LD50 (mg of chemical per kg of body weight)
Class Description Solids (oral) Liquids (oral) Solids (dermal) Liquids (dermal)
Ia Extremely hazardous < 5 < 20 <10 < 40
Ib Highly hazardous 5-50 20-200 10-100 40-400
II Moderately hazardous 50-500 200-2000 100-1000 400-4000
III Slightly hazardous >500 >2000 >1000 >4000
Table 5 Unlikely to present acute hazard in normal use >2000 >3000 ----- -----
Table 6 Not classified: believed obsolete
Table 7 Fumigants not classified by WHO

Several systems are used for ranking the acute toxicity of pesticides. Active ingredients of pesticides are ranked by the World Health Organization (WHO). Formulated pesticide products (which often include inert ingredients) are given a toxicity rating by the U.S. EPA which is shown as a warning label on the pesticide product.

WHO Acute Hazard Rankings

The WHO bases its ratings on the lowest published rat oral LD50, the lethal dose (in milligrams of substance per kilogram of body weight) that kills 50% of the test animals in a standard assay (See Table B). WHO gives a hazard ranking of Ia (Extremely Hazardous) to the most hazardous pesticide active ingredients. While the WHO ratings generally reflect acute toxicity, they also take into account other toxic effects such as reproductive and developmental toxicity. WHO does not evaluate the fumigants, a class of gaseous pesticides that are generally extremely hazardous, nor does it evaluate pesticides believed obsolete or discontinued, even though some of these "obsolete" pesticides are currently registered for use in the U.S.

U.S. EPA Acute Toxicity Rankings

Formulated pesticide products (which often include inert ingredients) are given an acute toxicity rating by the U.S. EPA which is reflected in the warning label on the pesticide container. The U.S. EPA gives a warning label of Category I to the most acutely toxic pesticide products and Category IV to the least acutely toxic pesticide products.

Table C. U.S. EPA Acute Toxicity Rankings
EPA Warning Label Acute Toxicity to Rats
Category PAN Narrative Rating Warning Label Oral

LD50 (mg/kg)

Dermal

LD50

(mg/kg)

Inhalation LC50 (mg/L) Eye

Effects

Skin Effects
I Highly toxic Danger-Poison* < 50 < 200 < 0.05 ---- ----
I Highly toxic Danger < 50 < 200 < 0.05 Corrosive (irreversible destruction of ocular tissue) or corneal involvement or irritation persisting

for more than 21 days.

Corrosive (tissue destruction into the dermis and/or scarring)
II Moderately toxic Warning 50 - 500 200 - 2,000 0.05 - 0.5 Corneal involvement or irritation clearing in 8-21 days Severe irritation at 72 hours (severe erythema or edema)
III Slightly toxic Caution 500 - 5,000 2,000 - 5,000 0.5 - 2 Corneal involvement or irritation clearing in 7 days or less Moderate irritation at 72 hours (moderate erythema)
IV Practically nontoxic None › 5,000 › 5,000 > 2 Minimal effects clearing in less than 24 hours Mild or slight irritation (no irritation or slight erythema)

*This signal word is used for acute systemic poisons.

The different toxicity categories are based on the LD50, the lethal dose (in milligrams of substance per kilogram of body weight) that kills 50% of the test animals in a standard assay. For inhalation exposures, the LC50 is used---the concentration in air in mg per liter that kills 50% of the test animals.

Active ingredients can be similarly ranked for toxicity on the basis of LD50 values. Thus, warning labels for single-active-ingredient pesticide products containing technical grade active ingredients over 90% pure can serve as a reasonable proxy for the toxicity of the active ingredient.

U.S. EPA-OPP Carcinogen List

The U.S. EPA Office of Pesticide Programs maintains a List of Chemicals Evaluated for Carcinogenic Potential, which classifies pesticides by their role in causing cancer in humans and laboratory animals. The process by which chemicals are ranked involves first selecting the chemicals to evaluate, than bringing together a panel of scientists who evaluate the available data and make a decision about a cancer ranking based on the weight of the evidence. The data evaluated includes both epidemiological studies on humans exposed to the chemical in the course of their daily lives and studies on laboratory animals. Chemicals that have been studied extensively are more likely to have an accurate rating; however, this means that newer chemicals that have been on the market for less time may not have been studied sufficiently for scientists to conduct a complete evaluation. Every registered pesticide active ingredient must be categorized as to its carcinogenic potential. EPA uses the following categories in assessing evidence of carcinogenicity are: The absence of a chemical on any of the carcinogen lists does not necessarily mean it is not a carcinogen. It may mean that it has not yet been evaluated.
Category A Known to cause cancer in humans. Generally based on epidemiological data showing sufficient evidence to support a causal association between exposure to the substance and cancer.
Category B Known to cause cancer in animals but not yet definitively shown to cause cancer in humans. These chemicals are designated "probable human carcinogens." Category B is further split into pesticides for which some evidence exists that it causes cancer in humans (B1) and those for which evidence exists only in animals (B2).
Category C Possible human carcinogens, where the data show limited evidence of carcinogenicity in the absence of human data.
Category D This category is for chemicals for which the data are either incomplete or ambiguous and is labeled "cannot be determined." This category is appropriate when tumor effects or other key data are suggestive or conflicting or limited in quantity and are thus not adequate to convincingly demonstrate carcinogenic potential for humans. In general, further chemical-specific and generic research and testing are needed to be able to describe human carcinogenic potential.
Category E Probably not carcinogenic, with no evidence of carcinogenicity in at least two adequate animal tests in different species in adequate epidemiologic and animal studies. This classification is based on available evidence and does not mean that the agent will not be a carcinogen under any circumstances.

(Table information from http://www.pesticideinfo.org/documentation/ref_toxicity.html#WHOHazardRanking)

1.3 Exposure Scenarios

Studies required for herbicide registration must increase dosage until effects occur, usually at levels much higher than would ever be present in normal use. Many of the toxic effects reported have only been observed in the lab. It is unlikely that the scenarios will exist to replicate the ill effects that occur during scientific study (e.g. force feeding, direct application of herbicide to trachea). Nearly all of the laboratory results reported are based on use of the pure pesticide or pesticide concentrate; as used by the District, the concentrate is diluted in water to approximately 1% to 5%, depending on product.

Nonetheless, credible paths of public exposure to these herbicides do exist and include herbicide drift, spill, over-spray and release. Exposure scenarios have been created in order to put the results of laboratory tests in context with real risk possibilities to the public. An exposure scenario is a hypothetical situation in which a subject could be exposed to a pesticide. The amount the subject is likely to be exposed to is determined from the District use of each pesticide product. Compare the exposure amount to the LD50 to determine the exposure risk from each scenario. For this risk assessment, several very conservative scenarios are developed. As discussed below, most of these scenarios should be regarded as extreme.

1. Herbivore. This is a maximum exposure scenario where a large application area is consumed by a small animal. The "hungry rat" weighs 0.5 kilograms (kg) and consumes all vegetation within a 10 meter square (m2) (~108 square foot) pasture that has just been sprayed with an herbicide. The mass of green vegetation would be at least 2 kg (5 lbs), otherwise there would not have been enough foliage to adsorb the spray and spray would have runoff into the ground. The scenario assumes consumption over several days but is an extreme dose for a small animal. For a larger animal, such as a goat grazing the same area, the same quantity of chemical would be divided by a larger body weight resulting in a proportionally smaller dose.

2. Child. Many of the exposure scenarios for the general public involve a child (Syracuse 1996). The "exposed child" is an important test of herbicide effect because the relationships of surface area and consumption rates to body weight result in estimated doses for young children that are higher than those for adults. The EPA recommends that dermal exposure scenarios that involve children use the following set of assumption: the child is 2 to 3 years old, weight 11 kg, and has a total body surface area of 0.6 m2 (24 lbs, 6 ft2). The child is assumed to be naked, maximizing the surface area of the body in contact with the chemical (Syracuse 1996). The child is assumed to be completely covered and the actual dose would not include chemical in spray that was absorbed by clothing, dripped off, or was washed off.

3. Adult. The "soaked sunbather" scenario addresses the risk of herbicide drift. The 50 kg sunbather is assumed to be covered with the maximum amount of herbicide in an applied area of 2m2 (110 lbs, 20 ft2). Again, it is assumed that all the herbicide in the 2m2 sprayed area is absorbed into the body. In fact, dermal absorption rates are fairly slow and the actual dose would not include chemical in spray that was absorbed by clothing, dripped off, or was washed off.

There is a relationship between the amount ingested or the surface area of body exposed and the subsequent risk. To calculate the exposure amount, the first step is to determine the District's application rate, based on District practice consistent with the product label. Table P-1, Application Rate for District Use Herbicides, lists the herbicide, the product name and the % of product which is active ingredient. The product is diluted with water for application. The application rate is the quantity of active ingredient applied to the land, expressed as pounds per acre and milligram per square meter. The concentration of active ingredient in the spray solution is expressed as grams per liter.

Although a few of the herbicides may be applied between two to four times per year, most are applied no more frequently than once per year. Therefore, we are concerned with potential acute, single exposures; subchronic and chronic exposure is likely to be extremely low for the public or their pets. Table P-2, Acute Toxicity and Exposure for District Use Herbicides, lists the LD50 for oral and dermal exposure and presents the respective doses for the exposure scenarios. It is clear that only the aggressive herbivore scenario has ingested doses approaching acutely toxic levels; the human exposure scenarios are always 100 fold or more below the toxic level.

Table P-1 shows the application rates used by the District for each pesticide. Table P-2 lists the LD50s and the potential exposure scenario level for each pesticide based on the District application rates.

Table P-1: Application Rate for District Use Herbicides


Active Ingredient Herbicide Product % active ingredient Broadcast Application Rates for Active Ingredient
pounds/acre mg/m2 spray dilution
% 		solution g/L
isoxaben Gallery 75 0.75 84.06 0.45-8.99
triclopyr Garlon 3A 44.4 1.5 168.13 1.81-9.22
triclopyr Garlon 4 61.6 1.0 112.19 1.198
sulfometuron methyl Oust 75 0.23 26.27 0.70-1.87
pendimethalin Pendulum 60 3.0 336.26 < 8.99
glyphosate Rodeo 53.8 2.7 302.63

1.5

glyphosate RoundUp Pro 41 2.5
240
2%
oryzalin Surflan 40.4 4.0 448.34 -
chlorsulfuron Telar 75 0.09 10.54 0.06% 0.056
clopyralid Transline 40.9 0.25 28.02 0.075% 3.99
Target Pro Spreader Used with Aqua-master

Garlon

surfactant .5%

.25%

R-11 surfactant

Used with Aqua-master

Garlon

surfactant .5%

.25%



Table P-2: Acute Toxicity and Exposure for District Use Herbicides



Active Ingredient


Herbicide Product		 LD50 mg/kg Exposure scenario mg/kg
Oral

(rat)

 Dermal (rabbit) Herbivore

0.5 kg animal,10m2 exposure

 Child

11 kg person, 0.6m2 exposure

 Adult

50 kg person, 2m2 exposure

isoxaben Gallery >10,000 >2000 1680 4.58 3.36
triclopyr Garlon 3A 1847 >5000 3360 9.17 6.73
triclopyr Garlon 4 1338 >2000 2240 6.12 4.49
sulfometuron

methyl

 Oust >5000 >2000 525 1.43 1.05
pendimethalin Pendulum >5000 >2000 6730 18.3 13.5
glyphosate Rodeo/ Aqua-master >5000 >5000 6050 16.5 12.1
glyphosate RoundUp Pro 5600 >5000 5600 15.3 11.2
oryzalin Surflan >10,000 >2000 8970 24.5 17.9
chlorsulfuron Telar 5545 3400 211 0.57 0.42
clopyralid Transline >5000 >5000 560 1.53 1.12
Target Pro-spreader

Used with Garlon and Aqua-master
>3500
-
R-11 Surfactant used with Garlon and Aqua-master
790
3400- 4200

1.4 Ground water contamination

Ground water is the water found in spaces between soil particles and rocks, and within cracks of the

bedrock. Ground water, stored and moved through underground aquifers, is the largest single supply of fresh water available for use by humans. In the United States, up to 50% of the population depends on ground water for drinking. However, this water supply is susceptible to contamination by human activities on the land above.

The ability of pesticides to contaminate ground water is of important concern. The draft Ground Water Protection Regulations (1/03/01) defines two types of "ground water protection areas" (GWPA): "Leaching" GWPA where pesticide may be carried directly into the ground water by infiltrating water flow, and "runoff" GWPAs where pesticides may run off of the application site and affect ground water recharge elsewhere (California Code 2001).

The determination of a ground water protection area is based on factors, such as soil type, climate, and depth to the ground water, that are characteristic of areas where legally applied pesticides or their breakdown products have been detected and verified in ground water (California Code 2001).

"Leaching ground water protection areas" are areas of land listed as "Leaching Areas" in the Department of Pesticide Regulation document EH-99-xx entitled "Ground Water Protection January 3, 2001" (California Code 2001). In Santa Clara County, leaching areas are found along the Pajaro River, between US 101 and CA 25.

"Runoff ground water protection areas" are areas of land listed as "Runoff Areas" in the Department of

Pesticide Regulation document EH-99-xx entitled "Ground Water Protection Areas," where pesticide residues are carried in runoff water to more direct routes to ground water such as dry or drainage wells, poorly sealed production wells, or soil cracks, or to areas where leaching can occur (California Code 2001). None of these areas are subject to direct District application.

None of the pesticides proposed for use by the District have been found in ground water, however some share characteristics in common with known leachers and may become further restricted in their use. Four herbicides have been identified as suspected leachers pursuant to section 13145(d) of the Food and Agricultural Code: chlorsulfuron, isoxaben, oryzalin, sulfometuron-methyl. There are currently no additional restrictions on the use of these herbicides, however, the treatment of these herbicides as if they were known leachers if under review.

Pesticide levels in ground water show pronounced seasonal variability in agricultural areas, with maximum values often following spring applications. (http://water.wr.usgs.gov/pnsp/gw/ )

1.5 Glossary of Terms and Abbreviations