Docket Number: EPA–HQ–OPP–2010-0242 www.regulations.gov

United States Chemical Safety December 2010

Environmental Protection and Pollution Prevention Agency (7510P)



# Chlorine Gas Final Work Plan Registration Review December 2010Docket Number: EPA-HQ-OPP-2010-00242 www.regulations.gov

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### TABLE OF CONTENTS

Chlorine Gas Registra tion Review Team ......................................................................................... .......... 4

I. INTRODUCTION ............................................................................................................... ...................... 5

II. COMMENTS RECEIVED ON THE PRELIMINARY WORK PLAN ............................................. 5

III. RISK ASSESSMENT AND DATA NEEDS ........................................................................................ 6

IV. TIM ELINE .................................................................................................................. ......................... 12

V. GLOSSARY of TERMS & ABBREVIATIONS ................................................................................. 14Docket Number: EPA-HQ-OPP-2010-00242 www.regulations.gov

4 Chlorine Gas Registration Review Team

Human Health & Environmental Effects

Tim McMahon

Srinivas Gowda

Risk Management

Monisha Harris

Lance Wormell

Office of General Counsel Philip RossDocket Number: EPA-HQ-OPP-2010-00242 www.regulations.gov

5 I. INTRODUCTION

This is the Environmental Protection Ag ency’s (EPA or “the Agency”) Final Work Plan (FWP) for the registration review of Chlorine Gas. The work plan includes the expected registration review timeline. Th e work plan also addresses public comments received concerning the Preliminary Work Pl an (PWP) in the Summary Document which was posted in the chlorine gas registrati on review docket, and any other comments concerning the initial docket postings. Th e Summary Document provided information on what EPA knows about the pesticide and what additional risk analyses and data or information the Agency believes are needed to make a registrati on review decision.

The Agency is implementing the registration review program pursuant to Section 3(g) of the Federal Insecticide, Fungicide, and Rodenticide Act (FIFRA) and will review each registered pesticide every 15 years to de termine whether it continues to meet the FIFRA standard for registration. Changes in science, public policy and pesticide use practices will occur over time. The registra tion review program is intended to make sure that, as the ability to assess risk evolve s and as policies and practices change, all registered pesticides continue to meet th at statutory standard. The public phase of registration review begins when the initial docket is opened for each case. Information on this program is provided at: http://www.epa.gov/oppsrrd1/registration_review/

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The chlorine gas Preliminary Work Plan was published June 23, 2010. The 60-day comment period ended on August 23, 2010. The Preliminary Work Plan document is

available on www.regulations.gov , docket number EPA-HQ-OPP-2010-0242.

II. COMMENTS RECEIVED ON THE PRELIMINARY WORK PLAN

EPA received two comments during the public comment period on the initial docket, described below. In the PWP, EP A also solicited comments on three specific topics: environmental justice; water body impairment; and trad e irritants. No comments or information were received during the public comment period concerning these issues.

The comments received during the initial public comment period did not affect the data needs, work plan and timeline described in the PWP and they remain as they were presented initially in the PWP. Furthe r, this document makes final the work plan for the chlorine gas registration review process.

Comment : The FIFRA Endangered Species Task Force (FESTF) submitted a comment requesting that any technical regi strant for chlorine gas who is not a member of the FESTF (or a company having met its data compensation obligations) be asked to provide a formal offer-to-pay to FESTF for reliance on their data. In their comment, FESTF also noted that PPG Industries, Inc, Pioneer Americas LLC, Canexus U.S., Inc, Chemical Formulators, Inc., Olin Corporation and Brenntag Canada, Inc. are the leading re gistrants for chlorine gas, and that

the above mentioned are not FESTF members. Therefore, the technical registrantDocket Number: EPA-HQ-OPP-2010-00242 www.regulations.gov

6 must offer to pay FESTF to rely on FESTF submitted data or develop substantial

similar data on their own.

Response : The Agency thanks FESTF for its comment and will consider this information as it conducts the registra tion review and makes its registration

review decisions.

Comment : The Chlorine Institute, Inc. submitted a comment questioning the value of obtaining additional plan t studies (GLNs 850.4225, 850.4250, 850.4400, 850.5400) and requesting that EPA review th e numerous references sited in the Chun, et al paper submitted as part of the Chlorine Institute’s response. The Chlorine Institute also requested clarif ication on how the vegetation listed above could potentially be adversely affected by the application of chlorine as an antimicrobial pesticide.

Response : EPA thanks the Chlorine Institute for submitting additional open literature information that was not available to EPA at the time the summary document was completed. The Agency has conducted a preliminary review of

these data and believes that the information in these articles is not sufficient to satisfy the four data requirements cite d above. The Agency intends to require these four studies as initially presente d in the Preliminary Work Plan because these data are necessary to conduct a full ecological risk assessment, including an endangered species assessment based on chlo rine’s use in swimming pool water,

industrial slimicides used in recircula ting and once-through wa ter cooling towers and paper mills that potentially pass th rough water treatment plants and may be discharged into terrestrial and aquatic e nvironments. The justification for each of these studies is provide d in Appendix A of the Summary of Product Chemistry, Environmental Fate and Ecotoxicity Da ta for Chlorine Registration Review
Decision Document, p. 26-29.

III. RISK ASSESSMENT AND DATA NEEDS

A Reregistration Eligibility D ecision was completed for chlorine gas in 1999. However, to complete registration review, additional da ta are anticipated to be needed to conduct

the human health and ecol ogical risk assessments.

Human Health Risk Assessment Status

The Agency has reviewed all the availa ble information on toxicology and human exposure regarding chlorine ga s. The toxicology and exposur e databases for chlorine gas are considered adequate. Therefore, the Agen cy anticipates that no additional toxicity or exposure data will be needed for the ch lorine gas registration review case.

Further human health information is ava ilable in the document titled “Chlorine Gas: Human Health Effects Scoping Docume nt for the Registration Review Decision,” dated June 4, 2010.Docket Number: EPA-HQ-OPP-2010-00242 www.regulations.gov

7 Dietary and Drinking Wa ter Exposure and Risk

Dietary Food Exposure

Food exposure to chlorine gas and aqueous chlorine is not expected to occur because there is not a reasonable expectation that residues significantly above naturally occurring background levels would occur. Du e to the high reactivity and water solubility of chlorine and chlorine salts, residues are also not expected to accumulate or

bioaccumulate in the food chain. Therefor e, a dietary food risk assessment is not anticipated as being needed for chlorine gas in support of this registration review.

Dietary Drinking Water Exposure

The registered uses of chlorine gas and aqueous chlorine include disinfection of municipal drinking water. The EPA's Office of Water has conducted a risk assessment

for the use of chlorine in di sinfection of municipal drinking water as well as disinfection byproducts resulting from the use of chlorine in municipal drinki ng water disinfection (Stage 1 Disinfectants and Disinfection B yproducts Rule (Stage 1 DBPR: 63 FR 69390 - 69476, December 16, 1998, Vol. 63, No. 241). As a result of this assessment, a Maximum Residual Disinfectant Level of 4 mg /L for chlorine in municipal drinking water was determined as a safe level for human exposure (http://www.epa.gov/safewater/mdbp/dbp1.html). Maximum contaminant levels of disinfection byproducts were also established as a result of th is assessment. As the other registered uses of chlorine gas/aqueous chlo rine are not likely to result in contamination of surface or groundwater, and as the EPA's Office of Water has already assessed the drinking water use, the Office of Pestic ide Programs does not anticipate conducting a drinking water assessment for chlorine gas/aqueous chlorine.

Tolerances

There is a tolerance exemption for ch lorine gas (40 CFR 180.1095) “when used preharvest or postharvest in solution on all raw agricultural commodities.” There are also tolerance exemptions for both sodium hypochlorite (40CFR 180.1235) and calcium hypochlorite (40CFR 180.1054).

Aggregate and Cumulative Exposure and Risk

In examining aggregate risk, the Agency takes into account the available and reliable information concerning exposures to pesticide residues in food, drinking water, and non-occupational pesticide expo sures. For the registered us es of chlorine gas, there is no expectation that residues above background levels will o ccur to chlorine in the diet from food contact or food uses. Therefore, th ere is no expectation that exposure in the

diet from food contact or food uses of chlori ne gas will result in an exposure that would be considered in an aggregate risk assessmen t, because this level would be no different than background levels that humans are exposed to on a daily basis. With respect to the disinfection of municipal dri nking water, a maximum residual disinfectant level of 4mg/LDocket Number: EPA-HQ-OPP-2010-00242 www.regulations.gov

8 for chlorine residue has been established by the Agency’s Office of Water which has

been determined to be a safe level for human exposure. Th erefore, this exposure would not contribute to an increased aggregate risk, as it has already been pointed out that there is no increased dietary exposure over bac kground, and the drinking water disinfectant level of 4 mg/L for chlorine had been determ ined to be a safe level for human exposure. Together then, dietary and dr inking water exposures do not co ntribute to an increased risk. Non-dietary residential de rmal and incidental oral e xposures could result from use of chlorine gas in swimming pools. The Agen cy will need to consid er the magnitude of these exposures, the health effects that have been reported from de rmal and incidental oral exposures to chlorine, the dose levels at which these effects have been reported, and the relationship of these eff ects to actual human exposures to determine whether an aggregate assessment is appropriate. It shoul d be noted that use of proper application methods and use of trained personnel in the use of chlorine gas would likely result in minimal to no exposure from this use.

Section 408(b)(2)(D)(v) of FFDCA require s that, when considering whether to establish, modify, or revoke a tolerance, th e Agency consider “available information” concerning the cumulative effects of a part icular pesticide's residues and “other

substances that have a common mechanism of toxicity.” EPA has not yet determined whether chlorine gas has a common mechan ism with other compounds; consequently, a cumulative assessment will not be performed at this time.

Occupational and Residential Exposure and Risk

An occupational and/or residential exposur e assessment is required for an active ingredient if (1) certain toxi cological criteria are triggere d and (2) there is potential exposure to handlers (mixers, loaders, applicat ors, etc.) during use or to persons entering treated sites after application is complete. Because chlorine gas is metered into water through closed systems in manufacturing proces ses or from large stationary containers such as tank cars, tank trucks, and cylinders , the Agency believes that occupational and post-application exposure to ch lorine gas, including exposur e of pool service operators and bystanders is not significant provided prope r application methods are followed. These application methods are presented in pamphlets published by the Chlorine Institute, available at: http://www.chlorineinstitute.org/Bookstor e/content.cfm?ItemNumber=3637&navItemNu mber=3638).

Anticipated Physical/Chemical Property Data Needs

All product chemistry data requirements have been fulfilled for chlorine gas. Therefore, it is anticipated that additional pr oduct chemistry data will not be needed for the active ingredient chlorine gas.

Further information is available in the “Summary of Product Chemistry, Environmental Fate, and Ecotoxicity Data for the Chlorine Gas Registration Review Decision Document,” dated June 3, 2010.Docket Number: EPA-HQ-OPP-2010-00242 www.regulations.gov

9 Environmental Fate and Ecological Risk Assessment and Data Needs

The Agency has reviewed the environmental fate and ecological hazard databases for chlorine gas. Based on its review, EPA be lieves risk assessments are needed to ensure that the chlorine gas registration review cas e meets FIFRA standards. The Agency will complete the environmental fate and ecological hazard risk assessments presented below.

• Environmental Fate

• Ecological hazard

• Endangered species assessment

Further information is available in the “Summary of Product Chemistry, Environmental Fate, and Ecotoxicity Data for the Chlorine Gas Registration Review Decision Document,” dated June 3, 2010.

The Agency needs to conduct ecological risk assessments for chlorine used in once-through water cooling towers for control of microbiological gr owth and that likely would be discharged into effluents and surface waters. Therefore, the Agency anticipates needing ecotoxicity data for chlorine that is of potential concern for once-through water cooling towers uses of chlorine. The followi ng ecotoxicity data are needed to conduct an ecological risk assessment:

Anticipated Ecological Data Needs

o (GLN 850.4225) seedling emergence, Ti er II - dose response study on rice ( Oryza sativa );

o (GLN 850.4250) vegetative vigor, Ti er II - dose response study on rice ( Oryza sativa );

o (GLN 850.4400) aquatic plant growth (a quatic vascular plant toxicity), Tier II - dose response study on floating macrophyte Lemna gibba ; and

o (GLN 850.5400) aquatic plant growth (a lgal toxicity), Tier II - dose response studies on ( Selenastrum capricornutum (green algae), Anabaena flos- aquae (blue-green cyanobacteria), Navicula pelliculosa (freshwater diatom), and Skeletonema costatum (marine diatom ).

Endangered Species

The Agency has not conducted a risk assessment that supports a complete endangered species determination for chlori ne gas. The ecological risk assessment planned during registration review will allow the Agency to determine whether chlorine gas use has “no effect” or “may affect” fede rally listed threatened or endangered species (listed species) or their designated critical ha bitats. When an assessment concludes that a pesticide’s use “may affect” a listed species or its designated critical habitat, the Agency

will consult with the U.S. Fish and Wildlife Service and/or National Marine Fisheries Services (the Services), as appropriate.Docket Number: EPA-HQ-OPP-2010-00242 www.regulations.gov

10 Incidents

The toxicological review of chlorine by the Agency for Toxic Substances and Disease Registry (ATSDR, 2002) summarizes an extensive database regarding human exposure to chlorine gas by the inhalation, oral, and dermal routes of exposure.

With respect to inhalation exposure, deat h from chlorine gas used as a chemical weapon in World War I was noted. Causes ofdeath from this exposure were bronchopneumonia, lobar pneumonia, purulent pleurisy, and tuberculous meningitis. The concentration of exposure causing death was not known in this circumstance. More recent incidents involving exposure to chlorine gas as a result of rail car accidents in which chlorine gas was released also did not note actual levels produc ing lethality, but as noted in the ATSDR review, “P rater (1990) indicates that c oncentrations of 400 ppm can

be lethal to humans in 30 minutes and th at immediate death follows inhalation of a concentration of 1,000 ppm. Concentr ations between 1,000 and 1,200 ppm for 30 minutes are lethal to humans according to a re view of earlier data from various American authors by Withers and Lees (1985b).” As migh t be expected, the resp iratory tract is the primary target of inhalation e xposure to chlorine gas, and to xicity resulting from such exposure is manifest upon the tissues a nd organs of the re spiratory tract.

From oral exposure, death in humans has been reported from ingestion of 200 mL of a solution containing 3–6% chlorine (as sodium hypochlorite) (ATSDR, 2002). Regarding accidental ingesti on, only minor effects on the ga strointestinal tract were observed in data compiled by Pike et al. ( 1963), who reviewed 129 cas es of children who ingested Clorox® and reported that no comp lications of consequences were found. Sixtyfive cases were examined by esophagoscopy within 96 hours of the ingestion and only 2 showed evidence of esophageal injury. The children were between 12 month and 7 years old and the amounts of bleach ingested rang ed from “1⁄2 ounce to 1 cup (ATSDR, 2002).

With respect to dermal exposure, the AT SDR review notes that “No studies were located regarding respiratory, cardiovasc ular, gastrointestinal, hematological, musculoskeletal, hepatic, renal, endocrine, and body weight effect s in humans or in animals following dermal exposure to aqueous chlorine.” However, it is known that dermal exposure to chlorine is extremely irritating to skin.

From OPP’s Incident Data System, th e following information was obtained on chlorine gas. The reported routes of exposure for the 324 incident cases involving chlorine gas-specific incidents were inhalation (99.7%), ocular (38%), and dermal (10%).

It should be noted that in many cases, more than one route of exposure applied for an individual incident case (e .g., inhalation and ocular). The most common symptoms reported for the routes of exposure are listed below:

• Inhalation exposure ( headache (26%), di fficulty breathing/shortness of breath (24%), sore throat/throat irritation (22%), coughing (21 %), respiratory irritation (14%), nausea (11%), ch est pain/tightness (10%), nasal irritation (8%),Docket Number: EPA-HQ-OPP-2010-00242 www.regulations.gov

11 asthma/wheezing (7%), vomiting (6%), and dizziness/lightheadedness (6%). In many cases more than one symptom was reported for each exposure route.

• Ocular exposure (eye irri tation/burning/pain )(100%).

• Dermal exposure (skin irri tation/burning) (100%).

Aqueous Chlorine Related Incidents

The reported routes of exposure for the 17 incidence cases involving aqueous chlorine incidents were inhalation (59%), ingestion (29%), dermal (18%) and ocular (12%). It should be noted that in many cases , more than one route of exposure applied for an individual incident case (e.g., inha lation and dermal). The most common symptoms reported for the routes of exposure are listed below:

• Inhalation exposure (difficulty breathing/s hortness of breath (50%), respiratory irritation (30%), skin irritation/burns (30 %), sore throat/throat irritation (20%), digestive system irritation (20%), head ache (20%), coughing (20%), impaired cognitive ability/psychologi cal effects (20%), nausea (6%), chest pain/tightness (10%), nasal irritation (10%), asthma/w heezing (10%), dizziness/lightheadedness (10%), and weakness (10%)). In many cases more than one symptom was reported for each exposure route.

• Ingestion exposure (vomiting (100%), sore throat/throat irri tation (60%), and digestive system irritation (20%)).

• Dermal exposure (skin irritation/burns (100%))

• Ocular exposure (eye irritation/burning/pain (100%)).

Adverse Ecological Incidents

The Agency maintains a database system (Ecological Incident Information System or EIIS) to track and evaluate accidental kills associated with pesticide use. The likelihood that a particular pesticide caused the incident is classified as “highly probable”, “probable”, “possible”, or “unlikely”, based on the information contained in the incident report. A

review of the EIIS database for ecological incidents involving chlorine (PC Code 020501 ) was completed on 05/12/2000. A summary of the results are presented below.

For chlorine, one incident report was filed in which unknown species of fish were killed in a lake upon a spill of chlorine from a water treatment plant. The number of fish killed were unknown. The certainty index was highly probable for the incident and a substantial spill of chlorine will kill fish. The report was filed in 2000.

This incident data is consistent with the available acute toxicity data indicating that

chlorine is very highly toxic to fish.

Endocrine Disruptor Screening Program As required under FFDCA section 408(p), EP A has developed the Endocrine Disruptor Screening Program (EDSP) to determine whet her certain substances (including pesticide active and other ingredients) may have an effect in humans or wildlife similar to an effect produced by a “naturally occurring estrogen, or other such endocrine effects as theDocket Number: EPA-HQ-OPP-2010-00242 www.regulations.gov

12 Administrator may designate.” The EDSP empl oys a two-tiered approach to making the statutorily required determinations. Tier 1 cons ists of a battery of 11 screening assays to identify the potential of a chemical substan ce to interact with th e estrogen, androgen, or thyroid (E, A, or T) hormona l systems. Chemicals that go through Tier 1 screening and are found to have the potential to interact with E, A, or T hormonal systems will proceed to the next stage of the EDSP where EPA will determine which, if any, of the Tier 2 tests are necessary based on the available data. Ti er 2 testing is designed to identify any adverse endocrine related effects caused by th e substance, and esta blish a dose-response relationship between the dose and the E, A, or T effect. Between October 2009 and February 2010, EPA issued test orders/data ca ll-ins for the first group of 67 chemicals, which contains 58 pesticide active ingredients and 9 inert ingredients. This list of chemicals was selected based on the potential for human exposure through pathways such as food and water, residential activity, and cer tain postapplication agricultural scenarios.

This list should not be construed as a lis t of known or likely endocrine disruptors. Chlorine gas is not among the group of 58 pestic ide active ingredients on the initial list to

be screened under the EDSP. Under FFDCA s ec. 408(p) the Agency must screen all pesticide chemicals. Accordingly, EPA anticipates issuing future EDSP test orders/data call-ins for all pesticide active ingredients.

For further information on the status of the ED SP, the policies and procedures, the list of 67 chemicals, the test guidelines and the Tier 1 screening battery, please visit our

website: http://www.epa.gov/endo/

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IV. TIMELINE

The EPA has created the following estimated timeline for the completion of the chlorine gas registration review case. The Agency anticipates requiring additional data and residential, occupational and ecological exposure assessments for this registration

review case.

Anticipated Schedule

Activities Estimated

Month/Year Phase 1: Opening the docket
Open Public Comment Period for Chlori ne Gas Docket Completed June 2010
Close Public Comment Period Completed August 2010
Phase 2: Case Development

Develop Final Work Plan (FWP) Completed December

2010

Issue DCI November 2011

Data Submission November 2012
Open Public Comment Period for Prelim inary Risk Assessments March 2014

Close Public Comment Period June 2014Docket Number: EPA-HQ-OPP-2010-00242 www.regulations.gov

13 Phase 3: Registration Review Decision
Open Public Comment Period for Propos ed Reg. Review Decision September 2015

Close Public Comment Period December 2015 Final Decision and Begin Post-Decision Follow-up 2016 Total (years) 6

Next Steps

The Agency plans to develop a Data Call-In for this pesticide and expects to issue

it in November 2011.Docket Number: EPA-HQ-OPP-2010-00242 www.regulations.gov

14 V. GLOSSARY of TERMS & ABBREVIATIONS

ai Active Ingredient AR Anticipated Residue ASTM American Society for Testing and Materials

AWPA American Wood Preserver’s Association

CBI Confidential Business Information CFR Code of Federal Regulations cPAD Chronic Population Adjusted Dose

CSF Confidential Statement of Formula CSFII USDA Continuing Surveys for Food Intake by Individuals

DCI Data Call-In DEEM Dietary Exposure Evaluation Model DFR Dislodgeable Foliar Residue DNT Developmental Neurotoxicity DWLOC Drinking Water Level of Comparison

EC Emulsifiable Concentrate Formulation EDWC Estimated Drinking Water Concentration

EEC Estimated Environmental Concentration

EP End use Product EPA Environmental Protection Agency

EUP End-Use Product FDA Food and Drug Administration FIFRA Federal Insecticide, Fungicide, and Rodenticide Act FFDCA Federal Food, Drug, and Cosmetic Act FQPA Food Quality Protection Act FOB Functional Observation Battery GENEEC Tier I Surface Water Computer Model

IR Index Reservoir

LC 50 Median Lethal Concentration. A statistically derived concentration of a substance that can be expected to cause death in 50% of test animals. It is usually expressed as the weight of substance per weight or volume of water, air or feed, e.g., mg/l, mg/kg or ppm.

LD 50 Median Lethal Dose. A statistically deri ved single dose that can be expected to

cause death in 50% of the test animals when administered by the route indicated (oral, dermal, inhalation). It is expressed as a weight of substance per unit weight of animal, e.g., mg/kg.

LOC Level of Concern

LOAEL Lowest Observed Adverse Effect Level μg/g Micrograms Per Gram μg/L Micrograms Per Liter mg/kg/day Milligram Per Kilogram Per Day mg/L Milligrams Per Liter MOE Margin of Exposure

MRID Master Record Identifi cation (number). EPA's system of recording and tracking

submitted studies. MUP Manufacturing-Use Product NA Not Applicable NAWQA USGS National Ambient Water Quality Assessment NPDES National Pollutant Discharge Elimination System NR Not Required

NOAEL No Observed Adverse Effect Level OPP EPA Office of Pesticide Programs OPPTS EPA Office of Prevention, Pesticides and Toxic Substances PAD Population Adjusted DoseDocket Number: EPA-HQ-OPP-2010-00242 www.regulations.gov

15 PAIRA Pure Active Ingredient Radiolabelled PCA Percent Crop Area PDP USDA Pesticide Data Program PHED Pesticide Handler's Exposure Data

PHI Preharvest Interval phr Pounds Per Hundred ppb Parts Per Billion PPE Personal Protective Equipment ppm Parts Per Million PRZM/EXAMS Tier II Surface Water Computer Model Q 1 * The Carcinogenic Potential of a Compound, Quantified by the EPA's Cancer

Risk Model RAC Raw Agriculture Commodity RED Reregistration Eligibility Decision REI Restricted Entry Interval

RfD Reference Dose RQ Risk Quotient RTU Ready to Use SCI-GROW Tier I Ground Water Computer Model SAP Science Advisory Panel SF Safety Factor SLN Special Local Need (Registrati ons Under Section 24©) of FIFRA) TGAI Technical Grade Active Ingredient TEP Typical End-Use Product USDA United States Department of Agriculture UF Uncertainty Factor

WPS Worker Protection Standard