_,,~EO Sl..q r:, v~ ~\9 

j 8 =u UNITED STATES ENVIRONMENTAL PROTECTION AGENCY 

S ~ "ffi WASHINGTON D.C., 20460 

)J <!) 

0 ~ 

~- ~ ~. .c.P OFFICE OF CHEMICAL SAFETY 

.,)':. r.' AND POLLUTION PREVENTION 

All. PRQ\CC.v 

MEMORANDUM 

SUBJECT: 

December 19, 2012 

Amended Product Chemistry, Environmental Fate, and Ecological Effects 

Scopif g Document in Support of Registration Review of 

Poly(liexamethylene-biguanide) hydrochloride 

I 

PC Code: 111801 DP Barcode: 407780 

;Deci&ion No.: 459677 Registration Nos.: None 

Petiti pn No(s).: NA Regulatory Action: Ecological 

Environmental Scoping Document 

for Registration Review 

Risk Assessment Type: Single chemical Case No.: 3122 

TXRNo.:NA CAS No.: 32289-58-0/27083-27-8 

MRID Nos.: See Tables 3 & 4; 40CFR: None 

Pg. nos. 9, 10, 12-16 

f.;/ ( Srini 1as Gowda, M.S. Microbiologist ~ (,t/~ Donna Randall, M.S., Senior Effects Scientist 

FROM: 

THRU: 

TO: 

Najm Shamim, Ph.D., Chemist M!--u:~ 

r ti icrobials Division (7510P) . r 

Steve Weiss, Chief ~ !Y~ Risk "I ssessment and Science Support Branch (RASSB) 

Antimicrobials Division (7 51 OP) 

;r'ike endelsohn, Branch Chief 

t.ance Wormell, Team Leader 

Rebecca von dem Hagen, Chemical Review Manager 

Regulatory Management Branch II 

Antimicrobials Division (7510P) 

Page 1 of 25 
Executive Summary 

Poly(hexamethylene) biguanide hydrochloride (PHMB·HC~), case 3122, is a biguanide 

cationic polymer used as a broad spectrum antimicrobial (effective lagaimst many types of 

microbial organisms- aerobic and anaerobic bacteria, yeasts, fung·, and molds). PHMB·HCl 

exists as a polydisperse mixture which means it consists of a mixture of differing polymer 

lengths or sizes, referred to as PHMB. PHMB·HCl is registered fot use as a fungicide, algicide, 

and sanitizer for use with swimming pools, spas and hot tubs; a materials preservative in 

architectural and industrial coatings, textiles and cellulosic material, glues and adhesives, leather 

and fresh animals skins and hides; a microbicide/microbiostat in intlustrial processes and water 

systems including cooling towers; and as a hard surface (food and tl on-food contact surfaces) 

disinfectant/sanitizer in a variety of residential and public access p mises, commercial, 

institutional, industrial premises and equipment, medical and agric ltural premises and 

equipment, and food handling storage establishments and equipmet t. 

PHMB-HCl was first registered in the United States in 1982 as an 1ctive ingredient. Currently, 

there are twelve companies with a total of 25 active product registr tions containing PHMB. 

Two of the products are registered technical products with PHMB·~Cl active ingredient 

declarations of 20% and 96.3%. The remaining 23 products are registered end-use products with 

PHMB·HCl active ingredient declarations ranging from 0.08 to 96.B%. End-use products are 

I 

formulated as flowable soluble concentrates (0.08 to 20% PHMB·HCl), ready-to-use solutions 

(0.1% to 20% PHMB·HCl), a solid soluble concentrate (96.3% PH¥B·HC1), and wet wipes 

(contains solution of 0.1% or 0.5% PHMB·HCl). Clarification on the character of the PHMB 

polymer dispersion of each of the technical products (range and distribu ion of polymer chain 

lengths and average polymer size) and their variability is needed. 

A Reregistration Eligibility Decision (RED) was issued by JEPA for PHMB·HCl in 

September 2004. At the time of the RED, PHMB hazards were chdracterized as part of the 

assessment but no quantitative risk assessment was performed. As tart of the registration 

review process, a risk assessment for those PHMB·HCl use pattern resulting in discharge of 

PHMB to water will be conducted such as industrial processes and ater systems uses such 

as cooling towers, paper mill process water, and consumer, institutipnal, commercial product 

uses resulting in down-the-drain disposal or discharge to receiving ate~s. 

While there is some understanding of the likely environmental fate of PHMB based 

on its physical and chemical properties, there is very little informat on that can be applied 

quantitatively. The likely primary dissipation pathway for PHMB is sorption and reaction 

with humic acid, suspended solids, and sediment. To conduct the registration review 

assessment for residential, commercial, institutional consumer products (e.g., pools, spas, 

hot tubs, detergent) and industrial processes and water systems, and material preservative 

wastes that may be discharged to waste water treatment plants (WtTPs), the Agency 

anticipates needing an activated sludge sorption/desorption study and an activated sludge 

respiration inhibition test with the technical grade active ingredient products. A number of 

ecological effects data are required to allow conduct of a risk assessment to the aquatic 

environment both freshwater and estuarine/marine systems (freshw ter and estuarine/marine 

fish and invertebrate acute testing, freshwater and estuarine fish early life stage testing and 

invertebrate life cycle testing, aquatic vascular and nonvascular toxicity data, and chronic 

whole sediment toxicity testing). A vi an acute oral testing is also required. 

Page 2 of25 
Introduction 

PHMB·HCl was first registered in the United States in 1982 as an active ingredient for 

use in manufacturing swimming pool sanitizers and disinfectants for use in commercial, 

industrial, and residential settings and to formulate sanitizers and disinfectants for use in food 

handling/storage establishments, premises and equipment, including food contact surfaces in 

public eating places, dairy processing equipment, and food processing equipment and utensils. 

Currently, there are 25 prod cts containing PHMB·HCl (two technical products and 23 end-use 

products) for use as algaecides, bacteriocides/ bacteriostats, fungicides/fungistats, 

microbicides/microbiostats, Jlimicide, disinfectants, and sanitizers. PHMB is registered for use 

as a fungicide, algicide, and ~anitizer in swimming pools; a materials preservative in 

architectural and industrial cchatings, textiles and cellulosic material, glues, leather, and fresh 

animals skins and hides; a mtcrobicide/microbiostat in industrial processes and water systems 

including cooling tower$; anf as a hard surface (food and non-food contact surfaces) 

disinfectant/sanitizer in a var ety of residential and public access premises, and commercial, 

institutional, industrial, medical, and agricultural premises and equipment, and food handling 

storage establishments and e ' uipment. A detailed list of use patterns and use sites of PHMB are 

listed below. 

Use Patterns and Use Sites 

I 

Swimming Pools 1 

Swimming pools, spa and hot tub water systems. 

premises. 

Food handling storage establishments and equipment 

Hard, non po ous surfaces in restaurants/eating establishments such as kitchen 

countertops, High chairs, refrigerators, and microwave ovens. 

Commercial, Institul onal and Industrial Premises and Equipment 

Hard, non-pOFous surfaces such as garbage cans, walls, floors, and stainless steel 

surfaces. 

Medical premises and equipment 

Hard, non-po ous surfaces in hospitals, nursing homes, animal laboratories and 

veterinary off ces. 

Residential and Public Access Premises 

Hard, non-porous surfaces such as tables, countertops, stovetops, sinks, cabinets, 

refrigerators, microwave ovens, high chairs, tubs, floors, glazed tiles, urinals, 

diaper pails ar d other bathroom surfaces, garbage cans, walls, floors, stainless 

steel surfaces kennel runs, pet areas, sealed stones, glazed ceramics, playground 

equipment, and picnic tables. 

Industrial processes and water systems 

Page 3 of25 
Drilling muds and packer fluids in addition to workover fluids. Oil field injection 

water and tunnel pasteurization water. Cooling towers. 

Materials Preservatives 

For use in the preservation of electrocoat resins in addition to aqueous industrial 

chemicals such as reagents, oil-in-water emulsions, water-in-oil emulsions, 

cellulose solutions, silicone emulsions and silicone dispersions, aqueous mineral 

slurries such as calcium carbonate and titanium dio:xlide as well as polymer lattices 

such as polyvinyl acetate and polyvinyl alcohol. 

For the preservation of textiles and cellulosic materi ls such as carpet, curtains, 

mops, dishcloths, wipes, sponges, tissues and non-i od ntact paper products. 

For the preservation of leather, fresh animal hides d skins prior to or during 

process mg. 

For the control of microorganisms in aqueous adhesives such as animal glues, 

latex adhesives and other synthetic and protein based glues. 

I 

A Reregistration Eligibility Decision (RED) was issued by PA for PHMB in September 

20041

• At the time of the RED, PHMB hazards were characterized as part of the assessment but 

no quantitative risk assessment was performed. To regulate the in stri&l microbiocide uses and 

associated risks to the aquatic environment, the Agency required th t la els for PHMB products 

require discharges to aquatic environments comply with a National Pollutant Discharge 

Elimination System (NPDES) permit. The only use pattern identifi

1 

d as likely to result in 

significant outdoor exposure was the oil recovery use; however, la ellanguage prohibiting use 

over or near marine/estuarine (e.g., offshore) oil fields was used to ddress these hazards. As 

part of the registration review process, risk assessments for those PHMB use patterns resulting in 

discharge of PHMB and its major degradates of concern to water w·ll be conducted such as 

applications to cooling towers; paper mill process water; consumer inst tutional, commercial 

product uses resulting in down-the-drain disposal or discharge to re1

1

ceiving waters; and oil well 

process and development uses. 

Mode of Action ~ PHMB is a me~brane active agent. PHMB interacts with e surface of cell membranes. 

As PHMB binds to the membrane, it drags acidic phospholids to thf location- reorganizing the 

membrane, creating an acidic lipid domain- surface membrane acqvity.l This aggregation of 

acidic phospho lids leads to increased fluidity and permeability of tlie mbrane resulting in the 

release of lipopolysaccharides from the outer membrane, potassiu I ion efflux, and eventual 

organism's death. 

1

http://www.epa.gov/oppsrrd 1/REDs/phmb red.pdf 

Page 4 of25 
A. Product Chemistry Summary of PHMB 

PHMB exists as a polydisperse mixture which means it consists of a mixture of polymer 

chains of different lengths on sizes, and mass (a monodisperse polymer would consist of 

polymers of the same size and mass). A single monomer unit is the hexamethylene biguanide 

unit (see the molecular structure in Table 1). Information submitted on the characterization of 

one of the technical products identifies chain lengths ranging from n = 1 to 40 mers. The 

average molecular weight for the samples tested range from n = 10 to 13 mers which indicates 

that the distribution of polyJer chain lengths in registered products varies. Additionally, the 

PHMB polymer chain does not have a single identical end group, it may end in an amine (- NHz) 

or a cyano (- CN) group being the terminal (end) group(s) based on the manufacturing process. 

A summary of the prbduct chemistry data for the monomer of PHMB, designated 

PHMB·HCl because it includes the hydrochloric acid component (HCl), is provided in Table 2. 

There has been some confusion over the range and distribution of mer length present in the 

antimicrobial PHMB use pn~ducts. The 2004 RED provides a potential chain length for PHMB 

polymer dispersion of 1 to 4? mers with an average of 12. In-house information gives differing 

characteristics: one study implies mer length of 1 to 12 mers with average of 4.5 to 5.5 mers, 

another indicates 1 to 40 mets with average of 12 mers. Literature findings for PHMB pesticidal 

products indicate polymer chain lengths of 1 to 40 mers (e.g., de Paula et al. 2011). The exact 

length, and number of mers present in the technical grade products (i.e., 20% versus 96.3%, 

versus historic in-house datal on 20%) is needed to help in understanding the fate of the 

dispersion contained in PHMB products. Without this information it is unknown how reflective 

or how bridgeable informatibn on the fate or toxicity of the PHMB polymer dispersion in the 

current 96.3% and 20% technical products are to historic fate and effects data conducted with 

20% polymer dispersions. 

Table 1. Chemical ldenti y 

PHMBHCI 

Chemical Name oly(ifninoimidocarbonyliminoimidocarbonyliminohexamethylene) hydrochloride 

Poly(iJTiinocarbonimidoyliminocarbonimidoylimino-1 ,6-hexanediyl) hydrochloride 

Common Name Poly( examethy lenebiguanide) hydrochloride 

Polyhexamethylene biguanide hydrochloride 

Polyhexanide 

Synonyms Polih xanide HCI 

Polyh,examethylene biguanide HCl 

Trade Names Vantocil P; Baquacil; Baquacil SB; Cosmoquil CQ; PHMB; VantocillB 

Molecular Weight 2 19.718 g/mol (monomer unit and includes HCl) 

PC Code 1118011 

CAS No. Open literature search put the two CAS#s together: 27083-27-8 and 32289-58-0, 

but no information is provided on the second one. ' 

Molecular Formula (Cs H/7 Ns)n . xHCI2 

2 I . Note: The molecular weight of P~ can vary as the value of 'n' (the number of mers) can be a little as I and as 

many as 12. The average for Baquacil is reported as 4.5 to 6.5. Thus the molecular weight (MW) reported in this 

document is with n= 1, one mole fhydrochloric acid (HCl) is included in the MW. This is the moiety registered 

with the Agency. 

Page 5 of25 
PHMBHCI 

Molecular Structure: 

[ l NH NH I 

II II 

NH - c - NH - c - NH - (CH 2) 6 

I • X HCl 

l 

Table 2. Product Chemistry Data Summary of PHMB·HCI I 

Guideline Physical and PHMB·HCl PHMB·HCl 

No. Chemical Properties 96.3% Solid 20% weight to volume (w/v) 

(Technical) Aqueous Solution (Technical) 

830.1550 Product identity and Refer to Table 1. Refer to 7'able 1. 

composition 

830.1800 Enforcement Mass spectroscopy (MS) Infra-Red Spectra. 

analytical methods UltraViolet Spectrophotometry N~Spectra. 

Infra-Red Spectra Capillary GC 

Nuclear Magnetic Resonance (NMR) High Performance Liquid 

Spectra Chlomatography (HPLC) 

Gas chromatography (GC) 

830.6302 Color Off white to pale yellow solid Colorless to yellowish 

830.6303 Physical State Lumpy solid Liquid 

830.6304 Odor None No1

discernible odor 

830.6313 Stability to sunlight, Stable at 3 months Staple under normal condition. 

normal and elevated Stable at 54 ± 2 degrees Celsius (

0C) for Staple for 14 days at 54 ± 2°C. 

temperature, two weeks. 

metals/metal ~:r' ange. ions Onset of decomposition: 205 to 210 oc minum, copper, iron, and zinc- no 

. ct. 

830.7000 pH 4.36 for a 1% solution at 21.7°C 5~ solution(= 1% active agent): 5.7 

830.7050 UVNisible PHMB absorption spectra maximum PH ~ absorption spectra maximum 

Absorption was not found in visible wavelength. wa~ not found in visible wavelength. 

830.7100 Viscosity Not a Liquid _3 

1 ,2.10 Pascal·second (Pa·s) 

830.7200 Melting point 78.9 - 136.3°C ------ Decomposition begins at 205 - 21 0°C. 

Melting point around 100 ° C 

830.7220 Boiling point Boiling point is not applicable since this l02°C 

product is a solid and not a liquid. 

830.7300 Density 1.26 gl cm3 at 25°C Relative density 

1. 044 at 20°C 

830.7370 Dissociation Constant pKa=4.19 at 25°C 1.2 ± 0.5 X 10-

1 at 25°C 

830.7550 Partition coefficient Log Pow = -2.62 Log Pow= -2.62 

(n-octanoVwater) 

830.7840 Solubility in water 39.0 to 43.4% w/v 23.5°C ------

830.7860 Solubility in organic Methanol : 41% w/w ±1% at 25 ±1 oc ------ solvents Ethanol : 0.5% w/w ± 0.08% at 25± I oc 

I Acetone: 2.7 ppm at 22°C 

Dichloromethane: 0.2 ppm at 22°C 

Ethyl Acetate:= 0.1 _pp_m at 22°C 

Page 6 of25 
Guideline Physical and PHMB·HCI PHMB·HCI 

No. Chemical Properties 96.3% Solid 20% weight to volume (w/v) 

(Technical) Aqueous Solution (Technical) 

' Toluene: 0.2 ppm at 22°C 

n-hexane: 0.1 ppm at 22°C 

Acetonitrile: 0.8 ppm at 22°C 

830.7950 Vapor pressure 1.5 X 10·9 mmHg at 25°C ------

Henrys Law Constant 1.05£-015 atm-m3

/mole (Calculated) ------

at 25 oc 

N/A =not applicable; TGAI = tecj mcal grade active mgredient; w/w = weight m weight 

B. Environmental ate Summary 

PHMB·HCl was orig nally registered for conventional uses and registrants had submitted 

some fate studies that were not identified in the 2004 RED. These studies are included in this 

document. However, these studies were not conducted according to the Agency's environmental 

fate test guidelines as they ere generated prior to 1984 and the Agency's test guidelines were 

generated after that date. In flddition an open literature search was conducted and data results 

from some relevant studies are also included in this summary. 

PHMB is hydrolytically and photolytically stable under abiotic conditions and is stable 

under both aerobic and anaefobic conditions. When applied to soil PHMB is not expected to 

migrate into soil to any appreciable distance. This lack of mobility is most likely due to its 

positive charges. It is desorqed on the soil surface and hence is not mobile in soils. Because it is 

not mobile in various soils, HMB discharged into aquatic systems would be expected to be 

associated with sediments arid not the water column. In a WWTP, PHMB would be expected to 

associate primarily with the t iosolids. PHMB is not expected to bioaccumulate in biota. 

As the technical gra~ products contain a mixture of polymers (e.g., monomers, dimers, 

trimers, tetramers, and = 5 to 40), and the distribution of the polymer length or size, as well as 

end groups being different (z.e., -NH2 and/or -CN), the fate chemistry is expected to potentially 

differ between the 20% PH B (historic test substance), 20% and 96.3% PHMB technicals. 

Essentially all of the fate stutlies have been conducted with V antocil IB or V antocil P which are 

20% products containing lo er molecular weight polymer chains of PHMB (characterization 

information of test substancJ is average of n=4.5 to 5.5 mers). The 96.3% PHMB is 

characterized as having a di tribution containing higher molecular weight chain polymers with 

an average of 12 mers. The rollowing discussion on the fate of PHMB is based on studies 

conducted using a 20% technical grade product with the lower molecular weight (average n=4.5 

to 5.5 mers) polymer disper ion. Information bridging the fate characteristics of these 

distributions with chain length has not been provided, so there is uncertainty in the fate 

characteristics of the longer bhain polymers in environmental media. 

Page 7 of25 
Abiotic Fate 

It has a low vapor pressure (- 10-9 mm Hg) and the Henry law constant is very low so it 

does not have a tendency to volatilize from surface water. PHMB i readily soluble in water 

(39.0 to 43.4% w/v 23.5°C) but shows little solubility in hydrocarbbns. Critical micelle 

concentration (CMC), i.e. point where micelles form, in water has een reported in literature for 

an unknown PHMB product to range from 1 x 10-3 to 5 X 10-2 mole per liter (de Paula et al., 

2011). 

Hydrolysis 

PHMB is hydrolytically stable under abiotic conditions and ndj goes < 10% 

degradation at pHs 5, 7, and 9 (MRID 43622301). 

Recently the Food and Drug Administration (FDA) publish d a hydrolysis study (Lucas, 

2012) on PHMB which is registered with FDA for germicidal uses. 1 No hydrolysis of PHMB in 

water occurred. Even after 60 days in a phosphate buffered saline solution 90% of PHMB was 

still present (only 10% degraded). Under acidic conditions (HCl c ncentration at 1 Molar (M)3 

or 0.01 M conditions) PHMB did hydrolyze immediately, but in a 1 M3 olution of sodium 

hydroxide (NaOH), it only took 30 days to degrade. Even when it1 ydr9lyzes it doe dot follow a 

first order kinetics as PHMB by its very nature is not a simple hom geneous polymer but is a 

polymer with repeating hexamethylene links the number of which aries. . 

Adsorption/Desorption 

PHMB was found to rapidly absorb to soils (MRID nos. 00 177931 and 93191024). In a 

batch equilibrium study for soil e4

C]PHMB was rapidly adsorbed 'fith equilibrium reached 

within the first 16 hour shaking period. However, no Kacts or Koc were reported. 

Similarly in an aged soil column leaching study (MRID# 9) 910!24) radio-labeled 

[ 

14C]PHMB was incubated with calcareous clay loam, coarse sand, b d course sandy loam soils 

for four weeks under aerobic conditions. No radioactivity was det~1 ted in the leachate when 35 

em long soil columns were leached with 68 em rain over a two mo period. About 90-95% of 

the PHMB was found to stay within the top five inches of soils ove a period of two months. 

Even if biodegradation products are formed, they along with the p ent PHMB appear to bind 

very strongly to the soils and are not extractable. 

3 The FDA paper reported the concentration in terms of Normality (N) and not Molarity (M) for the reagents; in the 

case ofHCl and NaOH normality and molarity are one and the same. 

Page 8 of25 
In addition to looking at hydrolysis, the FDA study (Lucas, 2012) performed a screening 

level study on PHMB leaching using: a clay soil, a MD soil, a potting soil, a sandy soil and old 

concrete pieces. The presence of PHMB leaching from clay soil, potting soil, and concrete was 

not detected. Only in sandy soil was the presence of PHMB detected. 

Bioaccumulation 

Since the log Kow for PHMB is very low ( -2.26), PHMB is not likely to bioaccumulate in 

aquatic organisms. 

Biotic Fate 

Aerobic Soil Metabolism 

In an aerobic soil me 1abolism study (MRID nos. 00077932 and 93191023), conducted 

using three United States soils. PHMB degraded by only 20% at the end of one year at pHs 6.0, 

7.0, and 7.5. Thirty to forty percent (30-40%) of PHMB was extracted from the soil. Thus 

PHMB does not biodegrade j erobically in various soils but rather stays around on the top soil. 

Anaerobic Soil Metabolism 

An anaerobic soil tabolism study was conducted with one soil at a soil pH of 7 (MRID 

nos. 00077932 and 93191022). At the end of one year only 10.6% ofPHMB was estimated to 

have degraded. Thus PHMB does not show any tendency to biodegrade under anaerobic soil 

conditions. 

In all the metabolis studies discussed above the product tested was Baquacil (20% 

PHMB), mixed with carbon-14 (

14C) radiolabeled PHMB. All of the metabolism studies 

discussed above were condu ted under non- guideline test conditions. But these studies do 

provide data points from which the conclusions drawn are: 

Biode radabili in l ctivated Stud e and Activated Stud e Inhibition 

Both a semicontinuous and a continuous activated sludge treatment study (Acc#234289) 

using radiolabeled PH:NJB were conducted in the late 1970's. The protocols for these studies 

differ in key aspects from cuhent guidelines, and are therefore considered supplemental. 

However, these studies do iJdicate that PHMB is resistant to microbial attack in activated sludge. 

For down-the-drain or discharge to waste treatment plants the Agency will assume PHMB is 

stable based on this data. If :there is more current activated sludge test data that would change 

this value, such data can be ubmitted for review. 

An activated sludge espiration rate test was also conducted in the late 1970's 

(Acc#234289). As with the activated sludge studies, the protocols for this study differ from 

current practices for an acti ated sludge respiration inhibition (ASRI) study and therefore 

provide supplemental information. However, the information from the study is sufficient for use 

in the assessment and no nef testing is required at this time. The study demonstrated that at 

concentrations of 40 mg/L and higher the sludge process is affected such that respiration is 

affected and pH becomes more basic (7 .5 - 8.0). This latter effect can lead to inhibition of 

Page 9 of25 
nitrification and accumulation of suspended solids. Depending on the concentration of 

suspended solids a significant portion of the PHMB can potentiall be discharged to surface 

waters. No effect was observed on anaerobic sludge digestion froJ 56 to 250 mg/L. 

More recent literature studies by O'Malley et al. (2006, 2007) have shown that PHMB 

does biodegrade in the presence of certain microbes. However, th degradation is slow and even 

after 60 days, the degradation amounted only to 29%. 

Water Quality 

PHMB is not identified as a cause of impairment for any water bodies listed as impaired 

under section 303(d) of the Clean Water Act, based on informatio pro ided at the Agency's 

National Pesticides Cause oflmpairment of Waters website (searc ed AprillO, 2011)4

. In 

addition, no Total Maximum Daily Loads (TMDL) have been dev loped for PHMB, based on 

information provided at the Agency's National Pesticide TMDL b site (searched AprillO, 

2011 )

5

. More information on impaired water bodies and TMD Ls dm be found at 

http://www.epa.gov/owow/tmdl/. The Agency invites submission 6f water quality data for this 

pesticide. To the extent possible, data should conform to the qualitkr standards in Appendix A of 

the OPP Standard Operating Procedure: Inclusion of Impaired Wdter Body and Other Water 

Quality Data in OPP's Registration Review Risk Assessment and Management Process (see: 

http://www.epa.gov/oppfead1/cb/ppdc/2006/november06/session1-4sop.pdf ), in order to ensure 

they can be used quantitatively or qualitatively in pesticide risk assbsments. 

Drinking Water Assessment 

No drinking water exposure assessment has been performe for PHMB antimicrobial 

uses in previous assessments. The Agency does not anticipate the eed to perform a drinking 

water exposure assessment for PHMB uses as part of the registrati9n review assessment. While 

PHMB uses may result in discharges to surface waters, PHMB is expec ed to be removed from 

water either attaching to sediment and humic acid in the environmeht or removed during water 

treatment and therefore presence of this substance in drinking watefis not considered likely. 

4 . http://iaspub.epa.gov/tmdl waters I 0/attains nation cy.cause detail 303d?p cause group id=885 

5 

http://iaspub.epa.gov/tmdl waters I 0/attains nation.tmdl pollutant detail?p pollutant group id=885&p pollutant 

group name=PESTICIDES 

Page 10 of 25 
C. Ecological Effects Summary 

A summary of submitted ecological effects data for various PHMB polymer dispersions 

is provided in Table 3. There is no major degradate of concern. PHMB polymer dispersions 

tested to date demonstrate low toxicity to birds and mammals and high toxicity to freshwater 

invertebrates and very high toxicity to fish. All submitted ecological toxicity studies were 

conducted with a 20% a.i. solution of PHMB, which is the technical formulation, and values 

were adjusted to 100% a.i. to classify the studies according to relative toxicity. Limited 

additional data was found using EPA's ECOTOX database. In the registration review a 

quantitative ecological risk assessment will be conducted for use patterns which result in 

discharges ofPHMB to aquatic systems (e.g. cooling towers, paper mills, consumer products, oil 

well development uses). UsJ patterns such as cooling towers and consumer products will result 

in continuous, chronic exposfre of aquatic organisms and such exposures can occur in both 

freshwater and estuarine/ma]ine waters. 

As different technica grade PHMB products contain a mixture of polymers of differing 

chain length and distribution! toxicity is expected to potentially differ between the 20% PHMB 

(historic test substance) containing lower molecular weight polymer dispersions of PHMB as 

compared to higher molecular weight polymer dispersions of PHMB (20% and 96.3% PHMB 

technicals). Essentially all ofthe effects studies have been conducted with Vantocil IB, Vantocil 

P, and Baquacil which are 2Q% products containing lower molecular weight polymer chains of 

PHMB (characterization information oftest substance is average of n=4.5 to 5.5 mers). The 

96.3% PHMB is characterizJd as having a distribution containing higher molecular weight chain 

polymers with an average of 12 mers. Information bridging the toxicity of these distributions 

with chain length has not been provided, so there is uncertainty in the effects characteristics of 

the longer chain polymers. 

Table 3. Summary of Submitted Ecological Effects Toxicity Data for PHMB 

Study Type/ Tes~ MRID/ 

GLN (equivalent 850 Substance Species Endpoints Study Status/ 

GLN)/ Toxicity 

Study conditions (% PHMB) Classification! 

']ferrestrial Animal Acute and Chronic Toxicity 

BaquJcil Mallard duck LD50: > 502 mg a.i./kg-bw MRID 00027491/ Acute-Avian Oral/ 

Tec,cal (Anas (> 2510 mg t.s./kg-bw) Acceptable/ 71-1 (850.2100)/ platyrhnchos), (20 i) 20 weeks old, N=10 (no mortality) At most slightly toxic 

Northern bobwhite LC50: > 1124 ppm a.i. MRIDs 00041382 and 

(C. virginianus), (> 5620 ppm t.s.) 93191002/ 

Baqu~cil 14 days old, 23 Acceptable/ 

Acute- Avian Dietary/ Techn cal grams, N=10 (no treatment related mortality) At most slightly toxic 

71-2 (850.2200)/ (20 ) Mallard duck LCso> 1124 ppm a.i. MRID 00027492/ (A. platyrhnchos), (>5620 ppm t.s) Acceptable/ 14 days old, 226 At most slightly toxic 

grams, N=50 (no mortality) 

Acute-Mammalian Technical Laboratory rat MRID 00030220/ Oral/ Vantooil P LD50: 2747 mg a.i./kg-bw 

870.1100 (20.2%) (Rattus norvegicus) Slightly toxic 

Page 11 of25 
I I 

Study Type/ Test MRID/ 

GLN (equivalent 850 Substance Species Endpoints Study Status/ 

GLN)/ Toxicity 

Study conditions (% PHMB) Classification! 

Chronic- Mammalian Parental/Systemia NOAEL I 

Reproduction and LOAEL 

Fertility Effects/ Technical Laboratory rat 60012000 mg a.t./kg-diet MRID 436174011 

870.3800 Vantocil P ~ 69.6 I 238.9 g/kg bw; NA/ 

(20.2%) (Rattus norvegicus) ~ 71.3 I 270.5 rrg/kg-bw) Acceptable 

Reproductive and OffsP,ring 

NOAEL: >2000 m a.i.Mg-diet 

Freshwater Aquatic Animal Acute and Chronic Toxicity 

Acute- Freshwater Fish/ Technical Rainbow trout 

96-lrr LC,: 0.025f ppm a.i. 

72-1 (850.1075)/ Vantocil P (Oncorhynchus MRID 43949001/ 

(20%) + Acceptable 

flow-through 14C-PHMB my kiss) (measure ) Very highly toxic 

(26%) 2.21 grams, 53 mm 

r 

Acute- Freshwater Fish/ Baquacil Rainbow trout 

96-hr LC50: 0.11lppm a.i. 

MRID 111368 Test# 

72-1 (850.1075)/ Technical (Oncorhynchus 2746/ 

(20%) my kiss) (measure ) Supplemental/ 

static 0.46 grams Very highly toxic 

Acute- Freshwater Fish/ Technical Rainbow trout 96-hr LCso: 0.88 lmg a.i.IL MRID 00074296/ 72-1 (850.1075)/ Vantocil P (0. mykiss), (4.4 mg t.s.IL) SupplementalJ./ 

flow-through (20%) 3.9 g, 64mm (nominal/ mea ured~ Highly toxic 

Acute- Freshwater Fish/ Formulation Rainbow trout 96-hr LC50: 2.44 mg a.i./L MRID 00077928/ 72-1 (850.1075)/ Vantocil IB (0. mykiss), (12.2 mgt. ./L) Supplemental~/ 

flow-through (20%) 16.4 g, 10.5 em (nomina J Moderately toxic 

Acute- Freshwater Fish! Formulation Bluegill sunfish 96-hr LC50: 0.11 g a.i.IL MRID 42722101 with 72-1 (850.1075)/ Vantocil IB (L. macrochirus), (0.57 mg t.s.IL) addendum 437597011 

flow-through (20%) 1.18 g, 38 mm (nominal/measur d stock) Unacceptable/ 

Acute- Freshwater Fish! 96-hr LC50: 0.13 fllg a.i./L MRID 00077929 72-1 (850.1075)/ Formulation Bluegill sunfish (0.67 mg t.s ./L) (Ace# 234289)/ Vantocil IB (L. macrochirus), (nominal Unacceptable (low Static (20%) 0.39 g, 64mm 

Probit slope: IJ.714 DO) 

Acute-Freshwater Fish/ Technical Bluegill sunfish 96-hrLC50: 0.18 lrtg a.i./L MRID 00074295/ 72-1 (850.1 075)/ Vantocil P (L. macrochirus), (0.91 mg t.s ./L) Supplemental1/ 

Static (20%) 0.44 grams, 34 mm (nominal 11 

Highly toxic 

Acute- Freshwater Fish! Baquacil Bluegill sunfish MRID 111368 Test # 

72-1 (850.1075)/ 96-hr LC50: 0.34 mg a.i./L 2745/ Technical (L. macrochirus), (measured) Supplemental/ 

static (20%) 0.53 g Very highly toxic 

Acute- Freshwater Fish/ Baquacil Bluegill sunfish 96-hr LC50: 0.44 fg a.i./L MRID 00111368 Test 

72-1 (850.1075)/ Technical (L. macrochirus), (2.2 mg t.s.IL) # 2469/ 

(20%) 0.76 g (nominal)-chemic I samples Supplemental/ 

static awaiting analysis Very highly toxic 

Acute- Freshwater 48-hr EC50: 0.036 mg a.i./L MRID 00077929 Invertebrate/ Formulation Waterflea (0. 18 mg t.s.IL) (Ace# 234289)/ 72-2 (850.1010) Vantocil IB (Daphnia magna) (nominal~ 

20% a.i. <24 hours old I Supplemental/ 

Static Slope: 3.456 Very highly toxic 

Page 12 of 25 
Study Type/ Test MRID/ 

GLN (equivalent 850 Substance Species Endpoints Study Status/ 

GLN)/ Toxicity 

Study conditions (% PHMB) Classification1 

Acute- Freshwater MRID 416870-02 and Invertebrate/ Waterflea 48-hr EC50: 0.09 mg a.i./L 42149902/ 72-2 (850.1010) (Daphnia magna) (0.45 mg t.s.IL) Supplemental/ 

<24 hours old (nominal) Very highly toxic Static 

l· . . I ToxiCity category IS based on value expressed as the active mgred1ent. 

2

This study was conducted to pri arily observe time to death. There were two parts this experiment. One part 

consisted of a single exposu e level where 100% of exposed organisms died by 96 hours, which is not useable for 

the risk estimation models that wit be used in the risk assessment. The second component is classified as 

supplemental because sublethal e ects were not monitored, no treatment levels had partial kills, the particulate 

matter and organic carbon concen ation of the dilution water is not known, and the concentrations in exposure tanks 

were not analyzed. 

Joriginally the study was classifie~ as Acceptable, but a subsequent review reduced the classification to 

Supplemental. While the concen ations were measured and documented to be stable in stock solutions feeding the 

flow-through system, no measure ents were made in the test chambers. Additionally, the particulate matter and 

organic carbon concentration in thf water was not reported and is unknown. For this compound this is a critical 

parameter which can affect bioava lability and test results. 

1originally the study was classifieo as Acceptable, but a subsequent review reduced the classification to 

Supplemental because of low diss 1

Ived oxygen and no analytical confirmation of PHMB concentrations. 

Table 4. Summary of Pu~lic Ecological Effects Toxicity Data for PHMB 

Study Type/ Test GLN (equivalent 850 Substance Species Endpoints Citation GLN)/ 

Study conditions (% PHMB) 

Acute- Polychaete worm Estuarine/Marine Not 48-hr. LC50: 10.9 (Platynereis Hutchinson et al., 1995 Invertebrate reporter dumerilii) (95% CI 8.43 - 14.5) 

Non-guide! ine 

. . . . Tox1c1ty to Terrestnal AliJ/mals 

In order to estab ish re toxicity of PHMB to birds and conduct an ecological risk 

assessment for the registered antimicrobial use patterns of PHMB, the following tests are 

required using technical grade material: two avian acute oral (LD50) studies one with an 

upland game species and another with a waterfowl species (preferably the bobwhite quail 

and mallard duck, reSpectively) and one subacute avian dietary study (preferably with the 

bobwhite quail). There are two technical grade products for PHMB, one with a declared 

20% active ingredienlt content and one with a 96.3% active ingredient content. 

Submitted avian toxicity studies and their results are presented in Table 3. Acute oral 

testing with one aviaf species and subacute dietary testing with two avian species using 

the 20% PHMB tecllfical grade material has been conducted. Tests with the 96.3% 

PHMB technical grade material do not exist. The studies conducted using the 20% 

technical grade mate !ial were conducted as limit tests for the test substance rather than as 

Page 13 of 25 
the active ingredient, and therefore do not provide acceptable limit tests for the active 

ingredient (i.e., 502 mg a.i.lkg-bw versus 2000 mg a.i.lkg-bw for avian acute oral toxicity 

testing and 1124 mg a.i.lkg-diet versus 5000 mg a.i./kg-die for avian subacute dietary 

testing). Therefore, avian acute oral toxicity testing of the 20% TGAI with an upland 

game bird is still needed to evaluate risks and hazards from !industrial processes and water 

system antimicrobial use patterns and testing of the 96.3% TGAI with either an upland 

game bird or waterfowl species is still needed. Testing of e 96.3% TGAI with an 

upland game bird, either as a limit test (i.e., 2000 mg a.i.lkg-bw) or definitive test would 

provide PHMB information usable for both the 20% and 96.3% TGAI. 

PHMB technical grade material (20% active ingredient) is llassified as practically nontoxic to birds on a dietary basis (LC50 >5620 mg t.s.lkg-diet an~ for waterfowl on an 

acute oral basis (LD50 > 2510 mg t.s.lkg-bw). However, PHMB itself cannot be 

classified as practically non-toxic because the active ingred ent as not been tested up to 

the limit exposure concentration (LCso >5620 mg t.s.lkg-di t) or dose (LD50 > 2000 mg 

a.i.lkg-bw). 

Mammals 

Laboratory acute and reproductive mammalian toxicity dat discussed in the Human 

Health Assessment is used to assess hazards and risks to mammalian wildlife, the specific 

values that will be used to assess acute and reproductive effects to mammalian wildlife 

are summarized in Table 3. The acute oral LD50 for PHMBito rats was determined to be 

2757 mg a.i.lkg-bw (MRID 00030220) and the reproduction NOAEL was determined to 

be 600 mg a.i.lkg-diet based on parental systemic effects, ~ affect on reproduction was 

observed at the highest dietary concentration tested (2000 nig a.i.lkg-diet) (MRID 

43617401). Wild mammal testing is required on a case-by-dse basis, depending on the 

results of these lower tier mammalian studies, intended use hattem, pertinent 

environmental fate characteristics and exposure- the need fer such testing has not been 

identified at this time. 

Based on the acute oral rat data PHMB is classified as sligh ly toxic to mammalian 

wildlife. 

Toxicity to Freshwater Aquatic Animals 

Acute Effects 

In order to conduct a hazard and risk assessment for PHMB ito freshwater fish, the 

minimum data required is two acute toxicity tests: one warnt water and one cold water 

species. The preferable cold water species is rainbow trout and the preferable warm 

water species is the bluegill sunfish. Several acute toxicity ~ests for a warmwater fish, the 

bluegill sunfish (Lepomis macrochirus), and a coldwater fish, the rainbow trout using a 

I 

20% PHMB technical grade material of PHMB and a 20% PHMB formulation were 

submitted and reviewed by the Agency and are summarized in Table 3. Most of these 

were not acceptable for a variety of reasons, but one of the major issues that all of these 

studies had in common was the lack of analytical confirmation of the PHMB exposure 

concentration of PHMB throughout the duration of the study. PHMB can sorb to a 

Page 14 of 25 
variety of materials reducing the exposure concentration such that any results based on 

nominal concentrations or on stock concentrations alone rather than in test chamber 

analytical results may overestimate the exposure concentration, resulting in an 

underestimation of the toxicity of PHMB. Additionally, analytical results from several 

studies conducted under static conditions demonstrated that PHMB exposure 

concentrations were not stable under static conditions. There is one acceptable acute 

freshwater fish study with rainbow trout which was conducted under flow through 

conditions and the concentration of PHMB was measured in test chambers. The 96-h 

LC50 of 0.0254 ppm a.i. (MRID 43949001) from this study results in PHMB being 

classified as very highly toxic to freshwater fish. None of the blue gill studies provided 

acceptable test results. There were bluegill studies that have been previously identified as 

acceptable but these were either conducted as static studies and analytical results from 

these or other studies have demonstrated that PHMB concentrations are not stable under 

such conditions. 

The data requirement for acute freshwater fish testing with PHMB with a warm water 

species is not fulfilletl. 

The minimal testing L quired establishing the acute toxicity of PHMB to freshwater 

invertebrates is a freshwater aquatic invertebrate toxicity test, preferably using first instar 

Daphnia magna or e rly instar amphipods, stoneflies, mayflies, or midges. There are two 

freshwater D. magna studies available but both studies provide only supplemental 

information. Studies were previously identified as acceptable but these studies were 

conducted under static conditions which have been demonstrated under similar study 

conditions to be unstable, therefore results from these studies are expected to 

underestimate toxicit/y. 

The data requiremen for acute freshwater fish testing with PHMB with a warm water 

species is not fulfillep. 

Chronic Effects 

No chronic data is a ailable for PHMB with freshwater fish. Because uses of PHMB will 

result in repeated or · n some cases continuous discharge of the antimicrobial to aquatic 

environment a fish early life stage test with PHMB is required. There should be an acute 

toxicity test using the same test substance available for the same species. The more 

sensitive species of the two tested, rainbow trout should be used in the early life stage 

test. The lower ~ier early life stage test rather than a higher tier fish full life cycle test is 

anticipated at this ti e because there is no indication at this time that effects on 

reproduction (e.g., fer,ilization, fecundity) would be more sensitive than estimates of 

chronic effects from the early life stage test. 

No chronic data is a ailable for PHMB with freshwater invertebrates. Because uses of 

PHMB will result in repeated discharge or continuous exposure of PHMB to the aquatic 

environment a life cycle test with PHMB is required. 

Page 15 of 25 
Toxicity to Estuarine and Marine Animals 

Acute Effects 1 

No toxicity data for estuarine/marine animals has been subnritted. For uses where the 

antimicrobial is expected to reach estuarine or marine envirf nments, one 

estuarine/marine acute fish toxicity study, one acute crustacran toxicity study, and one 

mollusk study are required. While labeling precludes use ~ this product in oil recovery 

systems in or, over or near marine and/or estuarine oil field~ there are a number of other 

industrial water and process systems in addition to oil recovfry systems that do not 

preclude the discharge of effluents or spent fluids to waste ater treatment plants which 

discharge to marine or estuarine waters. For example, there are cooling towers and paper 

mills that discharge to estuarine and marine waters. Additionall , there are a number of . 

domestic waste water treatment plants that discharge to esturrine or marine waters, such 

that use in household and consumer products can result in dfscharge of this chemical to 

estuarine and marine waters. Therefore estuarine/marine organism fish and invertebrate 

data is needed. 

A public literature se~ch cond~~ted for the. 2004 RED fo~n~ a study using ~e marine 

polychaete, Platynerezs dumerzlu. InformatiOn on the specific PHMB matenal tested and 

I 

whether results are reported in terms of the test material or HMB are not provided. This 

information therefore provides at most antidotal informatiorl. 

Chronic Effects 

No chronic toxicity data for estuarine/marine animals has b en submitted. For uses 

where the antimicrobial is expected to reach estuarine or makine environments, and 

chronic or repeated exposure conditions exist chronic data £r

1 

r a fish and aquatic 

invertebrate species are required. The Agency proposes usi g anJ acute-to-chronic ratio 

(ACR) approach to estimate these values rather than ask for the data at this time. This 

approach would be contingent upon receiving freshwater fis and aquatic invertebrate 

chronic data to allow calculation of ACR values for a fish d in ertebrate, and 

contingent upon receiving acute estuarine/marine fish and invertebrate data to which 

these ACR values would be applied. 

Toxicity to Aquatic Plants 

No algal toxicity data have been submitted for PHMB. For the ecological risk 

assessment, including an endangered species assessment for all uses, the Agency 

anticipates needing the algal toxicity data for PHMB with four species: a green alga, a 

freshwater diatom, a saltwater diatom, and a cyanobacterium. 

Vascular, Nonrooted 

No toxicity testing with an aquatic vascular Lemna sp. has been submitted for PHMB. 

One test with PHMB is required. 

Page 16 of 25 
Adverse Ecological Incidents 

There are no reported incidents in the Agency's Ecological Incident Information System 

(EllS) regarding PHMB. The absence of documented incidents does not necessarily mean that 

such incidents did not occur. 

E. Ecological Effects Risk Assessment 

An ecological risk assessment was not conducted previously on PHMB's use patterns 

described in this document. PHMB 's uses that have potential for environmental exposure are 

discharges from industrial pfcesses and water systems, specifically: use in pulp and papermill 

process water systems, cool" g towers, oil well development and process waters, residential, 

commercial, and institutiona consumer products (e.g., pools, spas, laundry detergent, cleaning 

products) and industrial uses with down-the-drain discharges. The Agency needs to conduct 

environmental fate and ~~c~!~ical risk assessments for uses that potentially pass through waste 

water treatment plants (w ';llPs) and may be discharged into terrestrial and aquatic 

environments. Discharge directly to the environment may also occur from swimming pool water 

being discharged directly to the ground or to storm drains. The Agency has not previously 

assessed the potential for environmental exposures from the discharge of treated swimming pool 

water. In most cases, pesticides used in pools for the purpose of disinfection are dissipated in the 

process of providing the peshcidal effect (e.g., chlorine-based treatments). However, for more 

persistent chemicals, such aJ PHMB, the Agency has determined that such an assessment should 

be included in the registration review assessment. Additionally given the persistence of PHMB, 

the Agency plans on evaluafng releases to the environment from architectural paints and 

coatings applied to facades and other exterior surfaces due to leaching and washoff from rain, 

building wash water or irrig~tion overspray contacting these surfaces. For this ecological risk 

assessment, including an endangered species assessment for all uses, the Agency anticipates 

needing the ecotoxicity data outlined on pages 14 to 16 of this document. 

The Agency has not onducted a quantitative ecological risk assessment for PHMB 

previously that supports a complete endangered species effects determination. The ecological 

risk assessment planned during registration review will allow the Agency to determine whether 

PHMB uses have "no effect or "may affect" federally listed threatened or endangered species 

(listed species) or their desi ned critical habitats. When an assessment concludes that a 

pesticide's use "may affect"ja listed species or its designated critical habitat, the Agency will 

consult with the U.S. Fish aljld Wildlife Service and/or National Marine Fisheries Services (the 

Services), as appropriate. 

Page 17 of25 
F. Environmental Fate and Ecotoxicity Data Gaps and Anticipated 

Work 

Down-the-drain environmental fate studies are supplemental studies and do not provide 

adequate information that can be used to ascertain a dose-response curve of the relationship 

between concentration of PHMB and respiration inhibition effects to activated sludge 

microorganisms. Although a quantitative assessment of risks to act vated sludge microorganisms 

is not currently within the scope of ecological risk assessments for 4ntimicrobial pesticides, 

consideration of potential adverse effects to wastewater treatment ant microorganisms is 

included. Therefore an Activated Sludge Respiration Inhibition (ASRI) test is required. While 

the aerobic and anaerobic metabolism studies are supplemental, the; · nformation from these 

studies is sufficient to identify PHMB as stable so no additional stu ies are required at this time. 

If there are more current studies that have been conducted the Age y recommends this 

information be submitted. The Agency anticipates needing the foll wing environmental fate 

study for each TGAI (i.e., 20% and 96.3% ): 

• Activated Sludge Sorption/Desorption- TGAI (OCSP 835.1110); and 

• Activated Sludge Respiration Inhibition (ASRI) test- TGAI (O:EjCD 209, OCSP 

850.3300). 

To be able to determine both acute and chronic risks to aqu tic organisms from 

discharges to both freshwater and estuarine/marine waters addition'll inf0rmation on toxicity of 

PHMB to aquatic plants and estuarine/marine organisms are needed. The Agency anticipates 

needing the following ecological effect studies for each TGAI (20~ and 96.3%). For aquatic 

organisms, if the 20% and 96.3% TGAI tests with acute freshwater rish, freshwater invertebrate, 

green algae, and whole sediment Hyallela azteca toxicity tests dem?nstrate that toxicity is 

bridgeable between the lower molecular weight and higher molecular weight polymer 

dispersions, the remaining effects tests are needed only for one of tHe TGAis. Additionally, if 

one of the dispersions is more toxic, the remaining tests can be con ucted with the more toxic 

form only. However in the latter case, the toxicity of the TGAI not ested will be assumed to be 

that of the more toxic TGAI for purposes of the risk assessment. 

• Avian Acute Oral Toxicity, Upland Game Species- TGAI (GI LN 850.2100 or OECD 

233); 

• Freshwater Invertebrate Acute Toxicity- TGAI (OCSPP 85 .1010); 

• Mollusk Shell Deposition Toxicity study or Mollusk Embryo Larvae Toxicity studyTGAI (OCSPP 850.1025 or OCSPP 850.1055, respectively) 

• Freshwater Fish Acute Toxicity, Warm Water Species- TGAI (OCSPP 850.1075); 

• Estuarine/Marine Fish Acute Toxicity study- TGAI (OCSPP 850.1075); 

• Freshwater Invertebrate Life Cycle study-TGAI (OCSPP 850.1300); 

• Freshwater Fish Early Life Stage study using the most acutely sensitive fish- TGAI 

(OCSPP 850.1400); 

• Estuarine/Marine Shrimp Acute Toxicity study using the saltwater mysid- TGAI 

(OCSPP 850.1035); 

Page 18 of 25 
• An Estuarine/Marine Shrimp Chronic Toxicity Test- TGAI (OCSPP 850.1350); 

• An Estuarine/Marine Fish Early Life Stage study- (OCSPP 850.1400); 

• Seedling Emergence and Growth Tier II for rice- TGAI (OCSPP 850.4100); 

• Aquatic vascular plant growth Tier II data for a Lemna sp.- TGAI (OCSPP 850.4400); 

• Algal toxicity Tier II data for a green alga species- TGAI (OCSPP 850.4500); 

• Algal toxicity Tier II data for a freshwater diatom species- TGAI (OCSPP 850.4500); 

• Algal toxicity Tier III data for a marine diatom specie- TGAI (OCSPP 850.4500); 

• Algal toxicity Tier II data for a cyanobacterium species- TGAI (OCSPP 850.4550); 

• Chronic Whole Sedi ent Freshwater Invertebrate Toxicity Test with the amphipod 

Hyallela azteca- T1 AI (Special Study); 

• Chronic Whole edi ent Freshwater Invertebrate Toxicity Test with the midge 

(Chironomous sp.)- ITGAI (Special Study); and 

• Chronic Whole edi1jllent Estuarine/Marine Invertebrate Toxicity Test with the amphipod 

Leptochirus plumulosus)- TGAI (Special Study). 

For the least acutely sensitivf estuarine/marine species a chronic value may potentially be 

estimated using an acute-to-chronic ratio (ACR) approach. If the ACR derived from the 

estuarine/marine chronic test conducted for the more sensitive estuarine/marine organism (based 

on the acute results) does not differ from ACRs calculated from freshwater species, the chronic 

test for the less sensitive organism may be estimated using existing ACRs and the acute value for 

the less sensitive species. F om the Office of Water (OW) guidance ACRs within a factor of ten 

are considered not to differ significantll. 

Also, please note that on Juj e 27, 2012, EPA announced certain revisions in harmonized 

guideline series 850 - Ecological Effects Tests - including removal of the Tier designation on 

850.4100 (Seedling Emergeiilce and Seedling Growth), 850.4400 (Aquatic Plant Toxicity Test 

Using Lemna Spp.), 850.44SO (Aquatic Plants Field Study) and 850.5400 (Algal Toxicity). For 

more information see "FinaliTest Guidelines; OCSPP 850 Series; Notice of Availability" 77 FR 

38282,June27,20127

. 

• The Algal Toxicity s udy (Public Draft OPPTS 850.5400) was replaced by the following 

harmonized guidelines: OCSPP 850.4500: Algal Toxicity and OCSPP 850.4550 

Cyanobacteria (AnaUaenaflos-aquae) Toxicity; 

• The Seedling Emergynce and Growth, Tier II study (Public Draft OPPTS 850.4225) was 

replaced by the following harmonized guideline: OCSPP 850.4100: Seedling Emergence 

and Seedling Growth; and 

• The Modified ASRI lest (Public Draft OPPTS 850.6800) was renumbered OCSPP 

850.3300). 

6 http://water.epa.gov/scitech/swguidance/standards/criteria/aglife/upload/85guidelines.pdf 

7 http:/ /www.regulations.gov/#!dot umentDetail ;D=EP A-HQ-2009-0154-0028 

Page 19 of 25 
The OPP, the ORD and the OW are actively working on deriving a common effects 

characterization methodology for use in ecological assessments of hemicals by EPA to meet the 

mandates of the Clean Water Act (CWA) and the Federal Insecticide, Fungicide, and 

Rodenticide Act (FIFRA). Currently the Agency does not have a fixed timeframe for this effort 

but are actively working with OW and ORD on follow-up actions that will advance harmonized 

methodologies. The Agency's web page8 on harmonization of co mon effects will be updated 

as the effort progresses. 

Additional Data Needs 

Facility Emissions to WWTP Modeling 

For assessing the fate of PHMB to receiving waters from inl::l.ustrial process water uses of 

PHMB such as at pulp and paper mills, for recirculating codling towers, and oil well 

development the Agency anticipates using the available en liroruhental fate information 

from guideline studies for PHMB and the following emission scdnarios. 

• To estimate exposure related to releases of PHMB to do estic wastewater treatment 

plants from uses such as PHMB in detergents, laundry nnses and cleaners the 

Agency will rely on the Office of Chemical Safety and *ollufion Prevention (OCSPP) 

model, Exposure and Fate Assessment Screening Tool (E-FAST, version 2.0, 2007, 

or EFAST2). From this model, the Agency will use the 'Do'Yn-the-Drain" (DtD) 

module, which is designed to evaluate releases to dome tic wastewater treatment 

plants. It is suitable for all the indoor sources of PHMB that could potentially be 

exposed through a consumer "down-the-drain" scenario The model provides 

screening level estimate concentrations of chemicals in . urface water that may result 

from household uses and the disposal of consumer prod cts into wastewater using a 

few simple input parameters (production volume and fraction of the chemical 

removed during wastewater treatment). 

• 

• 

• 

Potential environmental releases and associated exposu!s of concern for 

antimicrobial uses related to the Pulp, Paper, and Board Industry will be those 

identified in "Emission Scenario Documents on Pulp, P per, and Board Industry", 

Number 23 of OECD Series on Emission Scenario Doc ments dated July 8, 2009. 

Potential environmental releases and associated exposu+s of concern for 

antimicrobial uses related to the Oil and Gas Well Prod~ction Industry will be those 

identified in the latest version of the OECD Emission SGenario Document for the Oil 

Well Production Industry or those identified in the lates~ version of Generic Scenarios 

developed by the Chemical Engineering Branch of EPA(OCSPP/OPPT/CEB 

(Chemical Engineering Branch). On-shore operations sume potential for disposal 

of drilling fluids and produce water to public or industrial waste treatment facilities 

and off-shore operations assume emissions directly to the surrounding water, posttreatment for removal of oil. I 

Potential environmental releases and associated exposures of concern for uses of 

antimicrobial uses related to recirculating cooling towers will be assessed using the 

Generic Scenarios for recirculating cooling towers developed by the Chemical 

8 www.epa.gov/oppefed I /cwa fifra effects methodology/scope.html 

Page 20 of25 
Engineering Branch of EP A/OCSPP/OPPT/CEB and modified for use for 

antimicrobials by the Antimicrobial Division. 

• Potential environmental releases and associated exposures of concern for 

antimicrobial uses related to adhesive preservatives will be those identified in 

"Emission Scenario Document on Adhesive Formulation", Number 20 of OECD 

Series on Emission Scenario Documents dated April24, 2009; 

• Potential environmental releases and associated exposures of concern for 

antimicrobial uses related to paints and coating preservatives will be those identified 

in "Emission Scenario Document on Coating Industry (Paints, Laquers and 

Varnishes)", Number 22 of OECD Series on Emission Scenario Documents dated 

April 24, 2009; and 

Facility information eeded to estimate aquatic exposures from emissions to WWTP for 

each emission scenarro and directly to water include the following: 

• The number of pt lp and paper mill sites using PHMB or the maximum annual 

pro?uc~ion volm e of PHMB used in pulp and paper mills in the United States and its 

terntones; 

• The number of circulating cooling tower sites using PHMB or the maximum annual 

pro?uc~ion volu, e of PHMB used in cooling towers in the United States and its 

terrttones; 

• The number of o·l well development sites using PHMB or the maximum annual 

production voluiY,e of PHMB used in oil and gas well development in the United 

States and its te, itories; 

• The number of adhesive industrial or manufacturing sites using PHMB or the 

maximum annual production volume of PHMB used in the adhesive formulation 

industry in the United States and its territories; 

• How many of eaa:h of these facilities has on-site and/or off-site wastewater treatment. 

In the absence of infl rmation on the number of these facilities that use PHMB and how 

many of these facilides have on-site and/or off-site wastewater treatment, the Agency 

will assume that all ch facilities in the United States have the potential to use PHMB. 

During the public coL entJ'"riod on the Preliminary Work Plan, the Bay Area Clean 

Water Agencies (B~CWA) and the California Stormwater Quality Association 

(CASQA)10 provided informational materials on the number of pools in existence 

nationally and withirl California, swimming pool discharge practices from local agencies 

from around the cou try, and a swimming pool discharge study. This information will be 

reviewed and where appropriate used to assist EPA with development of a modeling 

scenario for swimmihg pools. 

9 In the docket as EPA-HQ-OPP-2012-0341-007 10 In the docket as EPA-HQ-OPP-Q012-0341 -009 

Page 21 of 25 
References 

de Paula, G. F., G. I. Netto, and L.H.C. Mattoso. 2011. Physical a*d chemical characterization 

of poly(hexamethylene biguanide) hydrochloride. Polymers 13:928-941. 

Kaehn, K. 2010. Polihexanide: a safe and highly effective biguanioe. Skin Pharmacology and 

Physiology 223(1):7-16. 

O'Malley, L.P., A.N. Collins, and G.F. White. 2006. Biodegradability of end-groups of the 

biocide biguanide (PHMB) assessed using model compound 1

. Journal of Industrial 

Microbiology and Biotechnology 33:677-684. 

Page 22 of25 
Appendix A: Ecological Guideline Special Study Justifications 

Study Title: Chronic Freshwater Whole Sediment Toxicity Test using the amphipod 

Hyalella azteca 

Guideline Number: Special Study, Use Agency-wide guideline Test Method 100.4: Hyalella 

azteca 42-d Test for Measuring the Effects of Sediment Associated Contaminants on 

Survival, Growth, and Reproduction in USEP A 2000 Methods for Measuring the 

Toxicity and Bioaccumulation of Sediment-associated Contaminants with Freshwater 

Invertebrates EPA 600/R-99/064 

Exposure Method: Spiked whole sediment 

Test Substance: TGAI 

Rationale for Requiring the Data 

No chronic spiked-sedimentjtoxicity test for a freshwater benthic amphipod has been submitted 

for PHMB. A number of use patterns of PHMB such as industrial processes and water systems, 

oil and gas well production ystems, and consumer products may result in PHMB reaching 

aquatic freshwater sediment through discharge to waste water plants and subsequent discharge 

to surface waters. PHMB is expected to sorb to organic and inorganic material which would be 

associated primarily wifh the sediment in the environment. Sediment benthos may be exposed 

chemicals in the sediment vik pathways not accounted for in water only studies, such as ingestion 

of sediment. Chemicals tha partition to sediment and are persistent in the sediment have the 

potential to pose a chronic risk to sediment benthos. PHMB is highly stable in the environment 

and is not expected to readily degrade from the sediment and therefore uses and environmental 

fate pose a potential chronic 1

risk to estuarine/marine sediment benthos. 

Prior to conduct of the stud , the test design and protocol must be submitted for Agency review 

and approval. The preferred1 

sediment is formulated, guidance for the formulated sediment can 

be found in OECD 218 Sediment-Water Chironomid Toxicity Test using Spiked Sediment. 

Based on test variabilit for the endpoints of concern (includes reproduction) and the need to 

establish a NOAEC/LOAEd the following number of replicates and test animals are 

recommended for this test: 1lireplicates per treatment ( 4 for 28-d survival and growth and 8 for 

the remainder of the test) wi~ 10 neonates per replicate. For alternative test designs the protocol 

should discuss the power of Jlle test. 

Practical Utility of the Data 

1. How will the data be use'd? 

Data from sediment toxicity studies will be used to estimate potential chronic risks to freshwater 

benthic organisms associate . with uses of PHMB. Data from sediment toxicity studies will be 

compared to estimated sedillllent chronic exposure concentrations to evaluate the potential for 

PHMB to adversely impact Jurvival, reproduction, and growth of sediment invertebrates. 

2. How could the data impL t the Agency's future decision-making? 

If the data indicates that regJ"stered PHMB usage may pose a risk of adverse effects to non-target 

benthic organisms aboVie th Agency Level of Concern, the Agency may explore decision 

options to mitigate this risk. The lack of these data will limit the flexibility the Agency and 

registrants have in coming i to compliance with the Endangered Species Act, and could result in 

use restrictions for PHMB J hich may otherwise be avoided, or which are unnecessarily severe. 

Page 23 of25 
Study Title: Chronic Freshwater Whole Sediment Toxicity Test using a midge, Chironomus 

sp. 

Guideline Number: Special Study, Use Agency-wide guideline Test Method 100.5: Lifecycle Test for Measuring the Effects of Sediment-Associated Contaminants on 

Chironomus dilutus or C. tentans in USEPA 2000 Methods for Measuring the Toxicity 

and Bioaccumulation of Sediment-associated Contaminants with Freshwater 

Invertebrates EPA 600/R-99/064 

Exposure Method: Spiked whole sediment 

Test Substance: TGAI 

Rationale for Requirin2 the Data 

No chronic spiked-sediment toxicity test for a freshwater benthic rrydge as been submitted for 

PHMB. A number of use patterns of PHMB such as industrial processes and water systems, oil 

and gas well production systems, and consumer products may resul in PHMB reaching aquatic 

freshwater sediments through discharge to waste water plants and spbsequent discharge to 

surface waters. PHMB is expected to sorb to organic and inorgani material which would be 

associated primarily with the sediment in the environment. Sedime t benthos may be exposed 

chemicals in the sediment via pathways not accounted for in water only studies, such as ingestion 

of sediment. Chemicals that partition to sediment and are persisten in the sediment have the 

potential to pose a chronic risk to sediment benthos. PHMB is higHly stable in the environment 

and is not expected to readily degrade from the sediment and there ore uses and environmental 

fate pose a potential chronic risk to estuarine/marine sediment bentllos. 

Prior to conduct of the study, the test design and protocol must be shbmitted for Agency review 

and approval. The preferred sediment is formulated, guidance for e formulated sediment can 

be found in OECD 218 Sediment-Water Chironomid Toxicity Testr sing Spiked Sediment. 

Based on test variability for the endpoints of concern (includes reprpduction) and the need to 

establish a NOAEC/LOAEC the following number of replicates and test animals are 

recommended for this test: for the midge test with C. dilutus 16 rept,icat9s containing 12 test 

organisms each (12 replicates at test initiation; 4 added at 10 days :D ' r auxiliary males). For 

alternative test designs the protocol should discuss the power of the test. I 

Practical Utility of the Data 

1. How will the data be used? I 

Data from sediment toxicity studies will be used to estimate potential chronic risks to freshwater 

benthic organisms associated with uses of PHMB. Data from sedi0 ent toxicity studies will be 

compared to estimated sediment chronic exposure concentrations to evaluate the potential for 

PHMB to adversely impact survival, reproduction, and growth of sediment invertebrates. 

2. How could the data impact the Agency's future decision-mak'ng? 

If the data indicates that registered PHMB usage may pose a risk ofj adverse effects to non-target 

benthic organisms above the Agency Level of Concern, the Agenc~ may explore decision 

options to mitigate this risk. The lack of these data will limit the flexibility the Agency and 

registrants have in coming into compliance with the Endangered Spbcies Act, and could result in 

use restrictions for PHMB which may otherwise be avoided, or which are unnecessarily severe. 

Page 24 of25 
Study Title: Chronic Marine/Estuarine Whole Sediment Toxicity Test using Leptocheirus 

plumulosus 

Guideline Number: Special Study, Use Agency-wide guideline Methods for Assessing the 

Chronic Toxicity of Marine and Estuarine Sediment-Associated Contaminants with the 

Amphipod Leptocheirus plumulosus (USEPA 2001c) 

Exposure Method: Spiked whole sediment 

Test Substance: TGAI 

Rationale for Requiring the Data 

No chronic spiked-sedimentltoxicity test for an estuarine/marine benthic amphipod has been 

submitted for PHMB. A nmr,ber of use patterns of PHMB such as industrial processes and water 

systems, oil and gas well pr9duction systems, and consumer products may result in PHMB 

reaching aquatic estuar ne~5~rine sediments through discharge to waste water plants and 

subsequent discharge to s~~ ce waters. PHMB is expected to sorb to organic and inorganic 

material which would be as~siated primarily with the sediment in the environment. Sediment 

benthos may be exposed ch icals in the sediment via pathways not accounted for in water only 

studies, such as ingestion of sediment. Chemicals that partition to sediment and are persistent in 

the sediment have the poten ial to pose a chronic risk to sediment benthos. PHMB is highly 

stable in the environment anti is not expected to readily degrade from the sediment and therefore 

uses and environmental fate pose a potential chronic risk to estuarine/marine sediment benthos. 

Prior to conduct of the study, the test design and protocol must be submitted for Agency review 

and approval. The preferre~ sediment is formulated, guidance for the formulated sediment can 

be found in OECD 218 Sediment-Water Chironomid Toxicity Test using Spiked Sediment. 

Based on test variability for the endpoints of concern (includes reproduction) and the need to 

establish a NOAEC/LOAE the following number of replicates and test animals are 

recommended for this test: 10 replicates per treatment with 20 neonates per replicate. For 

alternative test designs the otocol should discuss the power of the test. 

Practical Utility of the Data 

1. How will the data be used? 

Data from sediment toxicitylstudies will be used to estimate potential chronic risks. to 

estuarine/marine benthic oq anisms associated with uses of PHMB. Data from sediment toxicity 

studies will be compared to estimated sediment chronic exposure concentrations to evaluate the 

potential for PHMB to adve 1

sely impact survival, reproduction, and growth of sediment 

invertebrates. 

2. How could the data impact the Agency's future decision-making? 

If the data indicates tha reg.lstered PHMB usage may pose a risk of adverse effects to non-target 

benthic organisms above the Agency Level of Concern, the Agency may explore decision 

options to mitigate this risk. I The lack of these data will limit the flexibility the Agency and 

registrants have in coming iljltO compliance with the Endangered Species Act, and could result in 

use restrictions for PHMB which may otherwise be avoided, or which are unnecessarily severe. 

Page 25 of25