# PBT Assessment of Hydraulic Fracturing Fluids from Coal Seam Gas Fields in Australia

# • Joint venture partners expanding coal seam gas (CSG) fields in the Bowen Basins of Queensland

• A hydraulic fracturing quantitative risk assessment (QRA) is required as part of the Environmental Impact Statement (EIS) approval process

• The QRA evaluates the chemicals used in the stimulation (hydraulic fracturing) event to determine management measures to prevent potential risks to human health and the environment

• The science and fluids used in hydraulic fracturing are constantly evolving

• Based on geologic and hydraulic conditions in the coal seam formation, a broad mixture and variety of constituents are used 

# Introduction

# Introduction

# Introduction

# Overall QRA Approach

# • Evaluation and ranking of the relative hazards of hydraulic fracturing chemicals to identify the constituents that warrant detailed evaluation in QRA

• Lack of regulatory risk

- based screening criteria for hydraulic fracturing chemicals

• An assessment of persistence, bioaccumulation, and toxicity (PBT) is a tool for evaluating the constituents that are potentially a concern to human health or the environment based on:

• Degrade or dissociate in the environment

• Bioaccumulate in terrestrial or aquatic species

• Exert toxic effect on human health or ecological receptors



# • PBT information compiled in toxicological and environmental profile Hazard Assessment

# • Assessment of hazard and not potential risk

• QRA compares exposure levels of a hydraulic fracturing chemical by receptor to a maximum acceptable level without significant adverse effect



# • PBT assessment does not consider exposure concentrations for most of the hydraulic fracturing chemicals

• Defines which hydraulic fracturing fluids may potentially present a risk

• If a threshold concentration is present based on the toxicity demonstrated in the PBT assessment

• The persistence and bioaccumulation that facilitates their potential for exposure by human and ecological receptors. 

# PBT Assessment

# • Conducted using PBT Assessment guidance from Australia or the European Union’s Registration, Evaluation, Authorisation and Restriction of Chemicals (REACH) program

• One of the challenges in compiling the necessary PBT data is the proprietary nature of the constituents in the hydraulic fracturing fluids

• There may be limited robust experimental data available to assess PBT



# • For constituents where the relevant data may not be available, appropriate modeling software may be used to obtain the data (i.e. US EPA EPISUITETM

- Estimation Programs Interface SuiteTM). PBT Assessment

# • Chemical Risk Information Platform (CHRIP) [Japan] Information on Biodegradation and Bioconcentration of the Existing Chemical Substances Database http://www.safe.nite.go.jp/english/db.html

• European Chemical Agency (ECHA) public database of Registration, Evaluation, Authorization and Restriction of Chemical Substances (REACH). registered substances (ECHA CHEM) http://apps.echa.europa.eu/registered/registered

- sub.aspx

• U.S. Environmental Protection Agency (USEPA) High Production Volume Information System (HPVIS) http://www.epa.gov/chemrtk/hpvis/index.html

• New Zealand Environmental Protection Authority

- New Zealand Hazardous Substances and New Organisms (HSNO) Chemical Classification Information Database (CCID) http://www.epa.govt.nz/search

- databases/Pages/HSNO

- CCID.aspx

• World Health Organization (WHO) International Programme on Chemical Safety (IPCS) Chemical Safety Information from Intergovernmental Organizations (INCHEM) http://www.inchem.org/

• Australian National Industrial Chemicals Notification and Assessment Scheme (NICNAS) Priority Existing Chemical (PEC) Assessment Reports http://www.nicnas.gov.au/Publications/CAR/PEC.asp

• OECD Screening Information Dataset (SIDS) Database OECD Existing Chemicals Screening Information Data Sets (SIDS) Database (in IUCLID software) http://oecdsids.jrc.ec.europa.eu:80/i5browser/Welcome.do

• OECD Initial Assessment Reports for HPV Chemicals including Screening Information Data Sets (SIDS) as maintained by United Nations Environment Programme (UNEP) Chemicals http://www.chem.unep.ch/irptc/sids/OECDSIDS/sidspub.html 

# Sources of PBT Data

# US EPA EPISUITETM

# US EPA EPISUITETM

# US EPA EPISUITETM

# • The results of BIOWIN v4.10 for THPS are as follows: biodegrade fast (Biowin2); ultimate biodegradation timeframe is days

- weeks (Biowin3); and biodegrades fast (Biowin 6)

• THPS does not meet the screening criteria for persistence.



# • The estimated log Kow for THPS using EPISUITE is

- 20.39. Hydrolysis is also indicated as a significant abiotic degradation process

• THPS does not meet the screening criteria for bioaccumulation.



# • The NOEC from a 72

- hr green algae study was reported to be 0.063 mg/L, which is <0.01 mg/L

• THPS meets the criteria for toxicity.



# • The overall conclusion is that THPS is not a PBT substance PBT Profile: Tetrakis(hydroxymethyl) phosphonium sulfate (THPS)

# Australia PBT Criteria

Criterion PBT criteria

Persistence For PBT purposes a chemical is considered persistent in a particular media if its half

- life in the media exceeds the following: Half life (T 1/2 ) >2 months in water Half life (T 1/2 ) >6 months in soil Half life (T 1/2 ) >6 months in sediment
Half l ife (T 1/2 ) >2 days in air

Bioaccumulative For PBT purposes a chemical is considered to be bioaccumulative if it has a BCF/BAF of >2000, or in its absence of any BCF/BAF measurement a log K ow >4.2.

Toxic For PBT purposes, in respect of aquatic toxicity, a chemical may be considered toxic under the following circumstances (corresponding to criteria for GHS chronic category 1:

Non

- rapidly degradable substances for which there are adequate chronic toxicity data available Chronic NOEC or EC x (for fish) <0.1 mg/L and/or

Chronic NOEC or EC x (for crustacea) <0.1 mg/L and/or

Chronic NOEC or EC x (for algae or other aquatic plants) <0.1 mg/L

Rapidly degradable substances for which adequate chronic toxicity data are available Chronic NOEC or EC x (for fish) <0.01 mg/L and/or

Chronic NOEC or EC x (for crustacea) <0.01 mg/L and/or

Chronic NOEC or EC x (for algae or other aquatic plants) <0.01 mg/L

Substances for which adequate chronic toxicity data are not available (providing criteria for P and B are met) 96 h LC 50 (for fish) <1 mg/L and/or

48 h EC 50 (for crustacea) <1 mg/L and/or

72 or 96 ErC 50 (for alage or other aquatic plants) <1 mg/L

And the substance is not rapidly degradable and/or the experimentally determined BCF is >500 (or, if absent, the log K ow is >4.2
Toxicity to other (terrestrial) organisms Should be considered on a case by cases basis, compared with the highly toxic classifications DotE has developed for ag/vet chemicals
Long term toxicity or evidence such as endocrine disruption effects Should be considered on a case

- by

- case basis.

# REACH PBT Criteria

Type of Dat a Criterion Screening Assignment

Persistence Ready biodegradability test Readily biodegradable Not P and not vP Enhanced ready biodegradability test Readily biodegradable Not P and not vP

Specified tests on inherent biodegradability

Zahn

- Wellens (OECD 302B) >70% mineralization (DOC removal) within 7 d; log phase no longer than 3 d; removal before degradation occurs below 15%; no
pre

- adapted inoculum Not P

MITI II test (OECD 302C) >70% mineralization (O 2 uptake) within 14 d; log phase no longer than 3 d; no pre

- adapted inoculum Not P

Biowin 2 (non

- linear model prediction) and Biowin 3 (ultimate biodegradation time)

or Does not biodegrade fast (probability) and ultimate biodegradation timeframe predicti on: >months (value <2.2)

or P

Biowin 6 (MITI non

- linear model prediction) and Biowin 3 (Ultimate biodegradation time) Does not biodegrade fast (probability <0.5) and ultimate biodegradation timeframe prediction: >months (value <2.2) P

Bioaccumulation Convincing evidence that a substance can biomagnify in the food chain (e.g., field data). e.g., BMF >1 B or vB, definitive assignment possible

Octanol

- water partition coefficient (experimentally derived or estimated by valid QSAR) Log K ow < 4.5 Not B and not vB

Toxicity

Short

- term toxicity aquatic toxicity (algae, daphnia, fish) EC 50 or LC 50 <0.01 mg/L T, criterion considered to be definitely fulfilled

Short

- term toxicity aquatic toxicity (algae, daphnia, fish) EC 50 or LC 50 <0.1 mg/L T

Avian toxicity (subchronic or chronic toxicity or toxic for reproduction) NOEC <30 mg/ kilogram( kg ) food T

# REACH PBT Criteria

# • A PBT Assessment was used to evaluate the potential for human health and environmental (e.g., ecological) risks by comparing a “green” fluid system to a previous water and guar based system that was assessed using the QRA process

• The results of the QRA indicated acceptable risks with implementation of operational and H&S management procedures, and spill containment procedures



# • The “green” fluid system was developed as a more environmentally fluid system than their original formulation, the composition is similar with substitutions for less hazardous chemicals

• For chemicals assessed in the “green” fluid system, none were considered to be inherently hazardous, and potential risks were no greater than original fluid system Comparison of Fluid Systems

# • Marcellus Shale Coalition develops guidance for the hydraulic fracturing operations within the Marcellus Shale

• A key consideration is the evaluation and assessment of current and proposed additives for the drilling and completion process

• One tool to use in this evaluation process could include the PBT Assessment

• Relatively quick and cost

- effective method to evaluate proposed substitutions or new fluid systems to be used

• Part of an educational source of tools and references to take into consideration to evaluate the selection of fluid additives and subsequent blends / formulations 

# Marcellus Shale Gas

# Questions