Risk Management Evaluation Endosulfan

Introduction

17.In June 2015, the European Union (EU) and its member States submitted a proposal to list pentadecafluorooctanoic acid (CAS No: 335-67-1, PFOA, perfluorooctanoic acid), its salts and
PFOA-related compounds in Annex A, B, and/or C of the Stockholm Convention (UNEP/POPS/POPRC.11/5). This proposal was considered by the Persistent Organic Pollutants Review Committee (POPRC) at its eleventh meeting held in October 2015, where the Committee concluded that PFOA fulfilled the screening criteria in Annex D and that issues related to the inclusion of PFOA-related compounds that potentially degrade to PFOA and the inclusion of PFOA salts should be addressed in the draft risk profile (see decision POPRC-11/4).

18.The substances covered by the risk profile are PFOA including its isomers, its salts and

PFOA-related compounds. At its twelfth meeting held in September 2016, by its decision
POPRC-12/2, the Committee adopted the risk profile (UNEP/POPS/POPRC.12/11/Add.2) and decided to establish an intersessional working group to prepare a risk management evaluation that includes an analysis of possible control measures for PFOA, its salts and PFOA-related compounds in accordance with Annex F to the Convention. Further, the Committee invited Parties and observers to submit to the Secretariat the information specified in Annex F before 9 December 2016.

19.Consistent with the risk profile, this risk management evaluation focuses on PFOA including isomers, its salts and PFOA-related compounds. This risk management evaluation is accompanied by a background document (UNEP/POPS/POPRC.13/INF/6), and to assist with the identification of

PFOA-related compounds a non-exhaustive list of substances covered or not covered by the risk management evaluation is also provided (UNEP/POPS/POPRC.13/INF/6/Add.1).

Chemical identity of PFOA, its salts and PFOA-related compounds

20.PFOA, its salts and PFOA-related compounds fall within a family of perfluoroalkyl and polyfluoroalkyl substances (PFASs). Perfluorinated acids, like PFOA, are not degradable in the environment and in biota (including humans). Certain polyfluorinated substances can be degraded to persistent perfluorinated substances like PFOA under environmental conditions and are therefore precursors. Those PFASs that can be degraded to PFOA in the environment and in biota are referred to as PFOA-related compounds.

21.The risk management evaluation covers:

1. 
   PFOA (pentadecafluorooctanoic acid, CAS No: 335-67-1, EC No: 206-397-9)including any of its branched isomers;
   
2. 
   Its salts; and
   
3. 
   PFOA-related compounds which, for the purposes of this risk management evaluation, are any substances that degrade to PFOA, including any substances (including salts and polymers) having a linear or branched perfluoroheptyl group with the moiety (C₇F₁₅)C as one of the structural elements, for example:
   

1. 
   Polymers with ≥C₈ based perfluoroalkyl side chains;²
   
2. 
   8:2 fluorotelomer compounds;
   
3. 
   10:2 fluorotelomer compounds.
   

The compounds below do not degrade to PFOA and are therefore not included as PFOA-related compounds:

1. 
   C₈F₁₇-X, where X= F, Cl, Br;
   
2. 
   Fluoropolymers³ that are covered by CF₃[CF₂]n-R’, where R’=any group, n>16;⁴
   
3. 
   Perfluoroalkyl carboxylic and phosphonic acids (including their salts, esters, halides and anhydrides) with ≥8 perfluorinated carbons;
   
4. 
   Perfluoroalkane sulfonic acids (including their salts, esters, halides and anhydrides) with ≥9 perfluorinated carbons;
   
5. 
   Perfluorooctane sulfonic acid (PFOS), its salts and perfluorooctane sulfonyl fluoride (PFOSF) as listed in Annex B to the Stockholm Convention.
   

22.Data on PFOA are summarized in Table 1 and Table 2.⁵ Tables with data for PFOA salts and PFOA-related compounds are provided in a background document to the risk profile (see section 1.1 of document UNEP/POPS/POPRC.12/INF/5).

Table : Information pertaining to the chemical identity of PFOA

CAS number:	335-67-1
CAS name:	Octanoic acid, 2,2,3,3,4,4,5,5,6,6,7,7,8,8,8-pentadecafluoro-
IUPAC name:	Pentadecafluorooctanoic acid
EC number:	206-397-9
EC name:	Pentadecafluorooctanoic acid
Molecular Formula	C8HF15O2
Molecular Weight	414.07 g/mol
Synonyms	Perfluorooctanoic acid; PFOA; pentadecafluoro-1-octanoic acid; perfluorocaprylic acid; perfluoro-n-octanoic acid; pentadecafluoro- n-octanoic acid; pentadecafluorooctanoic acid; n-perfluorooctanoic acid; 1-cctanoic acid, 2,2,3,3,4,4,5,5,6,6,7,7,8,8, 8-pentadecafluoro

Table : Overview of relevant physiochemical properties of PFOA

Property	Value	Reference/Remark
Physical state at 20°C and 101.3 kPa	Solid	(Kirk, 1995)
Melting/freezing point	54.3°C 44-56.5°C	(Lide, 2003) (Beilstein, 2005) cited in (ECHA, 2013a)
Boiling point	188°C (1013.25 hPa) 189°C (981 hPa)	(Lide, 2003) (Kauck and Diesslin, 1951)
Vapour pressure	4.2 Pa (25°C) for PFO; extrapolated from measured data 2.3 Pa (20°C) for PFO; extrapolated from measured data 128 Pa (59.3°C) for PFO; measured	(Kaiser et al., 2005); (Washburn et al., 2005) (Washburn et al., 2005) (Washburn et al., 2005)
Water solubility	9.5 g/L (25°C) 4.14 g/L (22°C)	(Kauck and Diesslin, 1951) (Prokop et al., 1989)
Dissociation constant	approximately 0.5 <1.6, e.g. 0.5 1.5-2.8	(Johansson et al. 2017) (Vierke et al., 2013) (Kissa, 2001)
pH-value	2.6 (1 g/L at 20°C)	(ECHA, 2015a) (reliability not assignable)

23.Major synthesis routes of fluorotelomer-based substances including side-chain fluorinated polymers as well as an overview of the syntheses routes of major fluoropolymers are illustrated in two figures of supplementary information provided by the Swiss Federal Office for the Environment (FOEN) (see section I of FOEN, 2017). Moreover, specific information regarding the transformation/degradation of fluorotelomers to PFOA is summarized in that document (see section II of FOEN, 2017).

24.There are two manufacturing processes to produce PFOA, its salts and PFOA-related compounds: electrochemical fluorination (ECF) and telomerization. From 1947 until 2002, the ECF process was mainly used to manufacture ammonium perfluorooctanoate (APFO; ammonium salt of PFOA) worldwide (80-90% in 2000) which results in a mixture of branched and linear isomers
(78% linear and 22% branched isomers). In the ECF process, octanoyl fluoride is commonly used to make perfluorooctanoyl fluoride that was further reacted to make PFOA and its salts (Buck et al., 2011).In addition, some manufacturers have used the telomerization process to produce linear PFOA and related compounds. In the telomerizationprocess, an initial perfluoroalkyl iodide (telogen) reacts with tetrafluoroethylene (taxogen) to yield a mixture of perfluoroalkyl iodides with different perfluoroalkyl chain lengths (Telomer A). Telomer Aare reacted further to insert ethylene and create fluorotelomer iodides (Telomer B), which are then used to make a variety of fluorotelomer-based products. Another study suggests that ECF is still used by some manufacturers in China (Jiang et al., 2015). The global production of PFOA using ECF is still ongoing, whereas most of the manufacturers using telomerization have ceased their production of PFOA and related compounds (Wang et al., 2014a).

25.ISO Standard ISO 25101:2009 specifies a method for the determination of the linear isomers of PFOA in unfiltered samples of drinking water, ground water and surface water (fresh water and sea water) using high-performance liquid chromatography-tandem mass spectrometry (HPLC MS/MS). The method is applicable to a concentration range of 10 ng/L to 10 000 ng/L for PFOA. Depending on the matrix, the method may also be applicable to higher concentrations ranging from 100 ng/L to 200 000 ng/L after suitable dilution of the sample or reduction in sample size (ISO 2009). According to a summary of PFOA-methods in ECHA, 2015a, quantification limits vary dependent on the method from 1 ppb to 2000 ppb (further details see ECHA, 2015a,b,c). The unique chemical and physical properties of PFOA prevent it from being measured using conventional analysis. More complex analytical techniques using liquid chromatography and tandem mass spectrometry (LC/MS-MS) have been proven most reliable for analyzing PFOA in biological and environmental samples, and therefore, are the analytical methods of choice (Xu et al., 2013; EFSA, 2008; Loos et al., 2007). This type of analysis has allowed for sensitive determination of many PFASs including PFOA in air, water, and soil (ATSDR, 2015).