COMMENTS ON AN ANNEX XV DOSSIER FOR IDENTIFCATION OF A SUBSTANCE AS SVHC AND RESPONSES TO THESE COMMENTS

Substance name: Dibutylbis(pentane-2,4-dionato-O,O')tin
CAS number: 22673-19-4
EC number: 245-152-0

The substance is proposed to be identified as meeting the following SVHC criteria set out in Article 57 of the REACH Regulation: Toxic for reproduction (Article 57c)

Disclaimer: Comments provided during the consultation are made available as submitted by the commenting parties. It was in the commenting parties own responsibility to ensure that their comments do not contain confidential information. The Response to Comments table has been prepared by the competent authority of the Member State preparing the proposal for identification of a substance of very high concern. RCOM has not been agreed by the Member State Committee nor has the document been modified as result of the MSC discussions. The table does not contain any confidential information.

PART I: Comments and responses to comments on the SVHC proposal and its justification

General comments on the SVHC proposal
Number / Date	Submitted by (name, submitter type, country)	Comment	Responses	
5364
2020/04/08	IPI Global Ltd,
Company,
United Kingdom	Attachment: 5364_DIBUTYLBIS(PENTANE-2,4-DIONATO-O,O')TIN.pdf
	Thank you for your comment. 

Information on technical alternatives may, where relevant, be considered at later stages of the risk management process.	
5366
2020/04/09	TIB Chemicals AG,
Company,
Germany	Attachment: 5366_LOD R2SnCl2.pdf

Confidential attachment removed	Thank you for your comments.

The substance meets the criteria and goal of the SVHC roadmap 2020 based on its harmonised classification as Repr. 1B according to the CLP regulation (1272/2008). 
As this is applicable law at present, the current classification will not be questioned nor discussed. As a reprotoxic substance cat. 1B dibutylbis(pentane-2,4-dionato-O,O')tin meets the criteria of REACH Art. 57c.
Any reason to question the harmonised classification of the substance must go through the CLP regulation process.	
5370
2020/04/15	Health and Environment Alliance (HEAL),
International NGO,
Belgium	The Health and Environment Alliance (HEAL) thanks Sweden for its proposal to identify Dibutylbis(pentane-2,4-dionato-O,O')tin (hereafter DBTP)  as SVHC under article 57(c) and we fully support this proposal.

DBTP has already been classified as toxic for reproduction (category 1B) by ECHA risk assessment committee (December 2017), we consider the SVHC identification to be unequivocal.	Thank you for your support.	

Specific comments on the justification
Number / Date	Submitted by (name, submitter type, country)	Comment	Responses	
5364
2020/04/08	IPI Global Ltd,
Company,
United Kingdom	See the corresponding embedded attachment in table 1 of Part I: 5364_DIBUTYLBIS(PENTANE-2,4-DIONATO-O,O')TIN.pdf	Thank you for your comment.

Please find answers to your comment in table 1 to Part 1.	
5366
2020/04/09	TIB Chemicals AG,
Company,
Germany	See the corresponding embedded attachment in table 1 of Part I: 5366_LOD R2SnCl2.pdf
See the corresponding embedded attachment in table 1 of Part I: Confidential attachment removed	Thank you for your comments.

Please find answers to your comments in table 1 to Part 1.	
5370
2020/04/15	Health and Environment Alliance (HEAL),
International NGO,
Belgium	The Health and Environment Alliance (HEAL) thanks Sweden for its proposal to identify Dibutylbis(pentane-2,4-dionato-O,O')tin (hereafter DBTP)  as SVHC under article 57(c) and we fully support this proposal.	Thank you for your support.	
5374
2020/04/16	CHEM Trust Europe,
International NGO,
Germany	CHEM Trust supports the inclusion of Dibutylbis(pentane-2,4-dionato-O,O')tin in the REACH candidate list owing to its classification as reproductive toxicant 1B which fulfills the criterion of article 57 c).	Thank you for your support.	
5391
2020/04/17	Norway,
Member State	The Norwegian CA supports that dibutylbis(pentane-2,4-dionato-O,O')tin should be identified as a substance of very high concern and should be included in the Candidate List.

Norway also has a concern for other structurally similar organic tin compounds and is assessing them for action under CLP/REACH.	Thank you for your support.	
5402
2020/04/17	ChemSec,
International NGO,
Sweden	ChemSec agrees on the SVHC identification of this substance based on its classification as toxic for reproduction.	Thank you for your support.	

PART II: Comments and responses to comments on uses, exposures, alternatives and risks

Specific comments on use, exposure, alternatives and risks
Number / Date	Submitted by (name, submitter type, country)	Comment	Responses	
5364
2020/04/08	IPI Global Ltd,
Company,
United Kingdom	pag.6 We are proposing a Technical alternative to the handling recommendations provided in this document for reducing exposure to Dibutylbis(pentane-2,4-dionato-O,O')tin significantly below OELs in accordance with the EU[4],[5],[6] directives on carcinogens and mutagens – the IPI closed system has been proved effective for handling CMR liquids in Europe.
These Directives clearly acknowledge the usefulness of a closed system for the protection of workers. In fact, it is specifically mentioned that “where possible, a carcinogenic (mutagenic and reprotoxic) substance should be substituted with a less-hazardous alternative – otherwise carcinogens (mutagenic and reprotoxic) must, so far as is technically possible, be manufactured and used in a closed system to prevent exposure of workers”.
Together with the OQEMA-HSE study on Hydrazine Hydrate (Carc.1B) with level below 0.02 ppm, Archroma exposure result for Formaldehyde (carc.1B) with level around 0.03 ppm and SAFECHEM exposure to Tetrachloroethylene 25 times below the established level recommended, it confirms that using our closed loop system can help to reduce drastically the exposure of the operator and the environment even further below the threshold recommended by scientists and EU and World Regulatory Agencies.
Moreover, closed loop technology can also help compliance with the EU Circular economy[8] stipulations and amended EUROPEAN PARLIAMENT AND COUNCIL DIRECTIVE 94/62/EC of 20 December 1994 on packaging and packaging waste[9] with the latest Commission Implementing Decision (EU) 2019/665 of 17 April 2019[10]  and the UN SDG[11] to protect the environment reducing the amount of plastic, metals, water, raw material, energy, etc. and gives a significant economic return for companies.	Thank you for your comment.

Please find answers to your comment in table 1 to Part 1.	
		See the corresponding embedded attachment in table 1 of Part I: 5364_DIBUTYLBIS(PENTANE-2,4-DIONATO-O,O')TIN.pdf		
5366
2020/04/09	TIB Chemicals AG,
Company,
Germany	Swedish Chemicals Agency (KEMI) added to their „proposal for identification of a substance for very high concern on the basis of  the criteria set out in REACH Article 57“ the table „Example of structurally similar substances used in read-across“. In our opinion there is no solid scientific basis for this read across. The table shows dibutyltin dichloride (DBTC) as the putative common product of gastric hydrolysis of all Dibutyltin compounds.  Due to analytical limitations this postulate has been the usual approach in the past and found even entry into scientific literature.  A number of recent studies using 119Sn-NMR to analyze the gastric metabolites of organotin compounds show that the gastric hydrolysis of organotin compounds is highly differentiated. The Dibutyltin compounds listed in the table have no biological active single gastric metabolite, which would suggest a unique common toxophore for all Dibutyltin compounds. The postulated analogy substance DBTC is not formed and is therefore not present.

In 2019 the Austrian Umweltbundesamt published the study „ Conversion of organotin compounds in the gastric environment - NMR based investigation of the hydrolysis of DOTE and DBTM“. The study demonstrates clearly, that the gastric hydrolysis product of Dibutyltin carboxylate and Dibutyltin oxide is a Dimeric Distannoxanne, which cannot pass biological membranes due to it’s high molecular weight. An equilibrium between a monomeric distannoxane and a dimeric distannoxane which has been discussed in other place does not occur. Such equilibria, despite on the interpretation of KEMI are not described in literature. Such equilibria would easily been seen in the 119Sn-NMR spectra.   Furthermore no Dibutyltin dichloride was detected. The authors of the study accessed a detection limit of 3 % for the Dibutyltin oxide.

Based on the findings of UBA, and with the same measurement method, in a further study by University Heidelberg and TIB Chemicals AG,  a much lower detection limit for Dibutyltin dichloride could be shown, as Sn is below 0.01 % (see non confidential attachment LOQ_R2SnCl2.pdf).
The in-vitro results were confirmed by an OECD 414 study with Dibutyltin oxide in rats (see confidential attachment OECD414_DBTO).

With regard to the foetal data, there was no adverse effect of DBTO administration at any dose level. Foetal body weights and sex ratio were unaffected and considering the external, visceral and skeletal examinations, all incidences of individual abnormalities are considered to have sporadic distribution of low incidence, reflecting normal variations in data. For the overall incidences of litter or foetal malformations and variations, the high dose actually has less abnormalities when compared with controls.

On the basis of the above findings, we concur with the report conclusion that the maternal No-Adverse-Effect-Level (NOAEL) is 3 mg/kg/day due to adverse pregnancy outcomes from embryo-lethality and excessive maternal toxicity at 6 mg/kg/day. Changes in thymus weight at all dose levels and sporadic clinical findings of reddened oral material at lower dose levels are considered non-adverse. DBTO is considered not teratogenic in rats at dose levels up to 6 mg/kg/day
Based on the above, we strongly disagree to the approach to treat a group of Dibutyltin compounds as a single substance: The gastric hydrolysis products of different dibutyltin compounds are highly differentiated, in the present case the substance DBTC, on whose properties the reasoning is based, is not even formed, and the identified metabolite, a dimeric distannoxane is not biologically active.	Thank you for your comments.

The substance meets the criteria and goal of the SVHC roadmap 2020 based on its harmonised classification as Repr. 1B according to the CLP regulation (1272/2008), and not on its relation to other dibutyltin substances.

	
		See the corresponding embedded attachment in table 1 of Part I: 5366_LOD R2SnCl2.pdf
See the corresponding embedded attachment in table 1 of Part I: Confidential attachment removed		
5370
2020/04/15	Health and Environment Alliance (HEAL),
International NGO,
Belgium	Important considerations to add to our general comment of support of this SVHC identification:
- Although only one developmental toxicity study of DBTP is available, it is assumed that all dibutyltin compounds degrade into dibutyltin; and dibutyltin compounds are "repeatably and reliably associated with a syndrome of malformations in the oroglossal region” (as per registration dossier at https://echa.europa.eu/registration-dossier/-/registered-dossier/11900/7/9/1).
- We note that uses of DBTP are widely dispersed with high potential for human exposures, which further justifies a prioritization of this SVHC identification.	Thank you for your support.	
5374
2020/04/16	CHEM Trust Europe,
International NGO,
Germany	CHEM Trust considers that high priority should be given to consider further regulatory measures in particular for consumer and wide dispersive uses, using a group approach to other dibutyltins with similar problematic properties.	Thank you for your support.