Risk Assessment

Antimony substances, and in particular Diantimony Trioxide, have been risk assessed a number of times previously:

  • Since 1987: The US Environmental Protection Agency (US EPA) concluded that an oral reference dose of 0.0004 mg/kg/day is deemed to be without appreciable risk of deleterious effects during a lifetime.  The report is available here.
  • Since 1995: The US EPA concluded that an inhalation reference concentration of 0.0002 mg/m³ is deemed to be without an appreciable risk of deleterious effects during a lifetime.  The report is available here.
  • The above values are regularly revised and recorded in the US EPA Risk Assessment Information System (RAIS) Toxicity Values and Physical Parameters are available here.
  • Since 2003: The World Health Organization (WHO) concluded on a Tolerated Daily Intake (TDI) of 6 µg/kg bw and a guideline value of 20 µg/l is allowable in drinking water.  The report is available here
  • Since 2004: The use of Diantimony Trioxide as catalyst for the polymerization of PET resin was deemed safe by the European Food Safety Administration (EFSA), with a established migration limit of 0.04 mg/kg of food (as Antimony) (allowing for 10% of the Tolerated Daily Intake (TDI) being allocated to food contact materials.  The report is available here.
  • In 2008: The OECD concluded in the Screening Information Dataset (SIDS) initial assessment profile for Diantimony Trioxide that it was a substance meriting workplace exposure monitoring (in addition to the on-going animal testing at US NTP level), and of low priority for any further environmental work.  The profile is available here.
  • Since 2008: EU authorities concluded under the Existing Substances Regulation 793/93, that there was then no need for further information and/or testin,g and no need for risk reduction measures beyond those which were already in place (i.e. a suspected carcinogenicity classification; maximum air emission limit values for waste incinerators; limits for drinking water, food contact materials, cosmetics, and toys; and occupational exposure limit values).  The report is available here.
  • Since 2010…: Cf. EU REACH Registration and EU REACH Evaluation (see below)

EU REACH Registration

i2a has lead the registration of 10 Antimony substances under the REACH (Registration, Evaluation, and Authorisation of Chemicals) Regulation (1907/2006/EC), the EU‘s framework legislation on chemicals.

The 10 Registration Dossiers contain all use, phys-chem, hazard, classification, exposure and risk information required by the regulation. Dossiers have made use of read-across evidence wherever possible to prevent unnecessary vertebrate animal testing while performing conservative hazard, exposure and risk assessments of each Antimony substance and their various uses. The Dossiers are regularly updated to reflect new evidence and comply with the latest requirements.

EU REACH Evaluation

What? Several Antimony substances (including Antimony metal, Diantimony Trioxide, Diantimony Trisulphide, Antimony trichloride and Antimony tris(ethylene glycolate)) have been included in the EU’s “Community Rolling Action Plan” (CoRAP) for Evaluation under REACH (1907/2006/EC), the EU‘s framework legislation on chemicals.

Evaluation is the process whereby selected substances are subject to additional regulatory scrutiny by ECHA or one of the Member States. Germany is the EU Member State responsible for the EU Substance Evaluation of Antimony substances.  For every substance undergoing Substance Evaluation, ECHA performs a Compliance Check, to ensure that the basic REACH information requirements have been fulfilled.

Why? The main reason for the Evaluation of Antimony trivalent substances is the assessment of new toxicological evidence regarding their potential carcinogenicity, namely the US NTP Carcinogenicity studies with Diantimony Trioxide in rats and mice, published in December 2017.  

When and how? The Evaluation process will involve: i) a number of exchanges between i2a (representing the registrants of the evaluated Antimony substances) and ECHA, ii) generating requested information, and iii) updating the concerned REACH Registration Dossiers so that these reflect the most recent toxicological evidence and exposure information. 

The following Evaluation schedule has been estimated by i2a (a more detailed process overview is available here):

  • 2018: Start of the Evaluation, and Dossier updates
  • 2019: Draft Evaluation Decisions, registrants’ responses, and Dossier updates
  • 2020: Final Evaluation Decisions, registrants’ responses, and Dossier updates
  • 2021-2023: Information generation, and Dossier updates
  • 2023: Evaluation of new evidence and follow-up (either more information can be requested, or a number of (regulatory) measures can be proposed)

i2a will be coordinating the generation and collection of information necessary for decision-making.  Information requests will be made to i2a Members and members of the relevant Downstream User associations, who use Antimony substances.  Some of the information requests will be subject to strict deadlines and/or require the engagement and commitment of various representatives of the Antimony value chain.  

Follow-up regulatory action may include a proposal for an EU harmonized classification, and/or EU workplace (e.g. occupational exposure limit value or OEL) and/or product restrictions.  Each recommended follow-up action would need to be formulated as a specified regulatory proposal and undergo the steps/time foreseen under each specific legislative process, as from 2023.

The REACH Evaluation process permits proceeding with a stepwise gap-filling process to achieve efficient Antimony substance regulation. In the interim the existing precautionary measure advocated by i2a and its Members remains valid: as long as the generation and inhalation of dust is avoided, there is no increased risk for workers or users of Antimony and its compounds. This precaution should be implemented throughout the value chain.

Who?  The information requested during the Evaluation process requires a tailored research program including comparison/ranking, in vitro, and in vivo studies.  It also requires the generation, collection and assessment of workplace exposure data.  A successful Evaluation process therefore requires the entire Antimony value chain’s input and support.  Stakeholders can help by:

  • Participate in the events organized by i2a (e.g. technical workshops, annual Antimony Days, etc.); and
  • become a Member of i2a, as Full or Associate Member; and/or
  • become a Member of the relevant Antimony Downstream User association(s); and
  • contribute to the information requests by the given deadlines.

Download ECHA’s guide on how to act in Substance Evaluation.

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