Substitution Notices

A chemical has a substitution warning, what does this mean and what action must be taken?

Substitution is an important component of the Harmonised Mandatory Control Scheme (HMCS), and the UK is obliged to implement a strategy to replace chemicals that have been identified as candidates for substitution, or contain components that have been identified as candidates for substitution

During the risk-assessment process, operators are required to consider the selection of products both in terms of the magnitude of their Risk Quotient (RQ) and the presence of hazardous substances, including candidates for substitution. Operators are required to provide a robust defence for the continued use of products that have a high RQ or contain candidates for submission.

Chemical suppliers must consider the advice they provide to operators that justifies continued use of any product containing candidates for substitution. In addition, suppliers should consider an approach for the replacement of any undesirable components, leading to the reformulation and re-certification of products.

Operators are encouraged to select products without a substitution warning. Therefore, a supplier may wish to seek alternatives at the product-development stage. However, there may be good technical reasons why a particular substance cannot immediately be substituted. The supplier should highlight these to operators so that they can include this information in their justification for continued use of the product.

Why does the surfactant in my product have a Substitution warning?

The Log Pow cannot be calculated and used for surfactants since they are unable to partition between two phases, due to their chemical surface binding properties, accumulation at interfaces and emulsion formation. A precautionary approach is taken where data are ambiguous or missing, therefore substitution warnings will be applied to those surfactants that have a molecular weight of <700 and are either:

  • less than 60% or 70% biodegradable in 28 days (according to the test protocols), or
  • toxicity test results have an EC50/LC50 <10 mg/l

unless Cefas is satisfied that other evidence submitted by the supplier indicates that the substance should not bioaccumulate.

Can the Bioaccumulation factor (BCF) test be conducted for surfactants?

Conducting BCF tests with surfactants is technically challenging but possible by applying the guidance in the following OECD documents:

How does Cefas treat the test data for surface-active substances?

Where no relevant scientifically robust data on a surfactant from standard OECD tests suggesting that a substance does not bioaccumulate exists, Cefas will apply the precautionary principle assuming the substance will bioaccumulate. However, if there is evidence (for example from biodegradation studies, toxicokinetic studies, including metabolism, residue or monitoring studies) that indicates a substance is unlikely to bioaccumulate, Cefas will evaluate this data and apply expert judgement.

My product is likely to attract a substitution warning because of a poor result in an OECD 306 biodegradation test. What can be done to check it?

Paragraph 44 of the OECD protocol says: "Owing to the relatively high-test concentrations as compared with most natural systems, and consequently an unfavourable ratio between the concentrations of test substance and other carbon sources, the method is to be regarded as a preliminary test which can be used to indicate whether or not a substance is easily biodegradable. Accordingly, a low result does not necessarily mean that the test substance is not biodegradable in marine environments but indicates that more work will be necessary for this to be established."

Chemical suppliers are therefore encouraged to submit additional data to prove that a substance is or is not biodegradable. For substances shown to be <60% or <70% biodegradable (depending on the test endpoint) in an OECD 306, this could be an extended OECD 306 or an OECD 301 ready test. If the OECD 306 test showed the substance to be <20% biodegradable, or if a ready aerobic biodegradation test has not been performed, it will be assumed that the substance is persistent in aerobic conditions unless a simulation test (e.g. OECD 308, OECD 309) is performed, which indicates the opposite

Why are substitution warnings assigned to the whole product, when the component to which the warning applies is only a small fraction of the total composition?

The UK is obliged to regularly report to OSPAR the total quantities of chemicals that are used and discharged offshore. Under OSPAR Recommendation 2006/3, Contracting Parties should have phased out by 1 January 2017 the discharge of offshore chemicals that are, or which contain substances, identified as candidates for substitution, except for those chemicals where, despite considerable efforts, it can be demonstrated that this is not feasible due to technical or safety reasons.

It therefore follows that when selecting products for use offshore, operators should approach their suppliers for more detailed information on products containing candidates for substitution. This allows consideration of the risks that might be posed by the use and especially the discharge of such materials. Regulatory authorities are obliged to flag the use of endocrine-disrupting substances, even if present at low levels.