Compliance and safety for the supply of chemical products
REACH
Chemical Safety Assessment
Services
Alchemy Compliance can perform physico-chemical, health and environmental risk assessments. Risk assessment is the basis of the Chemical Safety Report in REACH.
Risk assessment requires an understanding of the hazardous properties of substances. Alchemy can advise on testing strategies, and place tests at a laboratory best suited to your needs. We can also advise on alternative sources of data, eg from literature and structure–activity relationships.
From the hazard information, we can derive critical parameters for the assessment, such as derived-no-effect-levels (DNELs) for human health and predicted no-effect concentrations (PNECs) for the environment.
We can assess occupational, consumer and environmental exposures using data from current guidance documents, and computer modelling (eg EASE, EUSES). These assessments are the basis of REACH Exposure Scenarios, a necessary part of extended safety data sheets (ext-SDSs).
The exposure, combined with the information on the hazards of a particular chemical, allows the assessor to characterise the risk, and determine whether a particular use is safe. REACH obliges registrants marketing a substance at ≥10 t/year to conduct a chemical safety assessment (ie risk assessment), and provide it to the European Chemicals Agency (ECHA) as part of the registration dossier.
Further information
For a fuller explanation, see: Chemical Risk Assessment for REACH; Chapter 10, in Essential Guide to REACH; Wolters Kluwer (UK) Ltd.; September 2009, authored by Dr Mel Cooke, Alchemy Compliance Ltd.
For a schematic overview, see our Chemical Safety Asessment Under REACH graphic.
Chemical risk assessment – Human Health
Risk assessment is the pillar of chemical regulation that is concerned with the protection of man and the environment. The assessor evaluates a substance by comparing its hazardous properties with the exposures of specified populations (industrial, professional, and consumer, and people exposed via the environment), to estimate the likelihood that adverse effects will occur.
Therefore, the assessor can conclude that an extremely hazardous substance can be used safely (ie has an acceptable risk), provided that there are no significant exposure to it during its lifecycle. Thus, the relationship between risk, hazard and exposure can be depicted as in Equation 1 below, and is the reason that the chemical industry is generally opposed to restricting a chemical product based solely on its hazardous properties.
Risk = Hazard × Exposure (Equation 1)
REACH obliges registrants of a substance marketed at ≥10 t/year to conduct a chemical safety assessment as part of the registration dossier (Article 14 of REACH).
Chemical safety (or risk) assessment covers the life cycle of a substance from manufacture through use to disposal, accounting for its properties, stability and effects at each stage. The risk assessment is used in regulatory schemes to decide if further information or risk reduction measures are required at any part of the lifecycle.
We assess the risk to human health by comparing the calculated or measured exposure data for a specific human population with toxicological data extrapolated from animals, as in Equation 1.
The most important toxicological parameter for systemic effects (those that occur in parts of the body distant from the site of contact), is the no-observed-adverse-effect level (NOAEL), usually derived from repeated-dose animal studies (28 d, 90 d, or 2 y exposures in the rat). From such parameters, the assessor can calculate the derived-no-effect levels (DNELs), which establish a safe exposure level for a particular exposure scenario.
For local effects (ie those that occur at the site of contact with the chemical, such as irritation), DNELs are harder to derive, and the risk is pragmatically controlled using risk management measures, such as personal protective equipment, or ventilation.
The risk assessment is more complicated for effects where there is no identified threshold concentration (ie there is no cut-off dose below which the effect is not seen), particularly for carcinogenic and mutagenic substances. In these cases, a stringent level of acceptable risk is established, called the Derived Minimal Effect Level (DMEL).
The conditions of exposure are defined in REACH by the use of exposure scenarios (ESs), which comprise a set of operational conditions (OCs; eg process temperature, concentration of substance) and risk management measures (RMMs; eg local exhaust ventilation, protective equipment). For each ES, the assessor makes an estimate of the exposure, using measured or calculated data.
If the exposure estimate is equal to or higher than the DNEL or DMEL, the substance will be of concern with regard to the population considered. The assessor may decide that additional information, either concerning exposure or toxicity, is necessary to refine the chemical risk assessment. Usually, refinement of the exposure assessment is recommended before further in vivo studies are conducted, owing to animal welfare considerations. If the exposure cannot be controlled within the DNEL or DMEL, then the use pattern given in the exposure scenario is designated as a ‘use advised against’ which is recorded in the safety data sheet.
Where the exposure estimate is less than the DNEL or DMEL, the use pattern in the ES can be considered safe, and this ES is given as an annex in the extended safety data sheet (ext-SDS).
Environmental Risk Assessment
The assessor uses a different procedure for environmental risk characterisation. The aim is to protect ecosystems (not individual animals), using test data on representative species. In REACH, the basic ecotoxicity test-battery comprises acute effects in fish, Daphnia, and algae. In this case, we calculate a predicted no-effect concentration (PNEC) by dividing the LC50 concentration (concentration of substance that causes death in 50%) or no-observed-effect concentration (NOEC) in the most sensitive species by an assessment factor, which decreases with the amount of information available, for example if long-term data are also available.
The assessor should also identify whether the substance is likely to be persistent, bioaccumulative and toxic (PBT), or very persistent and very bioaccumulative (vPvB), according to the criteria given in Annex XIII of REACH.
We obtain the predicted environmental concentration (PEC) either by measurement, or by calculation using release data and fate and behaviour modelling. Finally we divide the PEC by the PNEC and if this ratio is less than one, there is considered to be no immediate concern. If greater than one, the assessor may ask for more detailed information on the substance, its release into the environment, its distribution, or its ecotoxicology, in order to refine the risk assessment. If the ratio remains unfavourable after refinement, risk reduction measures, including restriction on marketing or use, may be imposed.
The calculations concerning the fate and distribution of a chemical into the various environmental compartments (water, air, soil, sediment, etc.) once it enters the environment are often complicated, and the use of computation methods is frequently required. The foremost regulatory programme for environmental risk assessment in the EU is EUSES, available from the European Commission.
Recommendations for risk reduction might include:
Modifications to classification, packaging, labelling, the safety data sheet, or the recommended precautions or emergency measures
Measures for the protection of man and the environment, such as limits for worker exposure or environmental discharge
Restrictions on marketing under the provisions of REACH, including uses advised against, or more blanket restrictions given in REACH Annex XVII
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