UK Chemicals Stakeholder Forum (CSF)
Detailed criteria for identifying chemicals of concern
The detailed technical criteria for identifying chemicals that have intrinsic properties that give cause for concern about their potential to damage the environment or human health via the environment based on persistence, bioaccumulation and toxicity are provided below.
Persistence (P), bioaccumulation (B) and toxicity (T) criteria for identifying substances of concern:
- P = t1/2 water > 2 months or t1/2 soil/sediment > 6 months
- B = log Kow > 4 (Kow >10,000) or Bioconcentration Factor (BCF) >500 where data are available. If experimental BCF is <500, Log Kow does not apply.
- T = Acute L(E)C50 < 1mg/l or long term NOEC < 0.1 mg/l OR category 1 or 2 carcinogen, mutagen or reprotoxin and category 3 mutagens.
OR evidence of endocrine disrupting effects.
Very Persistent (vP) and very bioaccumulative (vB) criteria for identifying substances of concern:
- vP = t1/2 water > 2 months or t1/2 soil/sediment > 6 months
- vB = log Kow >5 (Kow >100,000) or Bioconcentration Factor (BCF) >5000 where data are available. If experimental BCF is <5000, Log Kow does not apply.
In addition to the criteria above, and to assist in prioritising the consideration of chemicals, the Forum has defined the following criteria for substances of highest concern:
- P = t1/2 marine water > 60 days , fresh water > 40 days or t1/2 marine /sediment > 180 days , freshwater sediment > 120days.
- B = log Kow > 4.5 or Bioconcentration Factor (BCF) > 2000 where data are available. If experimental BCF < 2000, Log Kow does not apply.
- T = Acute lethal (effect) concentration L(E)C50 < 0.1 mg/l or long term no observable effect concentration, NOEC < 0.01mg/l OR category 1 or 2 carcinogen, mutagen or reprotoxin, and category 3 mutagens and reprotoxins
OR evidence of endocrine disrupting effects.
Safety net procedures
The Forum also has a safety net procedure for chemicals that do not meet the PBT or vPvB criteria but where there are reasons to believe that the chemicals raise equivalent concerns.
The Forum has been advised by the ACHS that the following types of organic substances or scenarios could be subject to the safety net procedure:
i. Substances that are very toxic (vT) to organisms in the aquatic or terrestrial compartments:
For example, substances with acute toxicity L(E)C50<0.1 mg/L, NOEC<0.01 mg/L (L(E)D50<0.1 mg/Kg, NOED<0.01 mg/Kg). Such substances may not be sufficiently persistent or bioaccumulative to meet the PBT criteria, but due to their potent toxicity may still be a cause for concern, especially if they are continually released to the environment.
ii. Substances which are actually or potentially very bioaccumulative (vB) by whatever mechanism (not necessarily just lipophilic compounds, but also those that accumulate in bone, bind to proteins etc).
These may include, for example, substances with a BCF>10,000 or substances with a log Kow>6, respectively. The committee noted that BCFs must be determined in typical environmental concentrations to give an accurate indication. Bioaccumulation factors should also be used where available. These substances (especially if actually found in biota) may be of concern due to their bioaccumulation, even if their persistence and toxicity do not meet the Stakeholder Forum's criteria. Substances with a very high log Kow, however, may have reduced bioavailability to organisms as they may sorb very strongly to soils and sediments, and may not be freely available in water. Substances which are both bioaccumulative and toxic (i.e. B and T) also may be a cause for concern, especially if the substances are released regularly (i.e. the input load is greater than the degradation removal).
iii. Organic substances that may persist in the environment for many years (t1/2>10 years), or for shorter periods where evidence suggests that adverse effects to the environment and human health may occur.
Evidence of potential adverse effects may be identified by measurement via testing, by modelling predictions, or by monitoring. Adverse effects may include interference with biogeochemical cycles or toxicity to humans or other organisms1. The ACHS will continue to examine this issue and will advise further.
iv. Substances that may cause adverse effects measured, or detected, as novel toxicity endpoints.
Such substances may cause sub-lethal effects that might result in population level effects for exposed species, and could include endocrine-disrupting chemicals, for example. Further scrutiny on a case by case basis may be required to determine whether or not a particular substance should be included in the safety net.
v. The safety net will consider additional substances identified on other appropriate priority lists such as OSPAR, which apply to the UK as a consequence of our European and/or international commitments.
If these substances comply with one or other of the proposed safety net criteria, they will be retained. If not, they will be considered further to determine if they require inclusion in the safety net due to some unforeseen potential hazard or whether they should not form part of the safety net list.
In December 2001 the ACHS advised that the following inorganic substances should be included in the safety net:
vi. Substances that are very toxic to organisms in either the aquatic or terrestrial compartments.
Toxicity thresholds for inorganic substances could be those with acute toxicity of L(E)C50<0.1 mg/L(Kg), or point estimate (or NOEC/D) <0.01 mg/L(Kg).
vii. Substances that are actually or potentially very bioaccumulative in organisms, by whatever mechanism.
These may include, for example, substances with a BCF/BAF>5,000. Note that to eliminate the bioaccumulation concern BCF/BAF data should only be used if the experiments were conducted at environmentally relevant concentrations.
Substances identified under the safety net criteria would require case-by-case consideration by the ACHS prior to the Chemicals Stakeholder Forum's consideration for risk management.
(1) The ACHS considered that dispersive uses of very persistent substances were in themselves a cause for concern, whether or not there was any evidence of harmful effects.
Page last modified: 19 October 2006
Page published 22 December 2000