In the above section, it has been explained how hazard assessment of an offshore chemical is conducted, based on the test data provided by the chemical supplier on the HOCNF. However, the reproducibility of the tests involved is imperfect.
To provide the most accurate pre-screening of the chemicals submitted for assessment, Cefas therefore takes account of the data it holds for similar substances. This is known as The Global Approach, which is based on the Weight of Evidence principles described by ECHA Practical Guide 2: How to Report Weight of Evidence and in Sections R.4 and R.7a-R.7c of the Guidance on
Information Requirements and Chemical Safety Assessment provided under REACH legislation.
Where multiple biodegradation screening test results of equivalent quality exist, a positive result is accepted over negative results. This application of the global approach may result in the removal of a substitution warning.
Where there are less than 3 values for the same endpoint and they are within 1 order of magnitude the lowest value will take precedence. Where there are greater than 3 values for the same endpoint and they are within 1 order of magnitude the geometric mean will be calculated and used in the assessment
Bioaccumulation (BCF Tests):
A BCF value will take precedence over any other data and will be compared to HMCS criteria. Where more than one BCF value occurs, the highest value will take precedence.
Consideration of global BCF data could remove or apply a substitution warning based partly on Log Pow data, since BCF data always takes precedence over Log Pow data.
Bioaccumulation (Log Pow):
Where only Log Pow data are available and there are less than 3 values the highest value will take precedence. Where there are greater than 3 values the geometric mean will be calculated and used in the assessment. The relevance of WOE approaches conducted under REACH or HMCS will be evaluated on a case by case basis.
It is stressed that the applicability of the Global Approach is only valid where the data being compared relate to the same substance. Expert judgement is used to ensure that this is the case, assisted by database searches and discussions with suppliers, where required.
References: OSPAR Agreement 2012-05, paragraphs 10-12.