Hazard Assessment

CHARM

The OCNS conducts hazard assessments on chemical products that are used offshore.  The CHARM model calculates the ratio of Predicted Effect Concentration against No Effect Concentration (PEC: NEC), and is expressed as a Hazard Quotient (HQ), which is then used to rank the product. The HQ is converted to a colour banding (see table 1 below), which is then published in:

Please Note: the definitive ranked list does not indicate which countries the products are registered for nor does it indicate the products that have substitution warnings. In addition the Netherlands does not use the colour banding system

Data used in the CHARM assessment include toxicity, biodegradation and bioaccumulation.

The CHARM model is divided into 4 main algorithms

• Production
• Completion / Workover
• Drilling
• Cementing

Table 1.  The OCNS HQ and colour bands

Minimum HQ value	Maximum HQ value	Colour banding
>0	<1	Gold	Lowest Hazard Highest Hazard
≥1	<30	Silver
≥30	<100	White
≥100	<300	Blue
≥300	<1000	Orange
≥1000		Purple

Non-CHARM

Products not applicable to CHARM model (i.e. inorganic substances, hydraulic fluids or chemicals used only in pipelines) are assigned an OCNS grouping A – E, with A being the greatest potential environmental hazard and E being the least (see below table)

This system awards the offshore chemical a letter grouping between A and E. (N.B. care should be taken not to confuse these values with the results of the Netherlands pre-screening scheme). Each individual substance in an offshore chemical should be ranked by applying the OCNS Ranking Scheme. The overall ranking is determined by that substance having the worst case OCNS ranking scheme assignment. The method of assignment of the OCNS letter grouping is described below.

Initial Grouping

The initial group is determined using the table 1. All submitted toxicity data for the product are compared with the table and the value giving the worst case ‘Initial Grouping’ (i.e. the test giving the most toxic response) is used as the initial Group for the substance. 

Table 1: Initial OCNS grouping

• Aquatic toxicity refers to the Skeletonema costatum EC50, Acartia tonsa LC50, and Scophthalmus maximus (juvenile turbot) LC50 toxicity tests.
• Sediment toxicity refers to the Corophium volutator LC50 test.

Adjustment for environmental performance to determine final Group

The final grouping is determined using table 2 as a guide.  Select the column that applies to the candidate product and adjust the initial Group accordingly.  If the classification should theoretically move beyond Group A or E, the product will nevertheless be assigned to that particular Group.

Table 2: Adjustment criteria for OCNS grouping

Definitions of terms used in the classification table: 

• Readily biodegradable - Results of >60% biodegradation in 28 days to an OSPAR HOCNF accepted ready biodegradation protocol.
• Inherently biodegradable - Results of >20% and <60% to an OSPAR HOCNF accepted ready biodegradation protocol or result of  >20% by OSPAR accepted Inherent biodegradation study.
• Not biodegradable - Results from OSPAR HOCNF accepted ready biodegradation protocol or inherent biodegradation protocol are <20%.
• Non-bioaccumulative/non-bioaccumulating - Log Pow <3, or results from a bioaccumulation test (preferably using Mytilus edulis) demonstrates a satisfactory rate of uptake and depuration, or the molecular mass is > 700.
• Bioaccumulative/Bioaccumulates - Log Pow >3, or results from a bioaccumulation test (preferably using Mytilus edulis) demonstrates an unsatisfactory rate of uptake and depuration, and the molecular mass is < 700.
• Aquatic toxicity test result - LC/EC50 data for Skeletonema costatum, Acartia tonsa or Scophthalmus maximus (Juvenile turbot) (units = ppm or mg/litre)
• Sediment toxicity test result - LC50 data for Corophium volutator (units = ppm or mg/Kg).