Hazard assessment
Chemical Hazard and Risk Management (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).
This is expressed as a Hazard Quotient (HQ), which is then
used to rank the product.
The HQ is converted to a colour banding, illustrated in Table 1,
which is then published on the Definitive Ranked Lists of Registered Products, Excel format (ZIP, 369.58 KB, updated 31 January 2012)
.
Data used in the CHARM assessment include toxicity,
biodegradation and bioaccumulation.
The CHARM model is divided into four main algorithms:
- production
- completion/work-over
- drilling
- cementing.
Table 1: 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 the CHARM model (i.e. inorganic
substances, hydraulic fluids or chemicals used only in pipelines)
are assigned an OCNS grouping, A - E. Group A includes products
considered to have the greatest potential environmental hazard and
Group E the least (see Tables 2 and 3 below).
Each individual substance in an offshore chemical is 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.
The way in which each OCNS group letter is assigned can be seen
in more detail here:
Initial grouping
The initial group is determined using Table 2. All
submitted toxicity data for the product are compared against the
table. 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 2: Initial OCNS grouping
| Initial grouping |
A
|
B
|
C
|
D
|
E
|
|
Result for aquatic-toxicity data (ppm)
|
<1
|
>1-10
|
>10-100
|
>100-1,000
|
>1,000
|
|
Result for sediment-toxicity data (ppm)
|
<10
|
>10-100
|
>100-1,000
|
>1,000-10,000
|
>10,000
|
- 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 3 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 3: Adjustment criteria for OCNS
grouping
| Increase by 2 groups (e.g. from C to E) |
Increase by 1 group (e.g. from C to D) |
Do not adjust initial grouping |
Decrease by 1 group (e.g. from C to B) |
Decrease by 2 groups (e.g. from C to A) |
| Substance is readily biodegradable and is
non-bioaccumulative |
Substance is inherently biodegradable and is
non-bioaccumulative |
Substance is not biodegradable and is
non-bioaccumulative
or |
Substance is inherently biodegradable and
bioaccumulates |
Substance does not biodegrade and
bioaccumulates |
| |
|
Substance is readily biodegradable and
bioaccumulates |
|
|
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%, or half-life values derived from aquatic
simulation tests indicate persistence
- Non-bioaccumulative:
Log Pow <3, or BCF ≤100 and the molecular
weight is ≥700
- Bioaccumulative: Log Pow ≥3, or BCF
>100 and the molecular weight is <700, or if the conclusion
of a weight-of-evidence expert judgement under OSPAR Agreement
2008-5 is negative
- Aquatic toxicity test result:
LC50/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).