Particle diameter NM: Points are assigned based on the particles’ deposition
in the respiratory tract, regardless of the
region in the respiratory tract.
1–10nm ......... 10
11–40nm ......... 5
41–100nm ........ 0
Unknown . . . . . . . . 7. 5
Extremely
Unlikely
(0– 25)
Figure 1. Risk level (RL) matrix as a function of severity and probability scores.
Control bands are based on overall risk levels.
Probability Score
Less Likely
(26–50)
Likely
(51–75)
Probable
(76–100)
Very High
(76–100)
RL 3
RL 3
RL 4
RL 4
Solubility NM: Poorly soluble, inhaled
nanoparticles can cause oxidative stress,
leading to inflammation, fibrosis or cancer. Soluble nanomaterials can also
cause adverse effects through dissolution
in the blood, but to a lesser degree.
Insoluble . . . . . . . . . 10
Soluble ........... 5
Unknown . . . . . . . . 7. 5
Severity Score
High
(51–75)
RL 2
RL 2
RL 3
RL 4
Medium
(26–50)
RL 1
RL 1
RL 2
RL 3
Low
(0– 25)
RL 1
RL 1
RL 1
RL 2
Carcinogenicity NM: Points are assigned
based on whether the nanomaterial is
carcinogenic, regardless of whether the
material is a human or animal carcinogen. Little information is available.
Yes .............. 6
No............... 0
Unknown . . . . . . . . 4. 5
Reproductive toxicity NM: Points are assigned based on whether the nanomaterial is a reproductive hazard or not. Little
information on this factor is available.
Yes .............. 6
No............... 0
Unknown . . . . . . . . 4. 5
Control bands by risk level: RL 1: General ventilation; RL 2: Fume hoods or local
exhaust ventilation; RL 3: Containment; RL 4: Seek specialist advice.
No............... 0
Unknown . . . . . . . . 4. 5
Mutagenicity NM: Points are assigned
based on whether the nanomaterial is a
mutagen or not. Little information on
this factor is available.
Yes .............. 6
No............... 0
Unknown . . . . . . . . 4. 5
Toxicity PM: Although research agrees
that nanomaterials can be more toxic
than parent materials, knowledge of the
PM toxicity is a good starting point for
understanding the NM toxicity. Points
are assigned according to the OEL of the
bulk material.
<10µg/m3........ 10
10–100 µg/m3 . . . . . . 5
101 µg/m3–1 mg/m3 2.5
>1mg/m3 ........ 0
Unknown . . . . . . . . 7. 5
Carcinogenicity PM: Points are assigned
based on whether the PM is carcinogenic
or not.
Yes .............. 4
No............... 0
Unknown ......... 3
Dermal hazard potential of PM: Points
are assigned on whether the PM is a
dermal hazard or not.
Yes .............. 4
No............... 0
Unknown ......... 3
Dermal toxicity NM: Points are assigned
based on whether the nanomaterial is a
dermal hazard or not. Little information
on this factor is available.
Yes .............. 6
No............... 0
Unknown . . . . . . . . 4. 5
Reproductive toxicity of PM: Points are
assigned on whether the PM is a reproductive hazard or not.
Yes .............. 4
No............... 0
Unknown ......... 3
Asthmagen PM: Points are assigned
based on whether the PM is an asthmagen or not.
Yes .............. 4
No............... 0
Unknown ......... 3
The overall severity score is determined based on the sum of all the points
from the severity factors. The maximum
score is 100. An overall severity score of
0– 25 is considered low severity; an overall severity score of 26–50 is considered
medium severity; an overall severity
score of 51–75 is considered high severity;
and an overall severity score of 76–100
is considered very high severity.
Asthmagen NM: Points are assigned
based on whether the nanomaterial is an
asthmagen or not. Little information on
this factor is available.
Yes .............. 6
Mutagenicity of PM: Points are assigned
on whether the PM is a mutagen or not.
Yes .............. 4
No............... 0
Unknown ......... 3
Probability Factors
The probability scores are based on factors determining the extent to which
employees may be potentially exposed
to nanomaterials:
Estimated amount of NM used during
operation: For nanomaterials embedded
on substrates or suspended in liquid, the
amount is based on the mass of the
nanomaterial and not the substrate or
liquid portion.
