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Appendix 3: Background information on hazardous air contaminants

 

Contaminant Health effects Classification Unit risk x 10-6 Various guidelines (µg/m3)
(annual averages unless otherwise stated)
IARC* US EPA* (potency) WHO US EPA CARB UK EC TWA/ 100 WHO US

Benzene

Haemotoxic; genotoxic; carcinogenic

1

A (medium)

4.4-7.5

8.3

29

18 (now)
3.6 (goal)

10 (now)
5 (2010)

18

-

-

1,3-Butadiene

Neurological; irritation of eyes, throat, lungs and nose; mutagenic; carcinogenic (?)

2A

B2 (medium)

-

280

170

2.4

-

24

-

-

Formaldehyde

Irritation of eyes, throat, nose and respiratory symptoms; nasal cancer

2A

B1 (medium)

Very low

13

6

-

-

9.2

100 normal

10 hypersensitive (30-min)

-

Acetaldehyde

Irritation of eyes, throat, nose and respiratory system; nasal cancer

2B

B2 (low)

15-90

2.2

2.7

-

-

3600

2400 (24-hour)

9 (RfC)

Benzo(a)pyrene

Dermatitis; photosensitisation; eye irritation; cataracts; lung cancer (?)

1

B2 (medium)

87,000

-

-

-

-

-

-

-

Mercury**

CNS; gastrointestinal; respiratory system; kidney

2B(m)
3(I)

C (medium)
D (low)

-

-

-

-

-

0.1(al)
0 25(I)
1.0(ar)

1(I)

0.3(I)
(RfC)
0.3(I)
(REL)

Chromium VI

Respiratory; gastrointestinal; liver; kidney; immune system; blood

1

A (high)

11,000-130,000

1200

150,000

-

-

0.1-0.5

-

0.0023

Chromium III and metal

3

D

-

-

-

-

-

5.0

-

-

Arsenic (inorganic)

Gastrointestinal; haemolysis; central and peripheral NS; eyes; skin; mucous membrane

1

A (high)

1500

4300

1500

-

-

0.1

-

0.41 (REL)

Arsine

1.7

-

0.055 (RfC)

* IARC classes and US EPA equivalents are as follows.

IARC Descriptor USEPA

1

The agent (mixture) is carcinogenic to humans. The exposure circumstances entail exposures that are carcinogenic to humans.

A

2A

The agent (mixture) is probably carcinogenic to humans. The exposure circumstances entail exposures that are probably carcinogenic to humans.

B1

2B

The agent (mixture) is possibly carcinogenic to humans. The exposure circumstances entail exposures that are possibly carcinogenic to humans.

B2, C

3

The agent (mixture or exposure circumstances) is not classifiable for humans.

D

4

The agent (or mixture) is probably not carcinogenic to humans.

 

** Abbreviations for mercury: Organic (o) = [methyl (m), aryl (ar), alkyl(al)]; Inorganic (I) = elemental and other inorganic compounds.

For more information about these contaminants, please read Air Quality Technical Report 13.