Table 5.

Air exposure levels corresponding to toxicological endpoints for the general public.

Agency/guideline	Critical effect	Endpoint	Uncertainty factor	Guideline value	Reference
Non-cancer
USEPA RfC	Decreased lymphocyte count in workers	BMCL = 8.2 mg/m3	300	3 × 10−2 mg/m3	USEPA (2003)
EU risk assessment report	Decreased lymphocyte count in workers	NOAEC = 3.2 mg/m3	None	3.2 mg/m3	European Chemicals Bureau (2008)
Cancer
USEPA	Leukemia in workers	Low-dose linearity utilizing maximum likelihood estimates	Not applicable	1 × 10−5 risk (1.3–4.5 µg/m3)	USEPA (2003)
European Commission Air Quality Standards				5 µg/m3	http://ec.europa.eu/environment/air/quality/standards.htm

BMCL = the 95% lower bound on the benchmark concentration. NOAEC = no observed adverse effect concentration.