TABLE 2. Agents Linked With Lymphohematopoietic Cancers and Their Presence in the Workplace.

Agent	Classification*			Cancer	Inhalation Unit Risk per μg/m3	Agent Use in Workplace
	IARC18	EPA19	NTP20			Process Agent	Process Byproduct	Quantified in Work Environment†
Ionizing radiation (x- and γ-radiation)	1		Known	Leukemia		Yes	Yes	Yes
Benzene	1	Carcinogenic	Known	Leukemia and others		No	No	No
1,3-Butadiene	1	Carcinogenic	Known	Leukemia and others		No	No	No
1,2-dichloroethane	2B	Likely carcinogenic	Reasonably anticipated	Lymphoma		No	Yes	No
Ethylene oxide	1			Lymphoma		No	No	No
Formaldehyde	1		Known	Leukemia	4.6 × 10−6 (33)	No	No	Yes§
Trichloroethylene	1	Carcinogenic	Reasonably anticipated	Lymphoma	2 × 10−6 (31)‡	Yes‖	No	No¶

*EPA classifications include carcinogenic to humans (carcinogenic) and likely to be carcinogenic to humans (likely carcinogenic). NTP classifications include known to be a human carcinogen (known) and reasonably anticipated to be a human carcinogen (reasonably anticipated).

†Agent was measured above the limits of detection by the company and/or authors.

‡This inhalation unit risk is only for lymphoma, not kidney cancers, liver cancers, and lymphoma combined.

§The 75th percentile of formaldehyde concentrations in the Line C Tin Plating SEG was estimated to be 0.0053 ppm, compared with the OSHA PEL of 0.75 ppm and ACGIH TLV of 0.3 ppm.

‖Use of trichloroethylene was discontinued in 1995.

¶All monitoring by the authors found the concentration of TCE to be below the limit of detection.

EPA, Environmental Protection Agency; IARC, International Agency for Research on Cancer; NTP, National Toxicology Program; TCE, trichloroethylene.