The reciprocal calculation procedure for setting occupational exposure limits for hydrocarbon solvents: An update

Figures & data

Table 1. Current recommended group guidance/substance-specific values for the RCP calculation.^a

Constituent Grouping	UK^[18] (mg/m^3)	HSPA/ACGIH^[19,25] (mg/m^3)	Germany^[24] (mg/m^3)
C5–C6 alkanes (excluding n-hexane)	1800	1500	1500
C7–C8 alkanes	1200	1500	1500
C5–C6 cycloalkanes	1800	1500	1500
C7–C8 cycloalkanes	800	1500	1500
C7–C8 aromatics	500	200	200
C9–C15 alkanes	1200	1200	600
C9–C15 cycloalkanes	800	1200	600
C9–C15 aromatics	500	100	100

^a Current value. Note that national advice requires that exposures to constituents not exceed national recommendations.

Table 2. Proposed group guidance/substance-specific recommendations for the RCP calculation.

Hydrocarbon Solvent Constituent Group	Proposed Group Guidance/Substance Specific Value (mg/m^3)	Constituents with ACGIH TLVs (mg/m^3)
C5–C8 Aliphatics	1400	Pentane (all isomers) – 2950
		Hexane (all isomers)^a– 1760
		Heptane (all isomers) – 1640
		Octane (all isomers) – 1401
		Cyclopentane – 1720
		Cyclohexane – 350
		Methylcyclohexane – 1610
C9–C15 Aliphatics^b	1050	Nonane – 1050
C7–C8 Aromatics^c	NA	Toluene – 75
		Xylene (all isomers) – 434
		Ethylbenzene – 87
C9–C15 Aromatics^d	100	Trimethylbenzene isomers – 123
		Cumene – 246
		Indene – 24 Biphenyl – 1.3
Substances with Substance Specific Values
n-hexane	176	176
Naphthalene	50	50
Diethyl/Triethyl benzene	28	No value

^a Except n-hexane.

^b Because of their very low vapor pressures, constituents with carbon numbers > C15 do not contribute significantly to overall vapor exposure. However, the potential for aerosol exposure must be considered.

^c Group eliminated in favor of adopting existing national regulatory values as SSVs.

^d Because of their higher boiling points, aromatics with more than two rings are not commonly found at more than trace levels in hydrocarbon solvents.

Table 3. RCP OEL calculation for regular white spirit.

Constituent	RCP Hydrocarbon Group	GGV or SSV (mg/m^3)	Liquid Mass Fraction (Fra)^a	Reciprocal Calculation^b
C8 aliphatics	C5-C8 aliphatics	1400	0.02	1.43 × 10^−5
C9 aliphatics	C9-C15 aliphatics	1050	0.14	0.00013
C10–C15 aliphatics	C9-C15 aliphatics	1050	0.652	0.00062
Toluene	NA	75	0.001	1.333 × 10^−5
Xylene	NA	434	0.006	1.383 × 10^−5
C9 trimethylbenzene isomers	C9-C15 aromatics	100	0.18	0.0018
Naphthalene	NA	52	0.006	0.0001154
Diethylbenzenes	NA	28	0.015	0.000536
Sum				0.003243

^a Mass fraction in liquid phase divided by 100%. NA = not available

^b Fr_a/GGV or Fr_a/SSV

Table 4. Composition/RCP OEL calculation of VM&P Naphtha.^[12]

Constituent	Weight (%)	RCP Hydrocarbon Group	GGV or SSV (mg/m^3)	Reciprocal Calculation^a
C5–C8 alkanes	26.0	C5–C8 aliphatics	1400	0.000186
C5–C8 cycloalkanes	21.2	C5–C8 aliphatics	1400	0.000151
C9–C11 alkanes	29.4	C9–C15 aliphatics	1050	0.00028
C9 cycloalkanes	7.8	C9–C15 aliphatics	1050	7.43 × 10^−5
C10 cycloalkanes	3.3	C9–C15 aliphatics	1050	3.14 × 10^−5
C11 cycloalkanes	0.4	C9–C15 aliphatics	1050	3.81 × 10^−6
C7 alkylbenzenes	1.6	Toluene	75	0.000213
C8 alkylbenzenes	5.9	Xylene	434	0.000136
C9–C10 alkylbenzenes	4.2	C9–C15 aromatics	100	0.00042
Sum				0.001496

^a Fr_a/GGV or Fr_a/SSV

HSE: “Occupational Exposure Limits, 1995.” London: Health and Safety Executive, 1995.

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TRGS: TRGS 900 Workplace exposure limits in technical rule for hazardous substances, Federal Institute for Occupational Safety and Health (BAuA). Germany, 2017.

 Google Scholar

Carpenter, C.P., E.R. Kinkead, D.L. Geary, L.J. Sullivan, and J.M. King: Petroleum hydrocarbon toxicity studies: II. Animal and human response to vapors of Varnish Makers' and Painters' Naphtha. Toxicol. Appl. Pharmacol. 32(2):263–281 (1975).

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