In this article, we assemble and synthesize the available industrial hygiene data that describe exposure during the marine transport of benzene-containing products in the United States and abroad. A total of 25 studies were identified and summarized. The measured airborne concentrations of benzene on marine vessels were found to vary depending on several key factors, including the job task, vessel characteristics, cargo type, and sample type and duration. Despite the differences in sampling strategies and benzene content of the liquids being transported, personal time-weighted-average benzene air concentrations typically ranged from 0.2–2.0 ppm during closed loading and 2–10 ppm during open loading operations. Benzene exposures during these activities are likely due to specific short-term tasks, such as connecting and disconnecting hoses and tank gauging and sampling. Similar concentrations of benzene have been reported in the pump room during marine loading operations and during tank cleaning activities in various settings. When compared with contemporaneous occupational health standards, our review indicates that most activities performed on marine vessels from the 1970s to 1990s usually did not result in benzene exposures that exceeded these standards. The information and data presented here may be useful for quantitatively estimating or reconstructing historical exposures during the marine transport of benzene-containing cargo if details about individual's work histories in the maritime industry are available.
ACKNOWLEDGMENT
This work was funded by ExxonMobil. ExxonMobil has been involved in supporting research to understand the health effects of benzene for many years and has been involved in benzene-related litigations.
Notes
A Reported as wt% (Note: wt% can be converted to vol% using a default value of approximately 0.8 g/mL for the density of the products)
B For the MSD sheets, manufacturer's location is listed
C Market types with advanced requirements for emission control (US Cal LEV, US Cal LEV-II, ULEV, US EPA Tier 2, EURO 3, and EURO 4)
D Market types with stringent requirements for emission control (US Tier 0, US Tier 1, EURO 1, and EURO 2)
E Market types with no or minimal requirements for emission control
A One area sample taken for 5.5 hours, two personal samples taken for 45.5 hours.
B Sample type and duration are assumed by authors.
A Benzene concentrations in gasoline assumed to range from 1–5.0% from 1970 to 1985 and 0.5–2% from 1986 to 2000.
B Benzene concentrations in crude oil assumed to range from 0.5–1% from 1970 to 2000.
C Benzene concentrations in miscellaneous oil products assumed to range from 0.05–0.5% from 1970 to 2000.
D Benzene concentrations in benzene and benzene mixtures assumed to range from 50–100% from 1970 to 1985 and 25–100% from 1986 to 2000.