Abstract:

We performed laboratory measurements to record concentration of different volatile organic compounds (VOCs) emitted from a crude oil slick before and after premixing with dispersant. We input these concentrations into a health risk assessment model to estimate the cancer risk and hazard quotients based on USEPA-designated measures and reference concentrations. We targeted the health risk assessment of cleanup workers or residents nearby. Based on the results, the cancer risk of exposure to toluene and benzene reduced from 74 and 57 excess lifetime cancer cases per million for one hour per day of exposure continuing for 3 months to 66 and 37 (11% lower) excess lifetime cancer cases per million. Dispersant addition was effective in emission reduction of the lighter VOCs (up to 30% lower emission rate). However, hazard quotients of the non-carcinogenic VOCs even after dispersant addition were 2 to 3 orders of magnitude greater than 1 meaning that there are serious concerns about exposure to these VOCs.

Suggested Citation:

Nima Afshar-Mohajer. 2018. Health risk assessment of inhaled oil spill emissions with and without adding dispersant (due to volatile organic compounds). Distributed by: GRIIDC, Harte Research Institute, Texas A&M University–Corpus Christi. doi:10.7266/N7RX99PN

Publications:

Afshar-Mohajer, N., Fox, M. A., & Koehler, K. (2019). The human health risk estimation of inhaled oil spill emissions with and without adding dispersant. Science of The Total Environment, 654, 924–932. doi:10.1016/j.scitotenv.2018.11.110

Purpose:

There is some evidence that dispersion of the crude oil decreased emission rate of the VOCs but increased emission rates of the fine PM that carry the toxic compounds. In this study, the cancer risk, and non-cancer hazard of the detected VOCs based on steady-state concentrations during pilot-scale breaking waves, with and without adding dispersant onto the oil slick were estimated.

Data Parameters and Units:

Concentrations volatile organic compounds (mg/m3 and ppm); Concentration (ppm); Potency factor (mg/kg/day)-1; Hazard quotient (unit-less); Daily Dose (mg/day), hr per day exposure, life dose, reference dose, Breathing rate (m^3/hr), Body weight (kg)

Methods:

A closed acrylic wave tank (6 m x 0.6 m x 0.3 m) was used for lab experiments. Tanks were filled with artificial seawater (33 ppt). A large wave was generated with a paddle frequency of 0.75 Hz and a stroke length of 0.53m. The result wave had a velocity of 1.25 m/s, height of 0.29, intrusion of 0.17 mm and turbulent energy dissipation rate of 2.40 m^2/s^3. The waves were generated every 10 seconds for 15 minutes. 900 mL of Louisiana Light Sweet crude oil or crude oil-dispersant mixture with a dispersant to oil ratio of 1:25 was poured over the water to create a 0.5 mm thick slick. Air was sampled after 15 minutes of run and then sent to the lab for analysis. Each experiment was run twice. The VOC concentrations were estimated from the GC/MS analysis on the sampled air on top of a tank simulating breaking waves. Toxicity metrics reported in this table are extracted from the World Health Organization (WHO), the Integrated Risk Information System under United States Environmental Protection Agency (USEPA – IRIS), the Agency for Toxic Substances and Disease Registry under United States Department of Health and Human Services (USHHS – ATSDR), and Office of Environmental Health Hazard Assessment (OEHHA) under California Environmental Protection Agency (Cal/EPA). Health risk assessment used: a risk (in this case for carcinogens) or a hazard (in the case for non-carcinogens) is equal to the delivered dose time potency factor or reference concentration. Potency factors and reference concentrations are determined and listed by the USEPA. The delivered dose is simply calculated by knowing the concentrations (as reported in the Excel files of Crude oil only and oil-dispersant mixtures) times the amount of air a human being inhaled in a certain time frame.

Instruments:

Gas chromatography and mass spectrometery (GC/MS) and handheld photoionization device (PID): MiniRAE 3000 by Honeywell Inc.

Individual Files: