The No. 6 Naphtha Cracking Complex has started construction in Yunlin County in 1991, completed the construction of all 66 plants, including oil refineries, chemical manufacturing plants, and coal power plants in 2007, and begun fully operation afterwards. The objectives of this study were to conduct a preliminary assessment on health risks for residents living around this petrochemical complex and to propose a framework of a long-term environmental epidemiological study. Five specific tasks needed to be completed in this study: (1) to compile literatures of environmental and health research related to petrochemical industries; (2) to compile and analyze air and water quality data in the areas; (3) to collect health registry data for residents in the areas; (4) to assess the associations between environmental exposures and health outcomes; and (5) to plan a future epidemiological study for the county.
The methodologies of this study included: (1) searching international publications using Pubmed, Medline and Scopus, and domestic documents in graduate theses and governmental publications; (2) obtaining air quality data of PM10, CO, ozone, NOx, and SO2 during 1993-2007 from three Taiwan EPA operated monitoring stations, air concentration data of 56 VOCs during 2007-2008 from a PAMS station in Taisi, and ground water quality data from four Taiwan EPA operated monitoring stations near the petrochemical complex; (3) obtaining mortality and population data during 1971-2006 from DOH and Ministry of the Interior, cancer registry data during 1979- 2005 from DOH, and hospital admission and clinic visit data during 1996-2006 from the National Health Insurance Research Database, and then comparing the contrasts in mortality and cancer incidence rates between exposed areas and their geological comparison areas as well as between the periods before and after the complex started operation; (4) applying the hourly and annual VOC concentrations to calculate acute and chronic hazard index, HIa and HIc respectively, and cancer risks using the reference concentrations and unit risk values from the US and the California EPA; and (5) proposing an epidemiological study framework based on above risk assessment results.
The weather data showed that 58-71% of time in Taisi and 32-72% of time in Lunbei were downwind to the petrochemical complex annually, with October to March being the most likely downwind months while June to August being the least likely downwind months in a year. The environmental quality data were summarized as: “period before construction of the plants” before June 1995; “first operation period” during July 1995-August 2000; “second and third operation periods” during September 2000-July 2004; and “fourth operation period” during August 2004-June 2007. Our analyses found that ozone, PM10, and SO2 concentrations increased significantly since the first operation period in the exposed areas of the petrochemical complex. TVOC concentrations could reach above 200 ppb in the downwind areas of the petrochemical complex. TDS and TOC concentrations in groundwater increased consistently over the years.
Using year 1999 as the beginning of manufacturing processes with VOCs emissions from the complex, we summarized the standardized mortality and incidence rates of the townships within 10 km of the complex as: the periods of “pre-production ” for 1996-1998, “productionyear1-3” for 1999-2001, “productionyear4-6” for 2002-2004, “productionyear7-8” for 2005-2006 and compared them with their comparison townships. Our analyses found that: (1) total cancers and lung cancer standardized mortality rates in the productionyear4-6 period were significantly higher than those in the productionyear1-3 period in Taisi, and liver cancer standardized mortality rates in Taisi and Mailiao were significantly higher than their comparison townships before and during the production periods; (2) total cancers standardized incidence rates in Taisi, Dongshih, Lunbei, Mailiao and Sihhu during the production periods were significantly higher than those in the pre-production period. The standardized incidence rate for acute myeloid leukemia in the productionyear4-7 period was significantly higher than that in the productionyear1-3 period in Mailiao. The standardized incidence rates for liver cancer in Taisi and Mailiao and acute myeloid leukemia in Mailiao were significantly higher than those in their respective comparison townships during the production periods; (3) daily mean concentrations of NO2 and ozone in Taisi monitoring station and PM10 and NO2 in Lunbei monitoring station were significantly associated with daily hospital admissions of cardiovascular diseases of residents in their respective nearby townships in 2001-2006. The estimated life-time cancer risks of residents exposing to benzene were 3.30x10-6 (US EPA) or 4.35x10-5 (Ca EPA).
We recommend conducting a follow-up study to verify our findings by considering the following three suggestions: (1) follow up resident’s health outcomes prospectively in a cohort study; (2) assess resident’s detailed exposures to pollutant emissions from the petrochemical complex by Canister-GC/MS or FTIR method; (3) apply locally collected physical data to multi-media models to assess acute, chronic and cancer risks.
