The Yunlin County Government has contracted National Taiwan University (NTU) to conduct a cohort study on air pollution and health among residents near the No. 6 Naphtha Cracker Complex, which is located in Miliao Township, Yunlin County, Taiwan since 2009. This is the third year of this series of three-year study and this report summarizes findings over the three years from July 2009 to July 2012. The study areas are 10 townships surrounding the petrochemical complex, including Baojhong, Taisi, Sihhu, Dongshih, Mailiao, Lunbei, Erlun, Citong, Yuanchang and Huwei. These townships are classified as three zones based on their distance to the petrochemical complex. Zone A includes Mailiao and Taisi which are within 10km radius of the petrochemical complex; Zone B includes Baojhong, Sihhu, Dongshih and Lunbei, townships which are located 10-20km radius of the petrochemical complex; and Zone C includes Erlun, Citong, Yuanchang and Huwei townships which are located within 20-30km radius from the petrochemical complex.
The NTU research team adopted a multiple-disciplinary approach to conduct this study, including environmental and biological monitoring, health examination, lung function tests and questionnaire survey. We have conducted a comprehensive literature reviews to update our understanding of environmental quality and health issues related to petrochemical industries. We also performed pollution analysis of existing air quality data of SO2, NO, NO2, NOx, O3, CO, and PM10 measured at three air monitoring stations operated by Taiwan Environmental Protection Administration from 1994-2011. We conducted new air measurements of 207 canister samples for volatile organic compounds (VOCs), 192 PM10 samples for heavy metals and 152 PM2.5 samples for polyaromatic hydrocarbons (PAHs) by Harvard impactor from 14 schools located in the 10 townships of the study areas. We have established an epidemiological cohort with a total of 3,230 residents who lived at those 10 towns and villages at least 5 years, and completed all survey questionnaires, lung function tests and health examinations. We completed biological monitoring of 2,176 residents’ urinary 1-hydroxypyren (1–OHP), which is a metabolite of PAHs, and 1,906 resident’s urinary heavy metals, and followed up 1,195 residents among the cohort. We successfully recruited a susceptible cohort of 132 pregnant women and 80 new-born babies by these women.
The main findings of environmental monitoring are: (1) The concentrations of SO2, NO, NO2, and NOx in Zone A were significantly elevated during the time period when the wind direction was from the No. 6 Naphtha Cracker Complex and the wind speed was higher than 3 m/s, and were increased chronologically with the expansion of manufacturing capacity of the No. 6 Naphtha Cracker Complex over the years. Furthermore, hourly SO2 concentrations have been above the US standard of 75 ppb and hourly NO2 concentrations have been above the hourly maximum levels predicted by dispersion models. (2) Several VOCs emitted either only or mainly from petrochemical industries can only be detected or measured at elevated concentrations at Zone A, especially during the time period when the wind direction was from the No. 6 Naphtha Cracker Complex. These VOCs include 1,3-Butadiene, Acrylonitrile (AN), Vinyl chloride, Ethane, 1,2-dichloro- (EDC), m/p/o-xylene, Propane, 2-methoxy-2-methyl- (MTBE) and Acetic acid, butyl ester (NBA). (3) Several metals and PAHs related either to coal-powered plants or petrochemical industries were measured at elevated concentrations in Zone A when the wind direction was from the No. 6 Naphtha Cracker Complex, including V, Sr, As, Ni and Cu, and Benzo[a]anthracene (B(a)A), Benzo[k]fluoranthene (B(k)F), Fluoranthene (Fl), Pyrene (Pyr) and Dibenz(a,h)anthracene (DBA). We also documented 21 major air pollution events between Decemner 2006 and June 2012 and conducted an in-depth analysis of air pollution after the big fire of May 12-13, 2011. We found that index air pollutants of the No. 6 Naphtha Cracker Complex, including ethylene, propylene, 1,3-butadiene, acetylnitrile, vinyl chloride, 1,2-dichloroethane and benzene, all showed exceedingly high levels in Taisi and Mailiao townships, the downwind areas of the complex, for one day. Potential cancer risks of residents attributable to exposures to vinyl chloride, benzene, and 1,3-butadiene, known human carcinogens, and crop damanges attributable to ethylene, a plant hormone, can not be overlooked in these two township.。
The basic characteristics of the established epidemiologic cohort are: age (46.4±21.8), gender (male 41.5%), smoker (9.9%), alcohol drinker (10.1%) and betel quid chewer (4.7%). The numbers of three Zones were 1016 residents in Zone A, 1007 residents in Zone B and 1207 residents in Zone C. The main finding of urinary metals is that urinary concentrations of V, Sr, As, Cd, for 636 residents in Zone A were higher than those for 1088 residents in Zone B and Zone C. The main finding of urinary I-OHP is that urinary concentrations of I-OHP for 524 residents in Zone A were higher than those for 1527 residents in Zone B and Zone C. The main findings of lung function are (1) FEF25-75% percent predicted and FEV1/FVC for 898 subjects in Zone A were lower than those for 1109 residents in Zone C. (2) FVC percent predicted and FEV1 percent predicted for 518 health residents who are non-smokers and have no history of disease in Zone A were lower than those for 551 health residents in Zone B. (3) Residents who lived in Zone A had lower PEF percent predicted than the other two Zones. The main findings of health examinations are: (1) The abnormal rates of BMI, platelet, BUN, GOT(AST), GPT(ALT), cholesterol(CHOL) and LDL-C for 989 residents in Zone A were significantly higher than those for 2174 subjects in Zone B and Zone C. (2) Multiple regression analysis shows that concentrations of BUN in blood were significantly correlated with urinary arsenic levels for 460 residents in Zone A.
The main conclusions of this three-year cohort study are: (1) The operation of the No. 6 Naphtha Cracker Complex has deteriorated air quality of both traditional (SO2 and NOx) and carcinogenic air pollutants (VOCs, metals, and PAHs) in the nearby areas, especially the radius of 10 km from the complex. (2) Residents who have lived within 10 km radius from the No. 6 Naphtha Cracker Complex for at least 5 years had elevated urinary levels of some index metals for petrochemical industries and 1-OHP. (3) Lung, liver, renal function, and blood and cardiovascular system were all compromised for residents who lived within 10 km radius from the No. 6 Naphtha Cracker Complex for at least 5 years.
We recommend strengthening pollution controls of all manufacturing plants in the No. 6 Naphtha Cracker Complex in order to reduce burdens of air pollution to the nearby communities. We also strongly recommend expanding and deepening this cohort study by increasing size of cohort and examining biomarkers in blood in order to early detect potential health effects for individuals who live near the No. 6 Naphtha Cracker Complex.