Residents living near the Sixth Naphtha Cracker Complex report that they often smell something "sour," "sticky" and "thick," and today the mystery of the sour smell has finally been solved! The National Taiwan University College of Public Health points out that the source of the sour smell is the pungent "formic acid"; project leader Chiu Chia-pin, project assistant professor at the Institute of Occupational Medicine and Industrial Hygiene at the NTU College of Public Health, says that since formic acid has already been detected, the declared carcinogen "formaldehyde" may be produced alongside it, "and that is what worries us most."

So where does the formic acid come from? "Ethylene plus ozone turns into formic acid plus formaldehyde." The research team points the finger at the Sixth Naphtha Cracker Complex, whose main raw material is "ethylene."

Formaldehyde (methanal) is a colorless gas with a pungent odor that irritates the eyes and throat; at higher concentrations it can cause nausea, vomiting, coughing, chest tightness, asthma and even emphysema and other symptoms. It is mainly used to produce industrial resins, such as particleboard and coatings. In 2011, the U.S. National Toxicology Program described formaldehyde as a "known human carcinogen."

NTU College of Public Health: Pungent formic acid detected, fears it may come with the carcinogen "formaldehyde"

From October 20 to December 21 last year, the NTU College of Public Health used the latest "gas and aerosol composition monitor" to continuously monitor the air at Dingzhuang Elementary School in Dingzhuang Village hour by hour for 1,500 hours. Chiu Chia-pin says the monitoring results found that during those 1,500 hours, in 6% of the monitoring time, that is more than 90 hours, the formic acid concentration exceeded 24 ppb. "Once formic acid exceeds 24 ppb, you can smell the pungent sour odor."

Moreover, the monitoring peaks generally fell between 10 a.m. and 4 p.m. "So we infer that the high concentrations of formic acid gas are what make residents near the Sixth Naphtha Cracker Complex often smell that 'sour,' 'sticky,' 'thick' odor."

But what effect does "formic acid" actually have on the human body? "For now we can only say that formic acid is a gas with a pungent odor, but there is not yet enough research to prove what harm formic acid causes to the human body," Chiu Chia-pin explains; what worries the research team most at present is that since formic acid has already been detected, the declared carcinogen "formaldehyde" may be produced alongside it. "Although we don't yet have equipment that can measure formaldehyde, this is what we are worried about."

Residents of Taixi Village and Dingzhuang Village in Dacheng Township have elevated urine heavy metal concentrations

In addition to monitoring gas and aerosol composition, from September 11 to 26, 2014, the research team also used "continuous heavy metal monitoring equipment" to monitor toxic substances in the ambient air of Dacheng Township. During that period, a total of 20 kinds of heavy metals emitted by the petrochemical industry were detected, most of which overlapped with the heavy metals measured in residents' urine.

The research successively found that residents of Taixi Village and Dingzhuang Village in Dacheng Township, which are closer to the Sixth Naphtha Cracker Complex, had higher urine concentrations of heavy metals such as vanadium, chromium, manganese, nickel, copper, arsenic, cadmium, thallium and lead than residents of Zhutang Township, which is far from the Sixth Naphtha Cracker Complex.

After the Sixth Naphtha Cracker Complex began operating, cancer incidence among Taixi Village residents rose markedly

From 2014 to 2016, the team of Professor Chan Chang-chuan at the Institute of Occupational Medicine and Industrial Hygiene, NTU College of Public Health, carried out the "Changhua Area Environmental Epidemiology Study" research project. Over three years, it completed analyses of industrial toxicant levels in the bodies of 1,934 residents with an average age of about 59, as well as calculations of changes in cancer incidence.

The research team further points out that in the 9 years after the Sixth Naphtha Cracker Complex began operating, that is, between 1999 and 2007, for every 1,000 people each year, 1 person developed all cancers; but by 10 to 16 years after it began operating, that is, from 2008 to 2014, this climbed to 8.44 people per 1,000 per year developing all cancers. "The incidence of all cancers rose markedly."

Taking into account that cancer requires a latency period of about 9 years, and after excluding factors such as age, sex, smoking, drinking, betel nut chewing, hepatitis C and having worked at the Sixth Naphtha Cracker Complex, the research team points out that from the 10th year after the complex began operating, the cancer risk of Taixi Village residents was 2.66 times that of residents of other villages in Dacheng Township and 2.29 times that of residents of Zhutang Township. "The results show that cancer incidence among Taixi Village residents is significantly associated with the operation of the Sixth Naphtha Cracker Complex."

Research team: Monitoring formaldehyde requires suitable equipment, which is currently unavailable

Chiu Chia-pin says that although the "Changhua Area Environmental Epidemiology Study" research project has temporarily come to an end, monitoring of formic acid concentrations in Taixi Village will continue; in addition, an interdisciplinary research project has now been applied for from the Ministry of Science and Technology, and in the future the relationship between children's respiratory diseases and the local environment may be studied in the Yunlin and Changhua areas.

As for the irritant gas formic acid measured this time, the research team worries that the carcinogenic substance "formaldehyde" may exist alongside it. Is it possible to further monitor formaldehyde? Chiu Chia-pin says, "For the time being there is still no way." Monitoring formaldehyde still requires finding suitable equipment before it can be done, and in the short term this may be difficult.

Less than 10 km from the Sixth Naphtha Cracker Complex, urine heavy metal concentrations of Taixi Village residents in Changhua exceed the standard by 2.4 times

Our Island / The Forgotten Taixi Village