Seawater near Map Ta Phut has turned black and emits an abnormal smell — IEAT officials stated water quality "remains within normal levels," attributing the cause to seabed sediment. (Bangkok Post, 9 June 2026) This report examines whether that explanation holds against more than two decades of documented evidence.
Since 2003, PVC factories at Map Ta Phut Industrial Estate have discharged highly chlorinated wastewater, heavy metals, and carcinogens into the east canal — which flows directly to the Gulf of Thailand. Today, those factories are still operating and expanding capacity. Thailand still has no law requiring mandatory public disclosure of industrial pollution releases.
Taragraphies · กองบรรณาธิการEditorialมิถุนายน 2569June 2026อ้างอิง: Greenpeace Research Laboratories GRL-TN-09-2004Source: Greenpeace Research Laboratories GRL-TN-09-2004
Map Ta Phut Industrial Estate in Rayong Province spans 166 km², housing 151 facilities including oil refineries, petrochemical plants, coal-fired power stations, and steel mills. Among them, two companies produce polyvinyl chloride (PVC) — one of the world's most widely used plastics: Vinythai and Thai Plastic & Chemicals (TPC).
Both factories sit along the east canal, which collects industrial wastewater from multiple facilities and drains into the Gulf of Thailand. In May 2003, Greenpeace Research Laboratories collected wastewater and sediment samples from five discharge points at both facilities and analysed them at the University of Exeter, UK. The results were alarming.
Analysis identified chlorinated volatile organic compounds (VOCs) in wastewater from both facilities. Most alarming was 1,2-dichloroethane (EDC) — the chemical intermediate in VCM production — at 250 µg/l in TPC's main discharge pipe. This exceeds the US EPA maximum daily limit for equivalent facilities (211 µg/l) by 1.2 times, and the US monthly average limit by 3.7 times.
Canal sediment near TPC discharges contained persistent organochlorines that bioaccumulate in the food chain: octachlorostyrene, hexachlorobenzene (HCB), and multiple chlorinated benzenes. Although absent from wastewater collected that day, their presence in sediment indicates prior releases — and that canal continuously drains to the Gulf.
"The discharge of organochlorines is not specifically addressed under Thai industrial effluent legislation, despite the Thai National Chemicals Management Profile listing organochlorine compounds as 'specific chemicals creating concern.'"
— Greenpeace Research Laboratories, GRL-TN-09-2004
Vinythai now operates as AGC Vinythai, still producing EDC, VCM, PVC and chlor-alkali products at Map Ta Phut. The company is actively expanding its Caustic Soda and Chlorine plants — meaning more chlorine production capacity and a higher potential for chlorinated by-product generation.
Meanwhile, the Map Ta Phut Industrial Port is undergoing a 55.4-billion-baht third expansion, reclaiming 395 additional acres from the sea. Small-boat fisherfolk report having to travel 5 kilometres further offshore just to maintain their previous catch volumes.
Research published in Marine Pollution Bulletin (2019) found that contamination from Map Ta Phut reaches coastal waters through submarine groundwater discharge (SGD) — contaminated groundwater seeping directly into the sea beneath the sediment floor, even when pipe discharges are stopped. Zinc, manganese, lead, and iron in groundwater exceeded safety standards by 10–150 times, even after Map Ta Phut was officially designated a "pollution control zone."
Seawater near Map Ta Phut turns black and foul-smelling — IEAT states "within normal levels" without disclosing per-factory pollution data (Bangkok Post, 9 June 2026)
ช่องว่างความรับผิดชอบ · Accountability GapAccountability Gap
ทำไมเราถึงยังไม่รู้?
Why Are We Still in the Dark?
คำตอบของ กนอ. ต่อเหตุการณ์น้ำทะเลดำมิถุนายน 2569 ไม่ต่างจากรูปแบบที่เกิดซ้ำมาสองทศวรรษ: ยืนยันว่า "อยู่ในเกณฑ์" โดยไม่เปิดเผยข้อมูลการปล่อยสารพิษของโรงงานรายแห่ง นี่คือผลโดยตรงของการที่ประเทศไทยไม่มีกฎหมาย PRTR (Pollutant Release and Transfer Register) ที่มีผลบังคับใช้
IEAT's response to June 2026's black seawater follows a pattern repeated over two decades: declare "within limits" without releasing per-factory discharge data. This is the direct consequence of Thailand having no enforceable PRTR (Pollutant Release and Transfer Register) law.
In countries with PRTR systems — Japan, South Korea, the US, all OECD members — industrial facilities must publicly report annual quantities of each toxic substance released to water, air, and soil. Communities along the Gulf of Thailand would be able to look up immediately how much EDC, VCM, or HCB AGC Vinythai discharged last year. In Thailand, that data simply does not exist.
ไทยอยู่ระหว่างกระบวนการสมัครสมาชิก OECD และต้องผ่านการตรวจสอบมาตรฐานกว่า 240 ข้อ หนึ่งในนั้นคือ OECD Council Recommendation on PRTR (C(96)41) ที่กำหนดให้ประเทศสมาชิกต้องมีระบบฐานข้อมูลการปล่อยมลพิษที่เข้าถึงได้สาธารณะ
Thailand is in the process of applying for OECD membership and must pass review against over 240 standards. Among them: OECD Council Recommendation on PRTR (C(96)41), which requires member states to maintain a publicly accessible pollution release and transfer database.
Map Ta Phut is the clearest proof: no PRTR law means no data, no accountability, and no protection. If Thailand intends to demonstrate that its OECD application is more than transition aesthetics — Map Ta Phut is the first, unavoidable test case.
ข้อเรียกร้อง · DemandsDemands
● ข้อเรียกร้องต่อรัฐบาลและหน่วยงานที่เกี่ยวข้อง● Demands to government and relevant agencies
Black water, foul smell, disappearing fish, sick communities — these are not new phenomena. They have recurred for 20 years while data was withheld and legislation was delayed.
Taragraphies demands immediate action on the following three points:
IEAT and the Department of Industrial Works must immediately disclose per-factory pollution release data — five years of retrospective data for all Map Ta Phut facilities, including AGC Vinythai and TPC, in downloadable format, covering EDC, VCM, HCB, Zinc, Mercury and all substances identified in GRL-TN-09-2004. This does not require PRTR legislation to implement.
Deadline: 90 days
An independent seawater quality investigation must be conducted at Map Ta Phut — by scientists with no IEAT affiliation and no industry funding, covering VOCs, chlorinated benzenes, heavy metals, and phthalates. Results must be publicly released within 30 days of receipt.
Deadline: 60 days
Parliament must pass a PRTR Act within the 2026 legislative session — with provisions covering all chlorinated compounds and POPs, enforceable penalties, and explicit linkage to the OECD Accession process as a measurable condition. Taragraphies will not accept an Initial Memorandum that contains no PRTR evidence.
Deadline: 2026 session
These three demands are not proposals, not requests for cooperation, and not recommendations — they are the minimum acceptable baseline in a situation where contamination evidence has accumulated for 20 years while state mechanisms have provided far stronger protection to companies than to communities.
Thailand is a signatory to the Stockholm Convention requiring elimination of POPs and their sources. Vinythai and TPC affirm in public documents that they maintain environmental policies — but policies on paper and realities in canal sediment do not align. That discrepancy must be resolved with public data, not press statements.
Black water, a smell residents cannot ignore, fish disappearing from the bay — these are not natural phenomena explainable by sediment. They are the accumulation of what we have chosen not to look at, not to measure, and not to disclose.
— บทบรรณาธิการ taragraphies · มิถุนายน 2569taragraphies editorial · June 2026
แหล่งอ้างอิงหลักSources
Brigden, K., Labunska, I. & Santillo, D. (2004). Investigation of chemicals released by the Vinythai and TPC PVC manufacturing facilities, Map Ta Phut Industrial Estate. GRL-TN-09-2004. Greenpeace Research Laboratories, University of Exeter.
Leanpolchareanchai, J. et al. (2019). Tracing underground sources of pollution to coastal waters off Map Ta Phut. Marine Pollution Bulletin 148. DOI:10.1016/j.marpolbul.2019.07.066
EarthRights International (2024, July 16). Small-boat fishing is collapsing. earthrights.org
Bangkok Post (2026, June 9). Dark, smelly waters linked to sediment. bangkokpost.com
World Resources Institute (2017). Excell & Moses: Thirsting for Justice.
Pollution Control Department, Thailand (2009). Environmental Management Plan, Map Ta Phut Pollution Control Zone.
OECD (1996). Council Recommendation on PRTR. C(96)41/FINAL.
Global Community Monitor, in Tanyanont & Vichit-Vadakan (2012): VOCs at Map Ta Phut exceed developed-nation safety standards 60–3,000×.
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