MALUKU, Indonesia — Just four months after Mongabay reported on a dramatic surge in diagnoses of respiratory illness near Indonesia’s second-largest nickel industrial estate, new data indicate that up to half the local population may have been exposed to unsafe levels of mercury — and one in three to harmful arsenic.

“This study is a serious warning of the long-term threat of heavy metal exposure, to both public health and environmental sustainability,” said Darmawati Darwis, a professor at Indonesia’s Tadulako University, which conducted the research in partnership with Nexus3, a Bali-based nonprofit.

The researchers from Nexus3 and Tadulako University took blood samples last year from 46 residents of Gemaf and Lelilef villages. These two villages are particularly close to the Weda Bay Industrial Estate, commonly known by its Indonesian acronym IWIP, on the island of Halmahera.

The results of those blood tests, which were published in April, showed 22 people (47%) had mercury levels above the safe limit of 9 micrograms per liter (µg/l) of blood — and the samples from 15 people (32%) exceeded the arsenic threshold of 12 µg/l.

“These findings emphasize the need for routine environmental and health monitoring, as well as law enforcement against polluting industries,” Darmawati said.

IWIP was established by Chinese mining conglomerates Huayou, Tsingshan and Zhenshi in 2018 as a smelting hub for the rapidly expanding nickel mining taking place on Halmahera Island. The IWIP site currently processes up to 30,000 metric tons of ferronickel ore per year, and is powered by 3,400 megawatts of purpose-built coal stations.

Halmahera’s IWIP is the production hub for the nickel industry in Indonesia’s Maluku region, while most smelting in the larger Sulawesi mining industry is carried out at the Morowali Industrial Estate, known as IMIP. Mongabay has reported extensively on the environmental and public health crises at both sites.

Since IWIP was established in 2018, the value of Indonesia’s exports of ferronickel have swelled by billions of dollars, providing much-needed revenues for a government elected to expand poorly funded health and education systems.

In 2024, Indonesia recorded production of 2.2 million metric tons of nickel, which was a majority of total global output last year.

Some projections of global demand indicate that compound growth at more than 5% per year will exceed expansion in supply as batteries and other new technologies support the global energy transition.

“Industrial activities in Weda, which are considered to be of strategic national importance, release and emit pollutants into the environment uncontrollably,” Nexus3 founder Yuyun Ismawati said. “The environmental and health risks linked with the IWIP area and its supporting industries pose a threat to the health of the community and workers.”

Poisoned chalice

The emerging reporting on the health consequences of Indonesia’s nickel mining industry follows well-documented evidence of community breakdown, amid deforestation and pollution of near-shore fisheries in parts of the Maluku and Sulawesi regions.

Mongabay reported earlier this year on destruction of nearshore fisheries in Gebe Island, where seven mining companies ship nickel ore to IWIP for processing via a polluting chemical treatment known as high-acid leaching.

The researchers from Nexus3 and Tadulako University also took samples of fish from two locations near IWIP, directly from fishers living in Gemaf village as well as from the traditional market in Lelilef village. All of the fish tested for heavy metals were caught in Weda Bay.

Four samples of anchovy, bream and snapper exceeded the maximum threshold of 2 milligrams of arsenic per kilogram of fish, which is set by Indonesia’s National Food and Drug Control Agency, known as BPOM. Seven other samples contained arsenic levels of 1-2 mg/kg, which can lead to negative health effects over longer-term consumption.

The researchers said concentration of arsenic in fish samples taken from Weda Bay was up to 20 times higher than in samples taken by the Research Center for Oceanography at the Indonesian Institutes of Sciences (LIPI) in 2007.

However, parts of local government contested the findings obtained by Nexus3 and Tadulako University, pointing to government tests of seawater in 2024 that showed safe levels in Weda Bay.

Rivani Abdurradjak, head of the environment department in Central Halmahera district, cited a 2021 regulation on environmental protections that codified acceptable parameters for heavy metal levels.

“Based on the results of laboratory tests, the values of important pollutant parameters are below the quality standards, so the quality of seawater is classified as good,” Rivani told Mongabay on June 2.

However, Fauji Momole, the acting head of the fisheries department for North Maluku province, said the provincial government could take stronger action if the government accepted the findings.

“If it’s confirmed that the fish caught are polluted, contaminated [with heavy metals], then in that area we may suspend fishing activities there,” Fauji said on May 29.

Melky Nahar, national lead of the Mining Advocacy Network, an Indonesian NGO known as Jatam, criticized the stance by some in government of contesting the findings without presenting evidence as corollary to dispute the results.

“Instead of welcoming these findings with caution and taking further steps to investigate, the provincial government hastily denied it — as if it were in panicked defense of its ‘employer’” Melky said.

Nexus3 and Tadulako University said regular monitoring should be established to track the levels of heavy metals in Weda Bay, particularly arsenic, chromium, mercury and nickel. Collection of blood samples should also be carried out to monitor public health.

“We encourage open data and collaboration of all parties to protect the community and ecosystem,” Tadulako University’s Darmawati said.

Public health crisis

Research in low- and middle-income countries has documented higher levels of heavy metal exposure in communities living alongside many mining areas.

Muhammad Aris at Khairun University told Mongabay that the condition of fish in Weda Bay had worsened owing to land reclamation for expansion of nickel processing, and to the greater volume of heavy metal pollution in the bay area.

The results published by Nexus3 and Tadulako University, Aris said, affirmed research he conducted in 2023 with Auriga Nusantara and the Indonesia Forum for the Environment (Walhi), two of Indonesia’s largest environmental advocacy groups.

Results of the 2023 study showed that two of six surveyed locations exceeded safe levels for mercury.

“The mangroves on the coast of Weda Bay have been converted for the expansion of the industrial area,” Aris said. “As a result their ecological function as a buffer zone has also been destroyed.”

Local fishers around Weda Bay report that many have stopped fishing as the availability of nearshore catch declines, making it increasingly difficult to recoup fuel costs, let alone achieve sustainable incomes.

“If heavy metals have been found in the human body, it means that accumulation in the marine food chain has occurred,” Aris said.

IWIP said in a statement that its mineral ore processing operations are governed by prevailing law and environmental standards.

“Every activity we carry out is based on the [environmental impact assessment] document that has been approved by the government, as well as based on applicable laws and regulations,” it said.

Banner image: Workers are visible at the Indonesia Weda Bay Industrial Park’s compound in Central Halmahera, North Maluku, Indonesia, Friday, June 7, 2024. Indonesia has been building out a vast industry for nickel. Image courtesy of AP Photo/Achmad Ibrahim.

This story was first published here in Indonesian on June 12, 2025.