A comprehensive investigation involving four accredited laboratories, 45 sampling points and hundreds of groundwater and soil samples identified no contamination of aluminum or the other 12 metals at issue. The company said the assessment also showed that a contamination of the nature indicated by the March data – which led to an operational suspension by the authorities – does not appear possible from SEMCORP’s processes and materials.
Debrecen, Hungary, August 26, 2026 – SEMCORP today published an open letter (read it here) setting out the findings of a large-scale investigation by independent accredited experts and laboratories into potential metals contamination in soil and groundwater at its Debrecen, Hungary manufacturing site. The investigation was launched after operations were suspended on June 24 following a laboratory report showing exceptionally high concentrations of several metals in groundwater samples collected in March.
According to the expert assessment, testing of hundreds of groundwater and soil samples from 45 sampling points across the site identified no contamination of aluminum or any of the other 12 metallic elements at issue. Furthermore, contamination of the nature and scope suggested by the March figures does not appear possible from SEMCORP’s processes or materials.
The assessment also determined that the March lab report presented total metal concentrations rather than dissolved metal concentrations, indicating that the high reported values likely reflected metal content naturally occurring in soil rather than a genuine contamination of dissolved metals in the groundwater. Under the applicable Hungarian regulations, dissolved concentrations are used to evaluate metals in groundwater, excluding metals contained in soil or other solid particles.
In addition to the letter, SEMCORP made lab reports containing groundwater test results available for review by the public. “We understand that the community has major environmental and health concerns about our operations, and we hope you’ll take a close look at the data,” the company said in its letter. “We want to assure you that we are committed to developing a complete, unbiased and accurate understanding of what happened. We’re also committed to do the hard work necessary to earn your trust, and we hope that sharing this information is a small step in that journey.”
Following the suspension of production activities in late June, SEMCORP commissioned a large-scale investigation designed to determine whether metals contamination was present and to understand the March laboratory results. The investigation also measured groundwater levels and flow, tested a condensate discharge identified as a possible source, conducted controlled leaching tests using the aluminum-containing ceramic materials used in production, compared sampling and testing protocols, reviewed historical baseline data and examined material movements and potential contamination points across the site. The complete assessment and laboratory data have been submitted to the environmental authority and other competent government bodies.
Under Annex 4 to Joint Decree 6/2009 (IV. 14.) KvVM–EüM–FVM, potential metals contamination in groundwater is assessed using dissolved metal concentrations, excluding metals contained in soil or other solid particles. Groundwater samples can contain soil particles, and soil naturally contains metals – particularly aluminum and iron. Testing total metal content counts the metals in those particles and can therefore produce values that are not comparable with the statutory dissolved metal thresholds.
Accredited experts concluded, and the lab that performed the sampling and testing in March also confirmed, that the March data reflected total metal concentrations, not dissolved metal concentrations, making it unsuitable for assessing dissolved metal contamination in groundwater under the applicable legal and technical standards. The pattern of metals reflected in the March data is itself highly indicative of the presence of soil particles in the tested groundwater samples: aluminum and iron were both elevated at the same sampling points, and their ratio was consistent across all ten points as well as with the metal composition found in soil samples from the site. Iron is not an input or output of SEMCORP’s manufacturing process.
In its letter, SEMCORP acknowledged that its team did not recognize this methodological issue when it first received and submitted the report and that the company should have investigated the results much sooner.
“One question that we’ve grappled with more than any other is the following: why did we not act with more urgency when we first received the highly concerning groundwater metals data in April?” the company said. “In retrospect, it seems likely that had we done the thorough investigation in April and May that we ultimately did over the last few weeks, we could have provided the assurance that government and community stakeholders needed much sooner.”
SEMCORP said that it has submitted to the environmental authority the complete dataset and expert assessment, and is continuing to follow the authority’s guidance on further site assessment activities. The company said that it was publishing the open letter and laboratory reports to enable experts, employees and members of the community to review the methods, sampling points and results directly.
The company expressed cautious optimism about its long-term prospects in Debrecen. “In light of the new findings, we genuinely hope that the authorities will give due consideration to our desire to promptly resume production activities in compliance with all applicable legal requirements,” the company said. “We believe the available information and data have clearly disproven the presumption that our operations had caused severe and widespread contamination of metals in groundwater.”
The company acknowledged that it has room for improvement in its compliance, transparency and community engagement. “We are looking deeply at the shortcomings in our leadership, management systems, compliance processes and work culture,” the company said. “We hope to have more to say about these and other topics very soon.”
The company said that it has already implemented organizational changes designed to ensure that major environmental, safety and compliance matters are escalated directly and promptly to group leadership. It is also examining further accountability measures, technical solutions to conserve water and reduce waste, and additional ways to disclose information about its operations and environmental impact.
SEMCORP is a global market leader in lithium-ion battery separator films. At its Hungarian site in Debrecen, the company produces advanced separator products that support the manufacture of up to 300,000 vehicles in Europe and the United States annually. SEMCORP employs more than 400 people in Hungary.
Contact: info@hu.semcorp.com