Evaluation of Health Hazards in Secondary Battery Industry Workers Focusing on Chemical Burns

Abstract

The rapid growth of the secondary battery industry for electric vehicles has introduced underexplored occupational hazards. This study investigated the characteristics and causes of skin disorders among workers in lithium production and battery recycling facilities to identify preventive measures. In 2024, walkthrough surveys and health interviews were conducted with 127 male workers at two newly established plants selected based on visible symptoms or involvement in high-risk processes. Skin lesions were reported by 38.8% of workers in the lithium production plant, mainly chemical burns caused by lithium hydroxide dust reacting with sweat to form a strong alkali, with the wrist being the most frequently affected site. In the recycling plant, 35.0% experienced skin lesions, predominantly contact dermatitis associated with exposure to metal dusts and acids. These findings indicate substantial risks of chemical burns and contact dermatitis, highlighting the need for improved protective equipment, ventilation, and safety management in this expanding industry.

1. Introduction

The global transition toward electric vehicles (EVs) and renewable energy storage systems, has positioned the secondary battery industry as a critical pillar in efforts to mitigate climate change. Lithium-ion batteries, in particular, are widely regarded as environmentally friendly because they produce no direct greenhouse gas emissions during operation. However, while the downstream environmental benefits of electric mobility are well recognized, considerably less attention has been paid to the occupational health risks associated with the manufacturing and recycling of secondary batteries [[1], [2], [3], [4]].

Secondary batteries, including lithium nickel cobalt manganese oxide (NCM; Li[Ni,Co,Mn]O₂) batteries, are rechargeable energy storage systems that rely on a variety of hazardous metals and chemicals during production. Manufacturing processes commonly involve lithium, nickel, cobalt, and manganese compounds, as well as corrosive chemicals such as sulfuric acid, hydrofluoric acid, and sodium hydroxide [5]. These substances are associated with well-documented adverse effects on the skin. Excessive lithium exposure can cause corrosive skin injuries [6]. Nickel and cobalt are well-known skin sensitizers that commonly cause allergic contact dermatitis [7]. Strong acids and bases can cause severe chemical burns [8].

Despite the rapid growth of the secondary battery industry, systematic research on occupational exposure and worker health outcomes remains limited. Existing studies have largely focused on battery performance, materials development, and environmental sustainability, leaving a critical gap in understanding workplace hazards and health risks faced by workers. To address this gap and to proactively identify emerging occupational hazards, the Occupational Safety and Health Research Institute (OSHRI), affiliated with the Republic of Korea Occupational Safety and Health Agency (KOSHA), conducted a comprehensive exposure survey of the secondary battery industry [5,9].

During this investigation, a cluster of skin disorders was reported among workers at a cathode active material manufacturing facility. Field investigations and health interviews conducted by the OSHRI team revealed multiple cases of chemical burns and contact dermatitis associated with exposure to lithium, nickel, cobalt, and manganese compounds in the cathode active material production plants [6,9]. Among these substances, lithium hydroxide was identified as a primary causative agent due to its strong alkaline reactivity.

Following these findings, additional investigations were conducted at a lithium production plant and a secondary battery recycling plant, where workers are similarly exposed to lithium-containing materials. This study describes the characteristics of chemical burns and contact dermatitis observed in these facilities and discusses practical prevention strategies to enhance occupational health protection in this rapidly expanding industrial sector.

2. Methods

2.1. Manufacturing processes and occupational health hazards

Field investigations were conducted in 2024 through site visits to two facilities: a lithium production plant and a secondary battery recycling plant (Table 1). These facilities were newly established factories that underwent a trial operation period and commenced full-scale production in 2023. During these visits, walkthrough surveys of the production areas were performed to identify potential occupational exposure risks.

Table 1.

Characteristics of workers underwent a health interview

Factory	Employer	Employees	Interviewees
		n	n	Age		Work duration(month)
				Mean	SD	Mean	SD
Lithium production	Company	191	47	29	8	13	13
	Subcontractor	46	13	36	10	5	3
Secondary battery recycling	Company	177	43	29	5	22	4
	Subcontractor	76	24	30	6	16	6
Total		490	127	30	8	15	11

N, number of workers; SD, standard deviation.

With respect to manufacturing processes, lithium production can be divided into upstream and downstream processes. The upstream process involves the conversion of spodumene ore to lithium sulfate solution through high-temperature treatment and sulfuric acid leaching. The downstream process consists of refining and converting lithium sulfate into lithium hydroxide powder using alkaline reagents such as sodium hydroxide. Workers in the upstream and downstream processes can be classified into boardmen, who operate and monitor the production process in the control room, and fieldmen, who are directly involved in production activities on the shop floor. While exposure to liquid chemicals is generally limited under enclosed operating conditions, workers may be exposed to lithium hydroxide particulates during product finishing tasks, particularly during drying and packaging [5].

The battery recycling industry recovers valuable metals, including lithium, nickel, cobalt, and manganese, from waste lithium-ion batteries. Black powder (BP) is a mixture of metal compounds and graphite, and workers may be exposed to metal-containing particulate dust throughout BP handling processes. Metal recovery is primarily achieved through sulfuric acid leaching, followed by solvent extraction and crystallization. Copper, manganese, cobalt, and nickel are sequentially separated from the leachate by solvent extraction. In the crystallization process, manganese, cobalt, and nickel are recovered as sulfate crystals through evaporation, filtration, and drying, while the lithium-containing raffinate is further treated to remove impurities and produce battery-grade lithium carbonate during the lithium recovery process [5]. During secondary battery recycling processes, workers may be exposed to sulfuric acid and metal-containing dusts, including lithium carbonate and metal sulfates of nickel, cobalt, and manganese.

2.2. Selection of workers and in-depth health interviews

Workers selected for interviews either had visible skin lesions or were engaged in high-risk processes. At each factory, the occupational health manager identified workers for interviews based on their symptoms and job-related exposure.

All selected workers underwent interviews to assess occupational exposure histories, including specific tasks performed, materials handled, and use of personal protective equipment, as well as the presence and progression of work-related health symptoms. Semi-structured clinical interviews were conducted on site by an occupational and environmental medicine specialist, with a focus on identifying dermatological symptoms potentially associated with chemical exposure.

2.3. Definition and assessment of chemical burns and contact dermatitis

A chemical burn is an acute, severe irritation reaction in which the cells are irreversibly damaged, resulting in a loss of tissue viability [10]. For example, lithium hydroxide dust can react with moisture in sweat to form strongly alkaline compounds, leading to chemical burns on exposed skin.

Contact dermatitis is classified into irritant and allergic types [7]. Approximately 80% of occupational contact dermatitis cases are irritant in nature. Irritant contact dermatitis typically presents as an immediate reaction following exposure to irritating substances and is characterized by erythema, pruritus, and edema. In contrast, allergic contact dermatitis occurs after prior sensitization, with symptoms such as pruritic rashes developing after a delayed period following exposure. Contact dermatitis may be caused by strong irritants, including sulfuric acid and sodium hydroxide, which can produce rapid skin reactions upon contact. Prompt washing of the affected area may limit the condition to contact dermatitis; however, delayed decontamination or prolonged exposure may result in progression to chemical burns. For instance, lithium carbonate forms weakly alkaline solutions upon contact with moisture and may cause contact dermatitis, but prolonged exposure in confined environments, such as inside gloves, can lead to chemical burns.

3. Results

Health interviews were conducted in 2024 with 127 male workers—60 from the lithium production plant and 67 from the secondary battery recycling plant (Table 1). Both plants began full-scale production in 2023, so most workers involved in manufacturing processes were relatively early in their employment, with a mean age of 30 years and an average work duration of 15 months. Workers employed directly by the lithium production and battery recycling companies were slightly younger and had longer work durations than subcontractor workers.

As shown in Table 2, experiences of chemical burns or contact dermatitis varied by factory, employer type, and work process. In the lithium production factory, 26 of 67 workers (38.8%) reported experiencing chemical burns or contact dermatitis, with a higher proportion observed among company-employed workers in downstream processes (62.5%). The primary health concern was chemical burns, identified in 24 workers, accounting for 92.3% of those who reported skin lesions. In the lithium production factory, lithium hydroxide dust was the main causative agent. Hot and humid summer conditions, combined with the use of protective equipment such as helmets and masks, led to substantial sweating. Contact of lithium hydroxide dust with moist skin readily resulted in chemical burns due to the formation of a strong base. The most commonly affected site was the wrist (65.4%), due to lithium hydroxide dust penetrating between the protective suit and gloves, followed by the upper arm and hand (Fig. 1).

Table 2.

Experience of chemical burns or contact dermatitis among workers by factory and work process

Factory	Employer	Process	Skin lesion
			n	Interviewee	%
Lithium production	Company	Upstream	4	20	20.0
		Downstream	15	24	62.5
		Maintenance	5	11	45.5
	Subcontractor	Packaging/cleaning	0	6	0
		Forklift/loader	2	6	33.3
	Total		26	67	38.8
Battery recycling	Company	Leaching	1	7	14.3
		Solvent extraction	6	15	40.0
		Crystallization	5	11	45.5
		Lithium recovery	5	14	35.7
	Subcontractor	Leaching/filter press	2	4	50.0
		Crystallization/packaging	2	6	33.3
		Lithium/packaging	0	3	0.0
	Total		21	60	35.0

Fig. 1.

Partially healed chemical burn on the wrist.

In the battery recycling factory, 21 of 60 workers (35.0%) reported experiencing skin lesions. A higher proportion was observed among company-employed workers in the crystallization process (45.5%), as well as among subcontractor workers involved in leaching and filter press operations (50%) (Table 2). The primary skin lesion observed was contact dermatitis, with some cases suspected to be chemical burns; however, distinguishing between these conditions was not always possible. In the secondary battery recycling facility, contact dermatitis was primarily associated with exposure to metal dusts, including lithium carbonate, nickel sulfate, cobalt sulfate, and manganese sulfate. Notably, 11 of the 21 workers (52.4%) with skin lesions explicitly identified exposure to these metal dusts as the cause. In the crystallization process, nickel sulfate, cobalt sulfate, and manganese sulfate were the primary causes of contact dermatitis, whereas lithium carbonate was the main causative agent in the lithium recovery process. These compounds appeared to have a lower potential to induce skin lesions compared with lithium hydroxide, likely because they form only weak acids or bases. Nevertheless, prolonged or occluded contact may still result in chemical burns. Nickel and cobalt are well-known allergens and can induce allergic contact dermatitis in susceptible workers [7]. Accordingly, several workers were suspected of having allergic contact dermatitis; however, no confirmatory diagnostic evaluations, such as patch testing, were performed during the health interviews.

Workers in both facilities who were exposed to strong acids (e.g., sulfuric acid) and strong bases (e.g., sodium hydroxide) experienced irritation of the mucous membranes, including the eyes, nose, and pharynx. However, the occurrence of chemical burns associated with these agents was lower than anticipated, possibly reflecting workers' heightened awareness of the associated risks, and prompt irrigation of affected areas following contact. Although direct skin contact with liquid sulfuric acid has the potential to induce chemical burns, immediate irrigation appeared to effectively prevent deeper tissue injury, typically resulting in only mild skin irritation or transient rash.

4. Discussion

The widespread use of lead–acid batteries in the early 20th century caused substantial occupational lead exposure and serious adverse health effects among workers [11]. Unregulated environmental lead exposure, including leaded gasoline and paint, has been linked to increased risks of cardiovascular disease and idiopathic intellectual disability in the general population [12]. A century later, the rapid expansion of electric vehicles has driven the widespread adoption of secondary batteries; however, the occupational health hazards associated with their production remain poorly characterized.

The secondary battery industry comprises multiple sub-sectors, including lithium production, cathode and anode material manufacturing, separator and additive production, and battery recycling, each of which involves exposure to a wide range of hazardous substances [1,5]. This study focuses on skin disorders, particularly chemical burns, associated with processes such as lithium production and battery recycling within the secondary battery industry.

As a qualitative study, this investigation did not provide quantitative data, such as the prevalence of chemical burns. However, health interviews revealed that many workers reported experiencing chemical burns and contact dermatitis, often during the early stages of their employment. Despite improved safety precautions, chemical burns continue to occur, even among experienced workers. For instance, workers handling lithium hydroxide wear chemical protective overalls and gloves, with tape sealing the gap between them to prevent dust intrusion. However, as work time progresses, the tape tends to loosen, increasing the likelihood of lithium hydroxide dust causing skin lesions at the wrist (Fig. 1). These findings underscore the health risks faced by workers and highlight the urgent need for enhanced safety measures and immediate intervention.

Immediate and appropriate decontamination is critical in the management of chemical burns caused by agents such as sulfuric acid or lithium hydroxide, as it minimizes tissue damage. Prompt irrigation with copious amounts of water is the most effective initial intervention, with a minimum of 15 minutes recommended [10]. In cases of hydrofluoric acid exposure, topical application of 2.5% calcium gluconate gel to the affected area is advised [7]. For hydrophobic substances, including certain organic solvents, washing with soap in addition to water is recommended to enhance removal. For allergic contact dermatitis caused by substances such as nickel or cobalt, dermatological consultation is recommended, and symptoms are often managed through exposure reduction; however, severe cases may require job reassignment or additional medical intervention. In the event of ocular exposure to strong acids or alkalis, immediate irrigation with water for at least 15 minutes is essential, followed by ophthalmologic evaluation if symptoms persist or corneal injury is suspected [13].

The prevention of chemical burns requires a multifaceted approach, beginning with effective ventilation. Adequate local exhaust and general ventilation systems reduce worker exposure to hazardous fumes, mists, and dusts. Emergency response facilities, including safety showers and eyewash stations, should be properly maintained and readily accessible. Appropriate personal protective equipment (PPE)—such as dust masks, safety goggles, chemical-resistant clothing, and gloves—must be used by workers handling chemicals or working in high-exposure areas [10]. Tasks involving significant dust exposure, including lithium hydroxide, require full-body chemical protective suits and air-supplied full-face respirators. Proper fit of PPE, particularly gloves and protective sleeves, is essential to prevent dermal exposure. Regular environmental cleaning, effective dust control, and the use of air showers and clothing changes before exiting work areas are also critical, as secondary exposure may occur during removal of protective equipment, particularly in locker rooms.

The management of chemical burn risks requires the integration of both preventive and responsive strategies [7,8]. Education and training are essential, particularly in this emerging industry, and should be provided to all workers, including new, contract, and temporary employees, as well as those in maintenance, utility, and laboratory roles. Training should address chemical hazards, proper use of PPE, and emergency procedures, including decontamination and evacuation. In addition, a systematic reporting system for chemical burn incidents, including minor injuries, should be implemented to assess the effectiveness of preventive measures and identify recurrent issues. Information obtained from incident reports, surveys, and medical interviews during routine health examinations can help identify high-risk departments and support continuous improvement. Measures to reduce secondary (take-home) exposure—whereby contaminants acquired in the workplace are transported to the home environment—such as changing contaminated clothing before leaving the workplace and maintaining proper hand hygiene, are also important. Finally, clear labeling of chemical pipelines and equipment, together with effective communication of safety protocols, is essential to minimize the risk of accidental exposure.

This study is significant in that it investigated skin disorders among workers in a newly emerging industry, identifying potential causes and suggesting preventive measures. However, the study has some limitations. First, since it primarily focused on skin disorders, a comprehensive assessment of other possible health effects was not conducted. Second, as a cross-sectional study conducted over a limited period, this study could not assess temporal changes or the impact of structural factors such as employment patterns. For example, the packaging process is one of the tasks with the highest potential exposure to lithium hydroxide; however, no cases of skin lesions were reported. This may be because the packaging process is primarily carried out by subcontracted workers, who are frequently replaced, potentially leading to an underestimation of the actual health risks associated with this process. Third, we reported the proportion of workers experiencing chemical burns or contact dermatitis by combining currently observable skin lesions with past experiences of such conditions. Since the workplaces only began full-scale operations in 2023, the duration of employment at the time of the interviews was relatively short. In addition, skin lesions from chemical burns often persist for several months, making it difficult to differentiate between current and past lesions. For this reason, our assessment included both current lesions and prior experiences. Nevertheless, this approach has inherent limitations, as it does not allow for a precise assessment of the occurrence of chemical burns or contact dermatitis over time.

The secondary battery industry is a key component of the electric vehicle sector, driving efforts in many countries to expand and strengthen production capacity. Our findings on chemical burns and contact dermatitis among workers in this industry provide insights that may help prevent occupational skin injuries, ultimately contributing to the safety and well-being of secondary battery workers worldwide.

CRediT authorship contribution statement

Dong-Hee Koh: Writing – review & editing, Writing – original draft, Methodology, Investigation, Formal analysis, Data curation. Yong Lim Won: Writing – review & editing, Validation, Supervision, Project administration, Methodology, Investigation, Funding acquisition, Data curation, Conceptualization. Hwa Yeon Lee: Writing – review & editing, Investigation, Data curation, Conceptualization. Sang-Gil Lee: Writing – review & editing, Investigation.

Patient consent form

All workers agreed to participate in the medical interview and submitted signed consent forms.

Ethics statement

The study protocol was approved by the Institutional Review Board of the Occupational Safety Health Research Institution, the Republic of Korea Occupational Safety and Health Agency (OSHRI-202402-HRBR-001).

Data availability

The original data supporting this article cannot be disclosed publicly in accordance with the policy of the pertinent governmental authority.

Statement on the Use of AI Tools

During the preparation of this manuscript, generative AI tools were used to assist in language editing and improving the clarity of expression. The authors take full responsibility for the content and confirm that all intellectual input and conclusions are their own. No AI tools were used to generate data, perform analysis, or draw scientific conclusions.

Funding

This study was supported by a grant from the Occupational Safety and Health Research Institute (OSHRI) (2023-OSHRI-738, 2024-OSHRI-538), funded by the Korea Occupational Safety and Health Agency (KOSHA).

Conflicts of interest

The authors declare that they have no conflicts of interest.