The development and manufacturing of nickel-cadmium (Ni-Cd) batteries in the early to mid-20th century introduced significant environmental and health risks, primarily due to the use of cadmium, a highly toxic heavy metal. The industrial processes involved in producing these batteries often led to occupational hazards for workers and environmental contamination near manufacturing sites. At the time, awareness of these risks was limited, and regulatory frameworks were either nonexistent or insufficient to address the dangers posed by cadmium exposure and improper waste disposal.

Cadmium, a byproduct of zinc and lead mining, was widely used in Ni-Cd batteries due to its ability to form stable electrodes with high energy density and long cycle life. However, cadmium exposure, whether through inhalation, ingestion, or skin contact, posed severe health risks. Workers in battery manufacturing plants were particularly vulnerable to cadmium poisoning, which could lead to acute and chronic health effects. Acute exposure often resulted in respiratory distress, kidney damage, and gastrointestinal issues, while chronic exposure was linked to lung cancer, bone disorders, and kidney failure. Studies from the 1950s and 1960s documented elevated cadmium levels in the blood and urine of battery factory workers, with some cases showing symptoms of itai-itai disease, a condition previously observed in cadmium-polluted regions of Japan.

The industrial processes for producing Ni-Cd batteries involved several stages where cadmium exposure was likely. These included the preparation of cadmium oxide or hydroxide powders, electrode fabrication, and cell assembly. Dust control measures were often inadequate, leading to airborne cadmium particles in workplaces. Ventilation systems, where they existed, were not always effective in reducing exposure levels. Personal protective equipment, such as respirators and gloves, was not consistently enforced, leaving workers at risk. In some cases, factory floors and equipment were contaminated with cadmium residues, which could be inadvertently transported outside the workplace on clothing or shoes, further spreading the hazard.

Waste disposal practices in early Ni-Cd battery manufacturing were another major concern. Cadmium-containing waste, including scrap materials, spent electrolytes, and defective batteries, was frequently discarded without proper treatment. Landfills and open dumping were common, allowing cadmium to leach into soil and groundwater. In some instances, industrial wastewater containing cadmium was discharged into rivers or sewers without adequate filtration, leading to contamination of aquatic ecosystems. The long-term persistence of cadmium in the environment meant that even small releases could accumulate over time, posing risks to wildlife and nearby communities.

Public and scientific awareness of cadmium's dangers grew gradually during the mid-20th century. Early reports from occupational health studies highlighted the toxicity of cadmium, but these findings were not immediately translated into widespread industrial reforms. Some manufacturers implemented basic safety measures, such as improved ventilation or worker hygiene protocols, but these were often inconsistent across the industry. The lack of standardized regulations meant that practices varied significantly between companies and regions. In countries with more advanced industrial hygiene standards, such as the United States and parts of Europe, efforts to monitor and reduce cadmium exposure were more pronounced, but even there, enforcement was uneven.

The perception of risks associated with Ni-Cd batteries was also influenced by their widespread adoption in consumer and industrial applications. The batteries were valued for their reliability and rechargeability, particularly in portable electronics, emergency power systems, and aviation. This demand sometimes overshadowed concerns about their environmental and health impacts. While some researchers and advocacy groups raised alarms about cadmium pollution, the general public remained largely unaware of the issue until well into the latter half of the 20th century. Media coverage of cadmium-related health incidents was sporadic, and the battery industry did not face significant pressure to change its practices until much later.

The eventual shift in industry practices was driven by a combination of scientific evidence, regulatory action, and changing public attitudes. However, during the early decades of Ni-Cd battery production, the primary focus was on improving performance and reducing costs rather than addressing environmental or health risks. Some manufacturers experimented with alternative materials or processes to mitigate cadmium exposure, but these efforts were limited in scope. The high cost of cadmium and its toxicity did prompt some research into nickel-metal hydride and other less hazardous battery chemistries, but Ni-Cd batteries remained dominant for many years due to their technical advantages.

In summary, the early manufacturing of nickel-cadmium batteries posed significant environmental and health risks due to cadmium exposure and inadequate waste disposal practices. Occupational hazards for workers were severe, and environmental contamination was a persistent issue. While awareness of these risks grew over time, initial responses were fragmented and insufficient to fully address the dangers. The legacy of early Ni-Cd battery production underscores the importance of considering environmental and health impacts in the development of new technologies, even when their immediate benefits seem compelling.