Which type of consumer product was associated with dangerous levels of radiation?

Shoe-fitting fluoroscopes were associated with dangerous levels of radiation because they utilized X-ray technology to fit shoes accurately. These devices, which became popular in the mid-20th century, allowed customers to see their bones and feet inside the shoes through the fluoroscope, providing a visual fit assessment. However, this direct exposure to radiation posed significant health risks, particularly when used repeatedly or over extended periods, leading to potential long-term effects like skin burns and an increased risk of cancer. As awareness of radiation safety grew, these products were phased out of use due to the inherent dangers they posed, solidifying their status as an example of a consumer product that was dangerously radioactive.

In contrast, the other options listed, such as water filters, refrigerator magnets, and LED light bulbs, do not have any known associations with hazardous radiation levels in consumer use.