Final answer:
Minimal levels of laser radiation are considered safe. Alpha radiation is less penetrating and relatively safe compared to other types, whereas ultraviolet light and gamma rays have higher potential for biological damage. Low doses of radiation, even if below natural background levels, might still pose long-term health risks.
Step-by-step explanation:
Only minimal levels of laser radiation are not considered to be hazardous to human health. Laser radiation, like all forms of electromagnetic radiation, can pose risks depending on its intensity and frequency. Alpha radiation is a type of radiation that can be stopped by the dead layers of our skin or a few centimeters of air, making it relatively safe if not ingested. On the other hand, higher frequency radiations such as ultraviolet light, which is filtered out by the Earth's ozone layer, gamma rays, and X-rays have the potential to cause cell damage and can lead to health problems like cancer and genetic changes. Exposure to very low doses of radiation, typically much smaller doses (<100 mrem/year) compared to natural background radiation, is more difficult to assess but can still lead to long-term health issues. Consequently, exposure to laser radiation should be limited to levels that are known to be safe, taking into account the absence of harmful levels of electromagnetic radiation.