Radiation control method

Radiation can be used for sterilization, but microgranisms vary in sensitivty. What is the relationship between radiation dose & survival?

Exponential

Decimal reduction dose (D10)

Amount of radiation (measured in grays) required to kill 90% of microbial load

Sterilization by radiation applications & examples

Objects that are heat sensitive or would be destroyed by heat sterilization. E.g., spices, pharmaceuticals, medical equipment, canned foods, cartilage for tissue grafts

How does electromagnetic radiation (UV) control microbial growth?

UV radiation of 260-280 nm wavelengths can damage DNA by forming thymine dimers. Exploited to control microbial growth on non-living surfaces and in water.

How does ionizing radiation (cobalt-60) control microbial growth?

Protein & DNA damage.

How does ionizing radiation (e.g., cobalt-60) damage DNA?

Double-strand breaks, stray electrons, hydroxide ions, hydride radicals

Why are ionizing radiation (e.g., cobalt-60) better than electromagnetic radiation?

Higher energy (measured in Grays Gy), better penetration

What is ionizing radiation (e.g., cobalt-60) limited to and why?

Large industrial operations in specialized facilities b/c of costs and hazards of equipment

What is ionizing radiation (e.g., cobalt-60) used for?

Medical supplies & drugs, disposable labware, food industry, insect deinfestation, tissue for grafting