Baggage X-Ray Scans are not phytosanitary treatments
In a note published in Biocontrol News and Information [31(2), 11N–12N] Dr Peter A. Follett (USDA-ARS, Hawaii, USA) elaborated on the possible harmful effects of X-ray radiation from baggage or parcels inspection systems when live biological material is shipped.
Insect irradiation studies normally involve application of radiation doses within the range that produce a desired response, for example sterility between 50 and 400 Gy. Most studies of insect radio-tolerance have focused on determining doses that prevent adult emergence or sterilize the adult and thereby prevent reproduction. This information is used to develop sterile insect release programs or to develop quarantine treatments to control insects.
To assess occupational risk for humans, the concept of Threshold Limit Value (TLV) is used, which is the level of radiation to which a worker can be exposed day after day for a working lifetime without adverse effects. However, the TLV for insects is not known. From studies on insects irradiated at doses as low as 20 Gy, Dr Follett estimates the TLV for the most sensitive insects at about 1–5 Gy, meaning a dose in this range would have no adverse effects on insect survival and reproduction.
The radiation dose typically received by objects scanned by a cabinet x-ray system is 0.01 mGy, which is about 1/100,000th of the TLV estimated for the most sensitive insect (1 Gy). The level of radiation exposure from a check-in baggage x-ray scanner (CAT scan) is about ten times higher or 0.1 mGy, but still harmless.
In conclusion, baggage x-ray scans expose biological materials to doses far below those that might have any harmful effects, and no phytosanitary effect should be expected from them.