Answer to Question #309 Submitted to "Ask the Experts"

Q

I work in a research facility and work with ³²P labelled dATP or ³²P dCTP (250 micro curies per week) and have just learned that I am pregnant. Our laboratory has a good exposure monitoring system (badges and finger monitors). However, I would like to know if the exposure levels when pregnant should be lower and if working with dATP/dCTP is an extra hazard with the risk of incorporation into the DNA of rapidly dividing cells in the fetus? Thank you.

A

By taking appropriate protective measures while working with the ³²P-labeled DNA components, the possibility of you or your baby receiving any radiation exposure can be minimal. While ³²P can be a substantial skin exposure hazard due to its high-energy beta emission, it is currently supplied from most manufacturers in containers that include inherent shielding such as Plexiglas. You should also have shielded containers to use when working with it. Research Products International Corporation, for one, can supply a variety of useful containers for virtually any type of laboratory experiment with ³²P. That should prevent external exposure to you.

In addition, your unborn baby is protected from the external beta radiation by you; your abdominal tissue is more than sufficient to shield the baby. Protection from the labeled DNA precursors is accomplished with judicious contamination control measures. To that end, your protective laboratory clothing and use of disposable gloves, as well as carefully performing your manipulation of the ³²P-labeling procedures, employing disposable absorbent surface coverings, and routinely monitoring your work areas and hands by use of a Geiger counter with an end-window or pancake probe or, alternatively, swipes counted by a liquid scintillation counter set for measurement of ³²P, should ensure a contamination-free work environment.

You have a right under the regulations of the US Nuclear Regulatory Commission to declare your pregnancy to your employer. In doing so, the radiation safety program of your company may provide additional monitoring of you or suggest additional precautionary procedures. For example, collecting and counting a urine specimen periodically will provide assurances that no internal contamination has occurred. This is something you can do electively as well. This can be done by aliquoting 1 ml of urine into 10 ml of liquid scintillation counting solution and counting in the ³²P channel. Be sure to establish a background value first.

Bob Zoon, Radiation Safety Officer
NIH