ILS
Its not clear whether Airport Security staff are to be subject to testing........ I think BAA are not so keen on implementing random testing, its not clear why they have backed away from it.
However, it is reasonable for all Airside staff to be subject to random testing and perhaps an annual hair test (which can detect drugs taken over the previous 3 months). This is because Airside staff are more representative of the general population (large percentages of whom DO take drugs) rather than safety personnel who are (probably) less likely to take drugs.
Airside staff who take drugs are an easy target for criminals, terrorists and are more likely to engage in other illicit activities (perhaps to feed their habit).
Again, it will be interesting to see how this all unfolds.........