Q:

Phone travel charger for powering circuits dangers

I am thinking of using a phone travel charger to power a circuit.Ratings:
input:110-240VAC(my outlet has 220volts) 50/60Hz 0,3A
output:DC 5,2volts at 400mA
The problem is that 220 V are of course dangerous and I 'm not sure of how safe is my charger.
My question is:do phone travel chargers have fuses inside them in case there might be a component failure and an electric shock would become possible?
I also opened the case a few times ,but I didn't modify anything inside and before I put it back last time,the circuitry was intact.
EDIT:Here are the requested images-

A:

The problem is that 220 V are of course dangerous and I 'm not sure of how safe is my charger. My question is:do phone travel chargers have fuses inside them in case there might be a component failure and an electric shock would become possible? 

It looks more competent than many, but is a low cost hand built product.
That is not necessarily bad in itself but raises doubt about the things than cannot be checked visually. 
They have isolated high and low voltage moderately well with the gap in the PCB copper area and have added a slot where the low to high voltage feedback optocoupler is to increase "creepage distance". These two aspects show they understand what is needed and have made efforts in the right direction. What cannot be seen is the quality of the switching supply transformer construction and this is crucial. It is possible to "cut corners" badly on such things to save a small amount of money and you cannot tell directly if they have done so. 
BUT there is another area where they HAVE cut corners to save money (or just do not care) and this suggests that you may be unwise to trust them with your life.
There is NO input RFI (EMC) filtering at all on the mains input and the supply would not pass modern certification requirements for this reason alone, let alone others which may be unseen. The diodes at top left here rectify the mains.
In the photos below, I have mirrored thge top PCB left for right so that the layout matches the underside view. The only filtering for switching noise is the resistor at top let and the capacitor at bottom left.  The resistor also serves to limit the inrush current when 1st plugging ioj the power supply. The amount of noise filtering would not be enough to meet regulatory requirements.
The high to low voltage PCB copper gap can be seen and the slot where the opto isolator is. I've seen MUCH worse than this.
If you have used this with your phone for some while and the phone does not die then they MAY have made a good job of the transformer. Any such supply is a gamble but this is potentially better than many. Whether potentially and "actually" match is unknowable.

DanielPSUV3.jpg

