In my opinion there is only a social problem. In every european country a great number of athletes are immigrated from other countries. But not only from Sub-saharan Africa. You tell about arabian irish sprinter. Are the arabian people famous for their sprinting? A great number of immigrant, at least in Italy, are from east europe. For me the problem are the opportunities in a society. What were in the past the opportunities for Afroamerican people (in USA) in studing or other work, which are not showbusiness, music and some sports (basket, football and athletics)? For me this situation is changing in the usa. Why? In the past the most important long jumper, triple jumper, sprinter (60m, 100m, 200m, 400m) and runner in 110h and 400h were only or mainly from USA. And so, from a long time they were afroamerican. There were european (whites) athletes that were capable to compete with afroamerican athletes. But in USA there weren't white sprinter or jumper... Why? It's cultural. And opportunity.
My father was a long jumper in National Athletics italian team at the beginning of '70. A black long jumper from the USA athletic team (i don't remeber the name but i could find it) ask to my father if his record was over 8.00 m (His record was less than 8 meters) because this athlete saw my father during a competition. In this competition, my father threatened to win. But for a number of judicial errors was given nil to better performance. The athlete was talking about, agreed with my father. He did not believe to be stronger because black, and my father did not believe to be weaker because white.
About the opportunity for an immigrant. In France the majority of sprinter are second or third generation from immigrants from ex-colonies. They are poorer then the majority of French white people. It's normal. So this situation only motivates people that have less opportunities in this society.
In the past we thought that oriental people weren't capable to run fast or jump high etc... Now we have more and more longjumper from China, or Liu Xiang in 110h! Mennea was fast, but was very skinny. What was his greatest skill? Stubbornness and the desire and will to emerge and get results.
It was probably less talented than others. But obtained what he wanted.
And now how much young well-off white people have with this feeling? Very few! How much people with no other opportunities? A lot!
Now the opportunities are for Carribean sprinter and no more the same for Usa afroamerican sprinter. In the future will be different. And this social situation explains well the use and distribution of doping.
If you need to stand out, use it, otherwise leave the sport or practice it as you can.