This is the Global News Podcast from the BBC World Service.

I'm Jackie Leonard and in the early hours of Wednesday,

the 24th of May, these are our main stories.

The most senior US public health official is used to start warning

that children and teenagers could be at profound risk of harm from social media use.

Washington has promised nearly $250 million in aid for refugees,

fleeing the fighting in Sudan and Brazil's Minister of Racial Equality

wants a full investigation into racism in Spanish football

after the strike of Aniseas Juniors was the target of racist abuse.

Also in this podcast, a watch that belonged to the last Chinese Emperor

has sold it auctioned in Hong Kong for more than $5 million.

The highest result for any wristwatch belonged to an Emperor

and it is the highest result for any watches that fill its Asia at a sold.

What do we really know about the impacts on children and teenagers of social media use?

The US Surgeon General Dr Vivek Murthy has issued a report on social media

and youth mental health in which he warns of the danger of profound risk of harm.

He says tech companies, policymakers and parents must all play a role in safeguarding young people.

Our Washington correspondent, Gary O'Donohue, told us what the report says about the interaction

of social media and young people's development.

Well, I think it's an attempt to sort of pull together the state of current research

that's out there and to be fair to the Surgeon General,

it says that there are a lot more researchers needed.

...