You will find links to national science writing organisations in the pages of the World Federation of Science Journalists. Look on the left hand menu and you will see a link to Member Associations. Science writing associations often welcome broadcasters and other media professionals as well. Many of the associations that have the word 'writer' in the title, such as the Association of British Science Writers, were often formed in the 1940s when broadcasting was a relatively new medium. Associations that were formed later, such as the European Union of Science Journalists' Associations, often use the word 'journalist' instead.