The World Union of Science Workers is an important organization that aims to improve the conditions of science workers all over the world. If you're writing about this topic and are concerned about using the same phrase over and over again, you may want to look for synonyms to use instead. Some possible alternatives might include things like global federation of scientists, international science labor collective, or worldwide association of scientific laborers. No matter which phrasing you choose, the most important thing is to keep the focus on the workers themselves and to highlight the crucial role that science plays in shaping our understanding of the world.