yes.
And that has been investigated.
I don't know what it's like in Austalia. Hopefully it's better. But here in America you could make a good argument for not eating meat without even considering the animal's welfare. What is happening to the workers is inhumane too,
The book and the movie, Fast Food Nation, goes into it in some detail.
NIH and the AMA have published papers on it.
There is also evidence that people working in the "meat industry" are more likely to commit violent crimes.
Also concerning is how poorly those workers are treated by their company.
these workers are something like 3x more likely to be seriously hurt at work.
Again NIH, the AMA and OSHA have published papers on this.
In the US, many of these workers are migrants (often undocumented) and the companies believe they do not have to consider their rights. I remember reading about a facility that basically kidnapped their workers and made them into virtual slaves.