I don't and haven't done so for many years. I had read, from several sources, about what was in it and decided to stop using it. Instead I turned to true white vinegar, rather than the chip shop stuff. I used to be able to buy 5 litre containers locally but now have to buy online. It doesn't leave a smell, softens fabric quite well, helps keep the machine clean, can be used for other cleaning jobs - what's not to like?
Rhonda had this link on her blog so will also link to it here.
I have also recently ordered 1 kg food grade each of citric acid and bicarbonate of soda, for cleaning and baking purposes. Since putting bicarb and vinegar down my sinks once a week, smells that were building up have gone.
I use citric acid to clean my kettle and help get limescale from taps and remove the grunge from the base of them where they join the sink. I also use it whilst making elderflower cordial. If you use citric acid for any other reasons, can you let me know!