I use mine to run the wort chiller!
However to the serious nature of the post, It appears that the health concerns are as follows:
1. Brand new hoses that have not had enough water running though them to leach out whatever chemicals are in there.
2. As in many things its not incidental contact, or a sip of water or occasional ingestion in small amounts that are the problem, it is questionable hoses that have long term ingestion/contact situations happening.
3. This would mean since much of this is heavy metal contact that is not boiled out of your brew that actually brewing with your garden hose could be something of a crapshoot. Could a few brews hurt you, not likely but long term the damage could be there.
4. You could get your water tested like many do from their tap to see the water profile if you want to use a hose and have a clear mind.
5. You could get a food safe hose and not worry about it. (This may be cheaper than sending your hose water off to a lab to check it.)
6. See what chemicals are found commonly in hoses particular to country of origin. Remember though heavy metals are very slow to be removed if at all from the body so the accumulation factor is what gets anyone.
7. Save empty gallon water/milk/juice jugs ahead of time and fill them with the desired water from the faucet to have available on brew day.
8 Relax, have a home brew or brew period after a riveting discussion I never thought I would have about garden hoses.