I'm an airplane painter at work, so I know a thing or two about chromic acid conversion (Alodine 1201) having handled several thousand gallons over the years. Just did a big parts batch today, in fact. You are right that Alodine does not present much of an immediate worker safety problem as the acidity is low. But it contains heavy metals (hexavalent chromium) and cyannide so poisoning is an issue if it's mis-handled. Waste product can be economically disposed of by evaporating down to the solid state and getting it hauled as dry waste. Much cheaper that way. It must NEVER be dumped on the ground or poured into ANY drain as it is a serious ground water pollutant. That's one reason why so many airports and military bases are superfund sites; that's exactly what they did for decades.

Also, Alodine is not itself a weather coating the way anodizing is. Neither Parker/Amchem nor Henkel ever advertised it that way. It is far too fragile. It is however the very best coating to use if you intend to paint or powdercoat. Then the tough paint can protect the fragile alodine which is in turn stopping the corrosion. Henkel advertises 14 year durability for the conversion. But all bets are off if it's not properly primed and painted as it is only a few microns thick and scratches off very easily. It is never recommended for unpainted parts that will be handled. It must be painted within 3-5 days or else removed and re-applied before painting, else the paint will not stick at all. Alodine is much finickier and will not 'take' if the slightest bit of contamination is present. It takes some practice to get right, especially on old metal.

Anodizing OTOH is an ideal weather coating, impervious as it is to both environmental attack and highly scratch/abrasion resistant. The actual anodized aluminum molecules are almost as hard as a diamond which accounts for the coating's toughness. Also it is much thicker than Alodine and can be .001" or more, about 10-20 times thicker than Alodine. You can also make it virtually any color you like. Alodine is either gold (1201) or clear (1001). Anodizing has theoretically indefinite life.

The major safety issue with the sulphuric acid dip for anodizing is that the acidity is much higher and presents an immediate danger of acid burns. Proper handling proceedures and safety habits can alleviate the danger. Sulphuric acid is a simple acid without any nasty heavy metals, so carefully diluting/neutralizing can take it to 'gray water' status so it can be at best legally dumped or at worst disposed of very cheaply. No heavy metals to muck up the groundwater. There are numerous web pages to describe the proceedures for this if anyone is interested. If you are contemplating any of this I recommend you familiarize yourself with some of this info first.

Lack of knowledge is how people get into trouble with these products, like attempting straight dilution of acid instead of reverse dilution. Ditto for when you decide to neutralize; you don't just throw baking soda in the bucket and hope for the best

Jimbo