Boy I really don't think about safety much at all - in the context of men vs. women. Accidents can happen to anyone, regardless of sex, so I don't really see any difference in risk between my riding and my husband's. There are 2 places in the Bay Area I can think of where I won't ride alone, but I'd also advise men not to ride those roads alone either. These are very isolated, remote, seemingly haunted type roads and if you had a major mechanical you'd be completely hosed (the Geysers and Mines Rd.).

I guess the only sex difference safety wise I can think of that affects my riding is I'm no longer enthusiastic about riding through the night alone (i.e. on a brevet or double century), whereas I see male friends doing it without really thinking about it. I've ridden through the night alone before, but now I will generally only do it if I have riding companions. But this is pretty extreme, and I don't expect most cyclists to factor in riding at 2 am as an issue.

I will say the majority of people who do the kind of riding I do (brevets and double centuries) are men, and I've had discussions with people about why that is. I do believe that child care is a big factor - it certainly had been for me. Even when we arranged child care, I always had more guilt around leaving the kid for the day to ride than my husband did. Now I've pretty much made a decision not to do any rides over 400k for the next 3 years because during my 600k last year, I really felt bad about being away from home for so long - and the kid is (I hope) going off to college in 3 years, so she's not going to be home forever. I can knock off a ride 400k or less and be home that night (or wee hours of the morning), but 600k, etc., takes both days of the weekend.

I never commuted to work because of (1) inconveniently placed bridges between my work and home with no way around them and (2) lack of shower facilities at work.