Citrus toxicity in male rats

[ViciousCurse]

I looked in the reference thread for information and I've done a bit of research, but why is citrus toxic to male rats? I always see that it could cause certain types of cancer, harm their kidneys, kill them, etc. Maybe I've always looked in the wrong spot or used the wrong keywords on Google, but I've never been able to find the reasoning behind why citrus is so toxic to male rats only.
At least according to Isamu Rats's Feeding Fruits and Vegetables page, oranges have D-Limonene, which is a chemical found in peels of citrus plants. In humans, it promotes weight loss, prevents cancer, treats cancer, and to treat bronchitis. It's also used in flavoring of beverages and gum.
I looked up "why is D limonene so toxic to male rats" on Google just now and this was the first result, which is just an outline of how high doses of this citrus chemical can be deadly to male rats. I didn't go too much more in depth of my search, but that was the first result.

I'm pursuing a Biology degree and I'd love to be an animal educator one day, so I really want to know the WHY. If no one knows why, I'd love to hear speculation as well.

*I'm not using this lack of information as an excuse to feed my rats citrus-- my male rats will never get oranges, lemons, etc.
**Also, click the green words to go to the links and the resources I found. My post was becoming a jumbled mess with all the links.

 

[SQ]

Read this on a medical group for rat owners

d-limonene, which has been proven to cause kidney cancer in male rats.

and

Note: On the subject of fruit, there has been some discussion regarding oranges causing cancer in male rats. It is the consuming of very large amounts over a long period of time of d-limonene in orange rind and commercial orange juice that they are referring to. The actual meat of the orange is not a problem and can be given to both female and male rats.

 

[ViciousCurse]

Ooh, thank you SQ! I'm assuming that the seeds are also unsafe.
How sensitive is this D-Limonene "allergy" in male rats? Can they be given citrus meat that was previously touching the peel or?

 

[SQ]

Ooh, thank you SQ! I'm assuming that the seeds are also unsafe.
How sensitive is this D-Limonene "allergy" in male rats? Can they be given citrus meat that was previously touching the peel or?

I would assume that seeds would not be ok, but no idea …… many types of seeds are unsafe such as apple seeds and the avocado pit

sorry, no idea as I have never fed my rats oranges
nor have I read anything about that, but the quote says large amounts over time

 

[ViciousCurse]

It seems a lot of pits and seeds in fruits are unsafe for animals in general, just like cedar bedding is toxic to a lot of different animals (I may be wrong on the type of wood, I just generally avoid any wood shavings or bedding because I can't remember anything for the life of me and don't want to make a terrible screw-up). I haven't tried avocados for my rats, but I would like to one day. I MAY try oranges, but just a small amount once a month simply because I'm paranoid.
And because I love oranges and I might eat them before my rats can get to them.