WARNING: This product (vacuum cleaner) contains chemicals known to cause cancer,
Under IMPORTANT SAFETY INSTRUCTIONS in the owner's manual for a Hoover vacuum cleaner.
WARNING: This product contains chemicals known to the state of California to cause cancer, birth defects or reproductive harm. WASH HANDS AFTER HANDLING.
Wash hands after handling? Seriously? on a vacuum cleaner? 
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= new reply since forum marked as read
The one time I wish it had been Chinese made... 
to carry a particular Warning label. It is a domestic chemical product and I find no argument with California regulations.
I suspect but can’t offer as fact, that such labeling is required more often with foreign made goods. I’ll explain my suspicion.
I suspect your Hoover vacuum cleaner was made in China. Please check the country of origin. Lead is a cheap, versatile and useful substance. In plastic it acts as a stabilizer. Components of the vacuum cleaner are likely made of plastic. Lead is also used in China for manufacturing electric cords so they stay soft and pliable. I noticed the very same Warning label on a made in China blow dryer in a hotel where I recently stayed.
As Ednahilda noted, Christmas lights are a danger as well for the same reason, they likely contain lead. Please DO NOT permit children to handle strings of lights and yes please wash your hands after touching or handling them.
It might be tempting to consider California regulations a bit fussy, but a genuine health hazard remains a health hazard, especially on a cumulative basis. Since that one state requires such labeling, all product sold in the U.S. has that same labeling. Consumers across the country are made aware of a potential risk.
KakistocracyHater mentioned that made in China products often “smell strongly” including a bathroom rug and gloves he or she purchased. Formaldehyde is a carcinogen and is used in China to treat textiles. Textiles spend months in dark containers and months on ships traveling the ocean. Subject to darkness and moisture, textiles would otherwise be fouled by mold and mildew by the time they reached the big box stores.
In the U.S. we have regulations regarding the exposure limits to formaldehyde in the workplace but we have no such regulation for consumer products in the home. Consider your repeated exposure to foreign made textiles and then ask yourself if they should come with a Warning label.
As a business person situated here in the U.S. if I manufacture or sell a product that harms a consumer in some way, I can be sued in any court in the U.S. and be held accountable. The same is not true for foreign companies especially ones located in China. The Chinese government will not permit any foreign judgment to be exercised within their country and so consumers are unable to obtain redress for any harm done to them by companies in China. Manufacturers in China are free to produce goods with impunity. So I would like to see product labeling that notifies consumers of made in China goods, that with purchase of that product, they are assuming the cost of all risk of harm posed by that product.
On the silly side of product Warnings, I recall reading about a personal lubricant jelly that warned consumers not to eat the jelly and instructed them to apply the jelly to the involved body region. My forehead struck my desk as I was dumbfounded over the necessity of such a product Warning. Soon, Freepers came to mind and I could imagine them sitting down with the personal lubricant jelly and toast so I eventually came to understand that Warning label. 
*To anyone familiar with my unrelated lawsuit, I am on the call list and waiting each day on a call to go to trial the following day. (I’m fighting banksters.)
Just be careful. It's fra-gee-lay...
