Does household appliance wires such as toasters washing machines etc. contain lead.

With all the wire I have scraped, I really don't believe it does it is either copper or aluminum.
Old plumbing is more likely to contain lead. Also if you are worried about lead poisoning, from what I have heard you have to have direct contact with it such as kids eating paint chips or drinking water from old pipes containing lead.

If there is lead it would be in the plastic insulation around the wires. More common in the kind of flexible plastic coating that an extension cord has. Wash hands before eating, launder work clothing separately... actually those chemicals in your deck are more likely to cause you trouble.

One possible source would be soldered connections. I have no idea whether lead or not.
Just mentioned as a possibility.

Yeah the soldering is probably the worst as far as lead goes.

There has been an initiative lately called ROHS by the EU called Reduction in Hazardous Substances which has resulted in elements such as lead, cadmium and mercury to be reduced significantly. Solder was composed of lead and tin. The lead has mostly been removed from consumer items at the expense of reliability. Solder until recently contained a large proportion of lead. Lead was removed from plumbing solder a long time ago.

Wires used for power transmission are either copper or tin plated copper.

The heating elements for toasters and dryers might be composed of resistance wire which may be a mixture of Nickel and Chromium.

Inside integrated circuits there may be very fine Gold wires.

Silver plated wires might exist in the Microwave because silver is highly conductive and at high frequencies current is conducted only on the surface of the wire.

Aluminum is used sometimes for power transmission like service entrance cable to your house and sometimes to get power to high current appliances.