Massive Post ahead--sorry if it's too much
A friend of mine had trouble with her son testing high (about 25), so after learning the hazards from their experience, we have been fairly cautious in our old house (she attributes lowering his count quickly to use of kelp powder, hidden in pbj sandwiches). Dd tested at a 7.7 at about 1yo and 6 months later she was down to a 3, so I don't feel we have a huge problem, but am being especially cautious to keep things clean.
TSP is tri sodium phosphate, I think. You can buy it at a hardware or paint store. It's designed for wiping down walls prior to applying new paint. Using the water with phosphate dishwasher detergent will bind to the lead so you can pull it off surfaces instead of just moving it around. I go around the house with a roll of paper towels, a garbage bag to collect them, and a cup of clean solution to dip only clean towels into for a one-time use, washing the windows, sills, floors where dust has accumulated, etc. It's wasteful, but worth it.
Be very careful about hepa vacuums. According to the lead inspector who worked with my friend, inexpensive store bought vacuums labeled as hepa are NOT good enough, as most all of them have a blow-by feature that allows some of the air sucked in to go through the motor without being filtered properly, which disperses the dust back into the air. You need a true hepa vac that will capture dust down to 0.3 microns to capture lead dust. It really needs to be one of the ones that's certified for allergens. I plan to order a Nilfisk vacuum next week (to the tune of $400 to $600--mega ouch!). You also want a bag or one-time use cartridge so you don't have to handle the dust or end up spreading it around when you dump it. Many state health departments have professional hepa vacs that you can borrow for free, so call and ask to see if you can do a thorough cleanup a few times a year.
Also, I once spoke with the poison control center nurse who was a lead specialist (dd broke a maraca that was filled with a million tiny lead balls instead of seeds/beans
: ). She had the most info of anyone I've ever spoken to, and sent me a huge packet of information which I haven't had time to read yet. One thing she alerted me to is that you should always make sure to tell the lab that you want your child's blood put into a certified 'lead free vial' for testing. I know this sounds obvious, but according to the nurse, lead free vials are not always used, and a normal vial could skew the results by several points.
Other sources of lead I've heard of...can't confirm all but it can't hurt to list them:
-Vinyl mini blinds are a very real hazard due to moving parts which create dust.
-Anything PVC, apparently lead is a stabilizer in many forms of vinyl, and could be in your garden hose, those plastic/metal hoses that hook up to the newer faucets, etc.
-Ceramic bowls, plates, cups
-Cheap crayons, sidewalk chalk
-Soil near major highways or in cities where lead gas fumes settled over time
-Keys and jewelry (mentioned by pp's)
-Christmas lights (again, vinyl plastic covering the wires)
-Some makeup, hair dyes and ethnic food items--can't remember specifics
-Sign up for the CPSC recall email list--lead recalls seem to come up at least once a month, including children's toys http://www.cpsc.gov/cpsclist.asp
-Candles with leaded/metal core wicks
-Imported Canned foods may have lead solder
Another good info source I found:http://www.calpoison.org/public/lead.html
For lead paint chips or residue on the soil, get some mulch and cover bare soil where you can. Grass or planted areas are considered safer because the lead dust works it's way into the soil and is harder to pick up again.
Here's my favorite article on renovating safely:http://www.taunton.com/finehomebuild...ges/h00108.asp
Also, search the MDC forums using 'lead' or 'lead paint', and you'll find a ton of good information in older threads!