Rule #1: Get your children screened for lead poisoning regularly. Not all doctors do this, so you need to take charge if it's not a regular feature of your children's pediatric exams. In some states, lead poisoning testing is mandated for the youngest children; federally, it's required for those in the Medicaid program. But compliance isn't always guaranteed.
If it were us (and it is), we'd spring for the screening at least for the first couple of years -- and after that if the family abode undergoes any renovation. (Oh, and don't relax just because your child tested fine as a 1-year-old. Research in Chicago showed that 21 percent of children tested at age 1 ended up with elevated BLLs during a later screening -- an "expected" result given the greater mobility, oral behaviors, and outdoor play typical of 2- and 3-year-olds.) Get the doctor to explain the results, but if it's above 5 micrograms per deciliter (half of the current "safe" level of 10 micrograms), we would strongly recommend finding and removing the source of lead exposure.
Rule #2: Evaluate the presence of high-risk conditions at home or anyplace where your child spends a substantial amount of time. The most effective way to reduce exposures to hazards is to make sure they don't exist or to eliminate them if they do. So, if your home predates 1978 (even if it's been updated in the interim) and has any peeling paint or other deteriorating surfaces, leaks, or rubbing doors or windows (or, heaven forbid, your child has elevated lead levels), you need to have your home evaluated for the potential and scope of any lead paint hazard.
Do not, do not, do not try and evaluate the situation through home testing. According to the EPA, home test kits are not reliable enough to give accurate readings. You need professional help.
Rule #3: Check the dirt. If your children play in areas where they're exposed to bare soil that is located near high-trafficked roads or older buildings with peeling paint, get the soil tested or keep your children away. Since the EPA does not find home tests to be reliable, we suggest you hire an EPA-certified professional to evaluate your soil if you have concerns.
And if it turns out you do have a problem? Besides making sure that toys and hands that spend time outside are cleaned often, you'll need to cover any bare soil with a thick barrier layer -- of mulch, sod, sand, whatever -- to raise ground levels. And, certainly, reconsider those plans to plant any vegetables or herbs there. Lead-laden soil is not exactly the best base for food that may hit your family's table.