When Michigan mother Jody Erickson-Neely saw her daughter's face covered in orange dye after chewing on the plush end of a Very Hungry Caterpillar teething toy last spring, she suspected something was not right. Soon Ayva, then 7 months old, developed a rash that lasted a month and required treatment with steroids.

Erickson-Neely lodged complaints with the Consumer Product Safety Commission and the toy's maker, but she didn't learn from them what might have caused Ayva's rash. She then took the caterpillar to a public toy-testing event hosted by the Ecology Center in Ann Arbor. Testers told her the caterpillar had high levels of antimony, a toxic element that is used as a fire retardant and can cause headache and dizziness even in small doses.

But Erickson-Neely, 33, still doesn't know whether the antimony or some other chemical caused Ayva's reaction, or whether there might be any lasting health effects.

Erickson-Neely's experience exemplifies the problems consumers face when they suspect a toy may be toxic: Most toys cause no ill effects. A few contain a single toxin, such as lead paint. But most contain many chemicals, and it is hard to pinpoint which — if any — is dangerous.

The 2008 Consumer Product Safety Improvement Act made it illegal to sell children's products with more than 300 parts per million of lead, which can cause neurological damage, including developmental delays. The 2008 law also bans children's products containing certain phthalates, a common component of soft plastics and some cosmetics that has been linked to reproductive defects, early onset of puberty and low sperm count.

On Dec. 2 the Ecology Center, which is endorsed by the advocacy group U.S. PIRG and other consumer groups, released test results for about 700 children's products screened for a variety of chemicals and heavy metals. (The results are at www.healthystuff.org.) Some consumer groups test products with an X-ray gun. But such equipment is unavailable to most parents, and consumer advocates say over-the-counter testing kits are unreliable.

This holiday season, the Ecology Center is hosting a handful of toy-testing events in Michigan. But national consumer advocates said such opportunities are rare, and they urged parents to rely on a handful of online guides and a few basic rules of thumb in searching for gifts:

• Avoid costume jewelry, which tends to have high levels of lead, including baubles or gems made completely of lead.

• Avoid children's fragrances and cosmetics.

• Avoid toys with buttons, protruding eyes or other small removable parts, as these often have higher toxicity risk and are more likely to be swallowed.

• Avoid plastics when possible, especially those with polyvinyl chloride, or PVC. Since PVC is brittle, it is often augmented with phthalates and stabilizing heavy metals including lead.

• Avoid anything with flame retardants, since such compounds are often toxic and are usually unnecessary. ("Why is a crib mattress flame-retardant? Is your 3-year-old going to fall asleep smoking a cigarette?" asks Jeff Gearhart, of the Ecology Center.)

• Browse such Web sites as www.healthy-stuff.org and www.goodguide.com, and use U.S. PIRG's mobile phone application www.toysafety.mobi. Check out specific toys and look for companies that recur in the safe or unsafe categories.

• Monitor www.cpsc.gov for recall information.

• Keep play areas clean, since kids can ingest toxic materials that slough off toys and mix with dust.

• Opt for "natural" gifts made of unpainted wood, cotton, wool or natural latex.