The paint on this piggy bank tested for lead at 7253 parts per million (ppm); that is 11 times higher than the legal limit for lead paint.

Editor's Note: This week we have the first of two special reports on lead.

As a parent, there is a lot to worry about when it comes to the safety of my kids. Lead wasn't high on my list. Lead poisoning in children has dropped significantly in recent decades since the ban on lead-based paint in homes and the phase-out of leaded gasoline. Then came the record toy recalls of 2007, where millions of imported items coated in lead paint and made by household names like Mattel and Fisher Price violated the 30-year-old lead law.

Suddenly, parents, including me, eyed the toys in our homes and on store shelves with suspicion. Extensive research links lead exposure in children to lower IQ scores, neurological and behavioral problems, even anemia.

The toy recalls prompted congress to pass the Consumer Product Safety Improvement Act of 2008.

The Act not only lowers limits for lead and bans certain kinds of phthalates–it makes manufacturers and distributors accountable for products sold to American consumers by requiring items to be certified by third-party labs. But the testing, or certification piece of the Act, was postponed for a year. That raised a lot of questions for me as a reporter and as a parent.

I contacted the Center for Environmental Health, which researches lead, and other toxics, in consumer items and has sued manufacturers and distributors for violating standards.

CEH and KQED were interested in looking at what's sold at discount chains and 99 cent stores because of the history of previous recalls. CEH, through its regular spot testing, also thought that many of the larger retail outlets seem to have improved their process to weed out lead in children's items after the 2007 recalls.

I got some tips from CEH about potentially problematic products to look for. We purchased about 200 items and then CEH did the first round of testing using an X-ray fluorescence (XRF) device. The XRF is a handy tool used by a lot of commercial lead inspectors. It shoots high-energy x-rays at the item and sends back a chemical analysis, including the lead content.

Most items that exceeded the lead limits (600 parts per million) set by the Consumer Product Safety Improvement Act using the XRF device were then sent to a federally-accredited lab, MACS in Hayward, for detailed testing. At the lab, the parts or components that exceeded the lead limits were cut or scraped off and dissolved in an acid solution. Then tests were run to determine the lead content.

View a slide show of several of the items that violate the new lead limits below. We've also put together a list of items that violate the new lead limits, along with the test results.

So how can parents keep leaded toys away from kids? In addition to avoiding vinyl products, stay away from metal jewelry.

If you can, choose natural wood toys instead of painted items, especially if they are in yellow. Check the recall list posted by the Consumer Product Safety Commission. Many companies sell home lead test kits for consumer products. They're not 100-percent reliable and can give false negatives-and false positives too. If you're really concerned about your child's lead level, the best thing to do is to get a blood lead test.

Listen to the Playing with Lead – Part 1 radio report online.

(left) A cell imaged with an optical microscope. (right) The same cell imaged by allowing the cell to absorb UCNPs and then irradiating it with infrared light. Each nanocrystal is one thousand times smaller than the width of a human hair. Image courtesy of PNAS.

Thus proceeds Michael Crichton's 2002 thriller, Prey, as the protagonists face off against a malicious swarm of flesh-hungry nano-robots that are the offspring of a most unholy marriage of biological, computer science, and engineering research efforts.

Real science capabilities lag somewhat behind, but researchers succeeded recently in demonstrating an exciting new class of nanoparticle with potential applications in biological imaging. The new crystals, more formally known as lanthanide-doped upconverting nanoparticles (UCNPs), were fabricated and studied under the direction of principle investigators Bruce Cohen and James Schuck at Lawrence Berkeley National Laboratory's Molecular Foundry, and results were published on June 18^th in a paper by Shiwei Wu and others in the Proceedings of the National Academy of Sciences (PNAS).

Happily, while Crichton's nanoparticles coordinated an attack on a your vital organs, these particles behave more like benign light bulbs. After allowing a living cell to absorb the UCNPs, researchers shine infrared laser light on the cell, and the nanocrystals within light up like a Christmas tree in red or green arrays of dots. These, in turn, can easily be spotted using an optical microscope and used to map out particle distributions within a cell, yielding information impossible to obtain by other methods.

The method, known as single-molecule imaging, has been demonstrated using other nanoparticle types, but UCNPs are unique because of their uncommon brightness and stability, and because they are powered by infrared light. This is both good for the studied cells, because infrared light is less damaging than visible or X-ray frequencies, and good for the people measuring them, because it can probe more deeply into tissue than other types of light. In fact, one prospect for future research is the imaging of entire animals.

Reflecting on the research effort's long-term goals, Cohen commented that cross-disciplinary sharing of ideas is crucial. "In general, we'd like to bring nanoscience to the larger scientific community, especially biology, where few researchers have had much exposure to it," he said. "Our goal is to make interesting and useful new materials that will let them do all sorts of experiments that would otherwise be impossible."

Star or Comet?

Remember the solar wind I wrote about a few weeks ago? This stream of protons does more than create comet tails and aurora, it also destroys all of those fancy electronics we work so hard to put into orbit.

The protons streaming from the sun carry a lot of energy, and they leave a lot of this energy behind as they pass through satellites and astronauts that don’t have the Earth’s atmosphere to protect them. The energy released wrecks havoc on the system, throwing electrons and atoms around like a game of ping-pong. This is one form of radiation damage.

Definitely a comet!
This radiation damage is harmless over short periods of time, much like an occasional X-ray at the dentist. However the solar wind becomes a problem for something like the Hubble Space Telescope or our proposed satellite SNAP which are exposed for many years.

To understand how a telescope degrades from exposure to radiation, let me give an extremely quick explanation of how we gather astronomical images. A telescope is very similar to a camera you buy in the store. The large mirror is equivalent to the lens on your camera. The part that suffers the most radiation damage is the Charge Coupled Device, also known as a CCD.

The CCD is essentially the same as the 8-megapixel chip in your digital camera. This serves as an electronic version of film, recording the image through the photoelectric effect rather than through a chemical reaction. If you can still remember how photography was in the days of film, I'm sure you can appreciate the relief of going digital. Astronomers realized this early on and were pioneers in the use of CCDs.

The photons from the subject of the photograph collide with electrons in the silicon of a CCD, knocking them free from their parent atom. The free electrons are then collected in a well near the site of the collision. Once the exposure is complete, charge is moved one well (or pixel) at a time toward a transistor which then reports the number of electrons found. This process is usually described through the analogy of a bucket brigade passing buckets of water from a reservoir to a fire.

When the CCD is brand new, the bucket brigade performs almost perfectly. If I want to observe a star, the image comes out crystal clear. However, after enough time in space and in the solar wind, the CCD begins to show its wear. The bucket brigade gets sloppy at work and has to contend with an increasingly difficult obstacle course, spilling a little bit of water (or electrons) during each transfer. That same star now leaves a trail of charge behind and begins to look more like a comet.

Now, if I am observing a star, I want my image to look like a star, not like a comet. Is that really too much to ask? Unfortunately, the CCD will inevitably deteriorate in space and astronomers have to find ways to predict and correct for this deterioration. This is what we spent yesterday discussing. We passed around some pretty good ideas but still have a bit of work to do before we can prove a new method for correcting the images. I just hope we it figured out before our satellite launches in 2015!

Kyle S. Dawson is engaged in post-doctorate studies of distant supernovae and development of a proposed space-based telescope at Lawrence Berkeley National Laboratory.

latitude: 37.8768, longitude: -122.251