B. A Test that Targets the Various Sources of Lead Exposure in Children

Narrator: This is Science Today. A new technique that detects the chemical "fingerprints" of different sources of lead exposure may help researchers zero in on the causes of childhood lead poisoning, which is typically hard to do. Donald Smith, a professor of environmental toxicology at the University of California, Santa Cruz, tested the technique and says even though the United States has greatly reduced the major sources of lead, a large number of children still suffer from lead poisoning.

Smith : Because we've used lead for so long in a number of different industrial materials, including as an additive in gasoline. As a result of all those industrial activities and the use of lead as combustion in cars, there's enormous amounts of lead, essentially stockpiled in the dust and soil of urban areas.

Narrator: Another major source of lead exposure in children is lead-based paints in old, deteriorating housing.

Smith: The most prudent thing that parents can do to help reduce that potential exposure is just to be aware of how the children may be exposed and how they can, by keeping their environment clean - whether it be the household or the outside environment - how they can actually reduce the intake of lead to the child.

Narrator: For Science Today, I'm Larissa Branin.

C. New Research Questions the Effectiveness of Living Wills

Narrator: This is Science Today. Living wills are meant to ensure that patients can pass on their end-of-life wishes to loved ones, or surrogates, in the event they are unable to make those decisions themselves. But Peter Ditto, an associate professor of psychology and social behavior at the University of California, Irvine, has found that living wills - also known as advance directives - are not doing the job.

Ditto: The surrogates weren't able to predict patient's wishes any better with an advance directive than without one. And moreover, that even when they had discussions, the surrogates still couldn't predict the patient's wishes any better than they could without a directive.

Narrator: The big question is why surrogates can't predict patients' wishes better.

Ditto: One of the things that we found is sort of a projection bias. That surrogate's predictions typically look more like their own wishes for themselves than they do look like the patient's wishes.

Narrator: Ditto says the point his research makes is to not assume that simply filling out a living will document will accurately communicate one's wishes. Instead, Ditto recommends longer-term discussions. For Science Today, I'm Larissa Branin.

D. A New, Nationwide Breast Cancer Trial is Underway

Narrator: This is Science Today. A drug therapy that blocks the formation of new blood vessels will be tested nationwide in a new breast cancer trial. Dr. Laura Esserman, Director of the University of California, San Francisco Breast Cancer Center - which is one of the sites participating in this study - says the process of new blood vessel growth is known as angiogenesis.

Esserman: Tumors can't get big if they don't have food and food comes from the blood. And there's specific ways in which tumors recruit the growth of blood vessels to help support them - it's like they're building roads to themselves so they can get supplies in. So the idea is, if you can block the road or destroy the roads or the bridges, that you can stop tumors from growing.

Narrator: The ultimate goal of the study is to determine whether an anti-angiogenic agent can effectively starve tumors in women with earlier stages of breast cancer.

Esserman: We ought to be able to see that and quantify it so that we could have that as a target - say, instead of waiting to see whether people die or don't die, that we can say, well we can see it has an impact on the tumor.

Narrator: For Science Today, I'm Larissa Branin.

E. A National Study Finds C-section Deliveries on the Rise

Narrator: This is Science Today. The National Center for Health Statistics recently announced that Caesarean deliveries are widespread among women of all ages. In a previous study conducted by researchers at the University of California, Davis, it was found that C-section rates doubled in first-time mothers who were over the age of forty. Dr. William Gilbert, chief of obstetrics and gynecology, led that study.

Gilbert: When I couldn't figure out why the caesarean rate was so high, one of my colleagues said, "well, Bill, if you have a 20-year-old woman, she can run faster, jump higher than a forty-year-old woman. Why would you think her uterus would be any different?" Looking at it that way, even though the uterus hasn't been used as in childbearing, it still undergoes the same aging process as the muscles, the bones, the fat tissue and other parts of our body and therefore, looking at it that way, maybe the aging process has more to do with it than we think.

Narrator: Although the National Center for Health Statistics' study was based on women of all ages, the upward trend of older first-time mothers does factor in, as the rates of women giving birth over the age of forty is on the rise. For Science Today, I'm Larissa Branin.