How do doctors weigh the risks and benefits of diagnostic tests? Sometimes it's harder than you might think. 

Take CT scans, which deliver known doses of radiation to patients. Add kids, for whom radiation risks are higher -- in part because of their smaller developing bodies and because there's more time ahead to see effects of radiation. Now consider a CT scan for a child with severe and chronic sinusitis. A kid who has come to a specialist after having tried other diagnostics and treatments for their condition. A CT scan has the potential to reveal definitively -- more than any other test -- what's going on. 

I wrote about the risk data and the benefits in practice of using CT scans in kids for ENT Today.

The doses are small, but they do add up. As one ENT doctor told me: “I don’t think much about one CT scan. But I do think about two CT scans.”

Photo credit: thesmokingsection on Flickr

River dams: good for generating electricity but bad for fish. In the Northeast US, many ocean fish species swim into rivers and upstream into small tributaries to spawn -- and complete their life cycle. Dams are a major barrier to these migratory fish and so people have come up with a variety of ways to help get fish around the dams -- from trapping and trucking to structures called fish ladders and elevators. 

For ScienceNOW, I wrote about a new report that looked at the numbers of fish using fish passages on three major river systems: the Merrimack, the Connecticut, and the Susquehanna.  Although stated targets at these dams call for hundreds of thousands of fish to pass through, the actual numbers were in the hundreds, the tens, and in the case of river herring on the Susquehanna, single digits. 

The report's authors make their case for dam removal, saying that other dams -- farther upstream or on less ecologically important waterways -- could make up the power loss. Further they point to Maine, where such radical action has been taken on the Penobscot River. 
photo credit: Wildcat Dunny on flickr

Household mold is certainly an unsightly nuisance, but how bad is it for your health? I looked into the question for the Washington Post. Experts say allergic responses are most common. Toxic mold, on the other hand, is more myth than truth -- at least in terms of inhaling invisible spores and becoming severely ill.

The issue is relevant to those states that suffered Superstorm Sandy's exceptional storm surge, which resulted in many flooded homes. I share some revealing reports from the CDC after Hurricane Katrina and from the Institute of Medicine about the health effects of damp places. 

That's me, examining a dragonfly with a hand lens.  I wrote about these amazing creatures -- and the curious people who chase them -- for Audubon magazine. 

While birding and butterflying have long been popular, watching and identifying dragonflies and damselflies is becoming more so.  Easy-to-use field guides are now available and states such as New York and New Hampshire have done comprehensive surveys to determine what species live there.  In the process of training its residents how to survey, these science/conservation efforts have also bred a loyal group of hobbyists and citizen scientists. 

One dragonfly devotee is Thomas Cullen, who took these photos while introducing me to the ways and wonders of dragonflies and their pursuers.  After I let go of her wings, this female chalk-fronted corporal perched on my hand for several seconds, giving me another, more relaxed perspective.

More data on triclosan, the chemical that makes soap "antibacterial," from the Los Angeles Times health blog.  A research team from UC Davis found untoward effects of the chemical in mice.  Animal evidence is not usually enough to change regulations on a chemical.  But in this case, writer Eryn Brown reminds us, adding the chemical to soap doesn't improve soap's effectiveness.  Hand washing with regular soap and water is a perfectly good germ-killing method. 

Quick post on some of my recent Los Angeles Times articles:

In November 2011, the FDA withdrew its approval for using the drug Avastin in patients with metastatic breast cancer.  Now, two new studies suggest the drug might be helpful in early stage breast cancer.  I parse that confusing message here.

The FDA reneges on one action to reduce antibiotic use in food animals, then moves forward on another. But the agency asserts that both decisions were made in the interest of preserving antibiotics that are medically important for humans. Here's the story.

Health and Human Services secretary Kathleen Sebelius overruled a decision by FDA commissioner Margaret Hamburg to make the so-called morning after pill available without a prescription.  Both parties cite science as basis for their opposing decisions on Plan B. I dig into that science here.

Common sense improvements proposed for school lunches devolve into food vs food fights. For instance, should 1/8 cup tomato paste be counted as a 1/2 cup serving because it's concentrated?

When there's just one cancer drug left to try and you're stuck on the waiting list -- my Los Angeles Times story on drug shortages.

Northe Olague has lived with ovarian cancer six-plus years, with the help of surgery and multiple chemotherapeutic regimens. Earlier this year, tests indicated that her cancer was growing again. Her doctor recommended Doxil, but by the time she was scheduled for treatment, she learned that the drug was unavailable.

Olague: "I was in disbelief."

Oncologist Michael Link, who leads the largest professional organization of cancer care providers: “It’s unfathomable.”

The drug’s maker, Johnson & Johnson, says the shortage was initially caused by production line problems.  The worldwide supply of the drug is made at a single Ohio plant.  Other chemotherapeutic drugs are also in short supply for various reasons, including supply chain economics and doctors' incentives to prescribe pricey brand-name drugs.