No one would choose to eat polychlorinated biphenyls, or PCBs — yet we unwittingly do. And a new study finds that the cost of their pervasive contamination of our food supply can be elevated blood pressure, a major risk factor for heart disease.

Weather-monitoring stations in the Lower 48 have been logging record daily highs in temperature at twice the pace of record lows. Yet more evidence of climate warming. Many people have pointed to colder than normal winters — or summers — as evidence that global warming is a myth. Climatologists have countered that weather, the meteorological features that we experience at any given hour or day, may show anomalies even as Earth’s overall climate warms. So weather can locally mask the planet’s overall slowly rising fever. Except that any such mask appears to be disappearing throughout most of the United States, according to a new study.

Negotiators representing 181 nations completed their final prep work in Barcelona, Spain, last Friday, on a new climate treaty — one that they hope to build a month from now at a major conference in Copenhagen, Denmark. But at least one scientist worries that what comes out of the Copenhagen deliberations may not have sufficient coordination and strength to meet the challenges that Earth’s climate has begun throwing at us.

Three groups of healthcare professionals sent a letter to President Obama yesterday asking that he instruct his administration to revise federal flu-mask guidance. What these groups want: formal recognition that two studies last month showed conventional surgical masks are about as protective as the fancy — but much more expensive — N95 respirators in limiting H1N1 infection.

A spot of encouraging news emerged yesterday on the medical-isotope front. The House of Representatives voted 440 to 17 in favor of a bill to reestablish domestic production of molybdenum-99. It’s the feedstock for the most heavily used nuclear agent in diagnostic medicine.

Efforts to get the Large Hadron Collider up and running just encountered a temporary snag, according to yesterday's online edition of The Times of London. A crusty chunk of bread “paralysed a high voltage installation that should have been powering the cooling unit.”

Featured blog: Researchers are working to catalog the DNA sequences of just about every vertebrate genus.

Pregnant women are considered at high risk for suffering complications or death from the new H1N1 pandemic swine flu. So they’re near the top of the list for getting vaccinated. A new international study calculates that up to 400 out of every million pregnant women who receive such swine-flu shots will experience a miscarriage within 24 hours. But not BECAUSE of their flu shots.

Earlier this year, Dutch scientists showed that vaccinating mice against seasonal strains of flu rendered the animals unnecessarily vulnerable to dying if they later encountered a pandemic flu strain. Authors of this study now ask whether there are lessons in their data for parents. Such as whether to ignore recommendations that youngsters get seasonal-flu shots during years when pandemic flu is raging. Others suggest this idea, at least as regards people, is bunk.