Triclosan, Still

May 21, 2013

I’ve written here a number of times over the past couple of years (most recently here) about triclosan, an anti-bacterial and anti-fungal agent that is used in a wide variety of consumer products, including anti-bacterial soaps, toothpaste, deodorant, mouthwash, other cosmetic products, and household cleaning supplies.   The US Food and Drug Administration [FDA] has been conducting a safety and effectiveness review of triclosan for some time now. The review was originally scheduled to be released in April, 2011; last summer, it was promised by the end of the year (2012).  We’re all still waiting.

The Singularity Hub site has an article on this ongoing saga.  It gives a bit more of the history: the FDA issued draft guidelines in 1978, which classified triclosan as “not generally recognized as safe and effective”.  Since the guidelines were never finalized, nothing changed.

The FDA has not given an updated timetable for the release of its review.

Triclosan Again

May 5, 2013

The Yahoo! News site has an article from the Associated Press [AP] about the US Food and Drug Administration’s [FDA] ongoing review of triclosan, an anti-bacterial and anti-fungal agent that is used in a wide variety of consumer products, including anti-bacterial soaps, toothpaste, deodorant, mouthwash, other cosmetic products, and household cleaning supplies.  The FDA’s original goal was to release the results of this review in April, 2011; clearly they are a bit behind schedule.   (According to the article, the results should be released later this year — or, at least, real soon now.)  Triclosan does have one use explicitly approved by the FDA: it is used in some toothpastes to help prevent gingivitis.  Its other uses have not, as far as I know, been subject to any formal approval process.

I’ve written here a couple of times before about the use of triclosan.  It is suspected, based on animal studies, of being an endocrine disruptor, boosting the effect of testosterone and estrogen, and reducing that of thyroid hormones.  Another animal study, reported last summer, suggests that triclosan can interfere with muscle function.   What is most striking, though, is that, for its main use, as an anti-bacterial agent in consumer products, there is essentially no evidence that it has any value at all.  As the FDA website, and other publications, have said for some time:

For other consumer products, FDA has not received evidence that the triclosan provides an extra benefit to health. At this time, the agency does not have evidence that triclosan in antibacterial soaps and body washes provides any benefit over washing with regular soap and water.

This is not to diminish, in any way, the importance on washing in  general, and washing ones hands in particular.  (The Centers for Disease Control have resources on hand hygiene.)  But, as the FDA’s note suggests, the evidence suggests  that ordinary soap and water work just fine.  As I wrote in an earlier post:

My own conclusion is that, since I have seen no evidence that these anti-bacterial products provide any benefit, and since there may be some risk, they are not worth using, especially since they cost more than plain old soap.

Apart from the possible negative effects of any particular chemical, there is a general argument for not using anti-microbial products indiscriminately.  There is a possibility that excessive usage may contribute to antibiotic resistance, and there is also a risk of disrupting the normal population of microbes that are part of our personal biosystems, which can lead to serious health problems.  It hardly seems worth much risk to use something, like triclosan, that in most cases doesn’t seem to work anyway.

DEET Resistant Mosquitoes

February 25, 2013

Most readers, I’m sure, are aware that mosquitoes are a transmission vector for a number of rather nasty diseases, including malaria, yellow fever, equine encephalitis, and dengue fever.  The standard advice, in regions where mosquitoes are common, is to keep one’s skin covered, to the extent possible, and to use insect repellent liberally.  One of the most common active ingredients in repellents is a chemical usually referred to as DEET (more formally as N,N-Diethyl-meta-toluamide or [IUPAC] N,N-Diethyl-3-methylbenzamide), an oily compound originally developed by the US military after the experience of jungle warfare in World War II.   Various ideas have been suggested to explain why DEET works; today, the consensus seems to be that insects just don’t like the smell.

However, a report at the BBC News site suggests that DEET’s effectiveness can be reduced because mosquitoes can adapt to it.  One type of adaptation is genetic.  There are always some individual insects that are less susceptible to DEET than average, and heavy use of the repellent creates evolutionary selection pressure favoring that lack of sensitivity.  (This is parallel to the evolutionary process leading to the development of antibiotic-resistant bacteria, or of herbicide-resistant weeds.)   This is a process that takes some time to occur, though mosquito generations are of short duration.

Some recent research indicates that there is another, shorter-term form of resistance that occurs.  Researchers at the London School of Hygiene and Tropical Medicine studied the effect of DEET on Aedes aegypti mosquitoes, which carry dengue and yellow fevers.  The mosquitoes were initially given the opportunity to feed from a human arm which had been covered with DEET; the repellent did, in fact, repel them.  However, when the same mosquitoes were presented with the same opportunity a few hours later, the repellent was significantly less effective.

To try to understand what was happening, the researchers measured electrical activity in the insects’ antennae (the location of the olfactory receptors).  Somehow, the first exposure to DEET de-sensitized the mosquitoes, so that their olfactory response was diminished.  According to Dr. James Logan,

We were able to record the response of the receptors on the antenna to DEET, and what we found was the mosquitoes were no longer as sensitive to the chemical, so they weren’t picking it up as well.

There is something about being exposed to the chemical that first time that changes their olfactory system – changes their sense of smell – and their ability to smell DEET, which makes it less effective.

The research paper [PDF available] has been published at the Public Library of Science, in the journal PLoS One.

More work will be needed to determine how long this short-term effect lasts, and whether it occurs in other species of mosquito.   Using repellents containing DEET is still a lot better than using nothing, but understanding these effects may help us develop even more effective protection.

Dr. Watson Goes to Work

February 10, 2013

Back in early 2011, I wrote a number of posts here about IBM’s Watson system, which scored a convincing victory over human champions in the long-running TV game show, Jeopardy!.  The match, as a demonstration of the technology, was undoubtedly impressive, but the longer term aim was to employ Watson’s ability to cope with natural language and to assimilate a huge body of data for work in other areas, such as financial services, marketing, and medical diagnosis.  It’s also been suggested that Watson might be made available as a service “in the cloud”.

On Friday, IBM, together with development partners WellPoint, Inc. and Memorial Sloan-Kettering Cancer Center, announced the availability of Watson-based systems for cancer diagnosis and care.

IBM , WellPoint, Inc.,  and Memorial Sloan-Kettering Cancer Center today unveiled the first commercially developed Watson-based cognitive computing breakthroughs.  These innovations stand alone to help transform the quality and speed of care delivered to patients through individualized, evidence based medicine.

Since the beginning of the development, Watson has absorbed more than 600,000 pieces of medical evidence and 2 million pages of text from 42 medical journals.  It has also had thousands of hours of training from clinicians and technology specialists.  The goal is to provide doctors and other care-givers with a menu of treatment options.

Watson has the power to sift through 1.5 million patient records representing decades of cancer treatment history, such as medical records and patient outcomes, and provide to physicians evidence based treatment options all in a matter of seconds.

Keeping up with the latest developments in medical research and clinical practice is a serious issue in health care; by some estimates, the amount of available information doubles every five years.  A system based on Watson may give doctors a better chance of staying on top of all of that.

Three specific products were announced today:

The new products include the Interactive Care Insights for Oncology, powered by Watson, in collaboration with IBM, Memorial Sloan-Kettering and WellPoint.   The WellPoint Interactive Care Guide and Interactive Care Reviewer, powered by Watson, designed for utilization management in collaboration with WellPoint and IBM.

The Watson system has improved technically since its debut on Jeopardy!.  IBM says that its performance has increased by 240%, and its physical resource requirements reduced by 75%.  It can now be run on a single Power 750 server.

There’s more information on the technology at IBM’s Watson site.

Virus-Infested Hospitals

October 20, 2012

Most readers, I suspect, will have run across news stories or other reports of nasty infections sometimes acquired by hospital patients.  According to a report at Technology Review, there is another worrying category of infection proliferating in hospital environments: computer virus infections of medical equipment.

Computerized hospital equipment is increasingly vulnerable to malware infections, according to participants in a recent government panel. These infections can clog patient-monitoring equipment and other software systems, at times rendering the devices temporarily inoperable.

The advent of the microprocessor and Moore’s Law has meant the introduction of digital technology, often replacing electro-mechanical control systems, in everything from toasters to “fly-by-wire” aircraft.  It should come as no surprise that many medical devices are now controlled by software as well.  This of course means that all the problems of software, including program bugs, security vulnerabilities, and malware, are part of the package.  Also, as with industrial control [SCADA] systems, the undoubted convenience of linking these devices to a network provides a convenient vector for malware infections.  (The direct connection may be to an internal network, but there is often a path to the Internet lurking somewhere in the background.)  In addition, hospital personnel, like workers in other fields, bring in personal laptops, USB memory sticks, and other devices, sometimes with some undesirable extras.

Another difficulty with medical equipment is also reminiscent of the SCADA case.  For obvious reasons, the vendors and users of these devices place a high value on availability — the machine should be ready for use whenever it is needed.  This means that scheduling downtime for, say, installing software patches is not popular.  In addition, some manufacturers do not allow any modifications to their equipment or its software, even to install security fixes.  This stems in part from the requirement that the devices have to be approved by the FDA; rightly or wrongly, some vendors believe that installing such fixes might require the device to be re-certified.

In a typical example, at Beth Israel Deaconess Medical Center in Boston, 664 pieces of medical equipment are running on older Windows operating systems that manufactures will not modify or allow the hospital to change—even to add antivirus software—because of disagreements over whether modifications could run afoul of U.S. Food and Drug Administration regulatory reviews, Fu says.  [Prof. Kevin Fu, associate professor of computer science at the University of Massachusetts, Amherst]

These security issues were the focus of a meeting last week of the Information Security & Privacy Advisory Board at the National Institute of Standards and Technology [NIST].   Prof. Fu was one of the attendees, as was Mark Olson, Chief Information Security Officer at Beth Israel Deaconess Medical Center in Boston MA.

At the meeting, Olson also said similar problems threatened a wide variety of devices, ranging from compounders, which prepare intravenous drugs and intravenous nutrition, to picture-archiving systems associated with diagnostic equipment, including massive $500,000 magnetic resonance imaging devices.

Hospitals have not, historically, had to focus very much on computer security.  With today’s equipment, though, they have become security administrators whether they like it or not.  As with SCADA systems and many others, there is some catching up to do.

Missing Vaccinations

August 27, 2012

Vaccines against infectious diseases are one of the great success stories of modern medicine.  Their widespread use has practically eliminated some terrible diseases, like smallpox and polio, and has greatly reduced the incidence of some former scourges of childhood, such as measles and pertussis (whooping cough).   Vaccination programs work in two ways.  The first, and most obvious way, is the stimulation of immunity to the disease pathogen in the vaccinated individual.  The second is the production, when vaccination rates are high, of what is called “herd immunity”.  By reducing the number of individuals susceptible to infection, this makes it harder for the disease to spread; it also provides protection to those who are unable to be vaccinated, perhaps because of allergies or compromised immune systems.  This is the reason that smallpox vaccination, for example, has historically been required for all children entering school.

Some recent research, reported in an article at Science Daily, highlights some recent trends that might reduce the effectiveness of vaccination in promoting public health.  Some US states allow parents to obtain “personal belief” exemptions from vaccinations that would otherwise be compulsory.  A group of researchers from the University of Pennsylvania School of Nursing studied vaccination data from more than 7,000 public and private schools in California, which allows personal belief exemptions; the data cover ~500,000 kindergarten students.  Just looking at the period from 2008 to 2010, the number of students with one or more exemptions increased by 25%.  Also, some schools and school districts had very high rates of exemption; in one county in northern California, nearly half the students were not vaccinated due to exemptions.

The public health implications of losing vaccination’s benefits should not be underestimated.

Measles once infected four million people and killed 4,000 of them each year, mostly young children. With high measles vaccine coverage over several decades, endemic measles was eliminated in the United States as of 2000. The current routine childhood immunization schedule is estimated to prevent 42,000 deaths and 20 million cases of disease and to save $14 billion in direct medical costs per U.S. birth cohort.

There will always be a few individuals for whom vaccination is not a good idea, for sound medical reasons.  But skipping vaccinations on the basis of junk science and fashion puts everyone at greater risk.

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