Sunday, November 30, 2014

The Declining Availability of Fresh Water

The natural fresh water cycle (the cycling of water from oceans to the atmosphere, becoming precipitation in the form of rain and snow) is the source of the fresh water in the Earth's lakes, streams, and underground aquifers. The water cycle is timeless and largely unaffected by man, except for the probable influence of global warming. But the supply of clean fresh water available to humans (where humans choose to locate) is slowly but surely declining.

Many western U.S. cities rely primarily on water derived from the winter snowpack in nearby mountain ranges. The cities are growing and demand for water is up. To make matters worse, the winter snowpack has been declining in recent years. Some of the snowpack's decline may be due to global warming, but it may also be partly due to normal decades-long cyclic fluctuations in the water cycle. Centuries-old glaciers have been receding; some have disappeared entirely. If the current 30-year trend continues, Montana's Glacier National Park in may not have a single glacier by 2030. This does not bode well for Western lakes and streams.

Some human populations rely heavily on ancient underground aquifers for water to irrigate thirsty crops. China, India, and the U.S. plains States all rely heavily on aquifers that are not being replenished at the rates at which they are being used. Wells in some areas are going dry, leading to a loss of agricultural productivity.

Pollution of freshwater is a constant concern. Industries that use a lot of water or that run the risk of polluting rivers and streams, such as mining for coal, copper, and gold, face increasing government regulation or outright opposition from environmental groups. The world's largest gold mining company, Barrick Gold, shut down a major investment in a massive mine in Chile due in part to costs related to the risk of polluting nearby rivers and streams.

These are not problems that are going to go away quickly. Humans will have to adapt. We'll need to reduce water use in our homes, recycle water wherever possible, locate our human populations nearer to abundant supplies of fresh water, develop agricultural crops that require less water, irrigate crops more efficiently, and improve industrial techniques that require water. Some of these actions are already being taken. As they must, if we are to prosper in the long run.

Wednesday, November 26, 2014

The Benefits of Genetically Modified Crops

Opponents of genetically modified (GM) crops are quick to point out the potential risks involved in planting GM crops and in eating foods with GM ingredients. Some of the risks, such as the potential for encouraging the emergence of "superweeds" that are resistant to the herbicides used on GM crops, and the inadvertent cross-pollination of normal crops by GM crops in nearby fields, are real. Others, such as the potential for causing future unspecified human health problems, are as yet undocumented.

Are there any known benefits of GM crops, other than for the farmer? A recent meta-analysis published in PLOS one concludes that indeed there are. The authors of the analysis reviewed all of the previous reports of the economic and agricultural impacts of three GM crops (soybeans, maize, and cotton) published in English between 1995 and early 2014; 147 studies in all. They found that in addition to improving farmer's profits by 68%, the use of GM crops increased crop yields by 22% and decreased chemical pesticide use by 37%.

Increased profits for farmers is not a bad thing, for it means they pay more taxes and have more money to spend (stimulating the economy). Increased crop yields allows more people to be fed per acre of agricultural land; something to think about as Earth's human population continues to rise even as the amount of arable land remains constant. Finally, reducing chemical pesticide use by more than a third can only be good for the environment.

I'm not saying that GM crops are perfect. I'm well aware that there are risks, some of which may still be unknown. I'm just saying that in any dialogue about whether we should allow GM crops, we should consider both the risks and the benefits, and not just focus on one or the other. Do not be fooled into thinking that there is only one side (yours?) in this debate.

Saturday, November 8, 2014

Increasing Incidence of Colorectal Cancers in Young People

A review of the nearly 400,000 reported cases of cancers of the colon and rectum between 1975 and 2010 reveals some interesting trends. Overall, the incidence of colorectal cancers declined by just under 1% per year, due to a steady decline in persons 50 years of age or older. However, the incidence of colorectal cancers rose in the youngest age group; persons aged 20-34. Based on current trends, rates of colorectal cancers in this age group will nearly double by 2030.

The current study provides no information regarding the cause of the upward trend. But this is how science works; based on an observation, (a rising rate of colorectal cancers in young people) a hypothesis must be formed and further study undertaken to test it.

Perhaps by 2030 we'll know why colorectal cancers are increasing in young people, and also know what to do about it. The optimist in me hopes so.

Thursday, November 6, 2014

The FDA approves a Vaccine for a Rare Meningitis

Last fall an outbreak of a rare form of meningitis called serotype B occurred on the campus of Princeton University. Months later a similar outbreak occurred at the University of California Santa Barbara (UCSB). Although a vaccine against serotype B meningitis was available in Canada and Europe, it had not yet been approved in the U.S. Nevertheless, because of the dangerous nature of meningitis and the ease with which the disease might spread on college campuses (it's spread by close contact such as kissing or sharing eating utensils) the FDA granted emergency approval of the vaccine, just for students of Princeton and UCSB. The vaccine worked, the outbreaks subsided, and a greater crisis was averted.

Recognizing that the normal approval process for a vaccine or drug can take years, the FDA has developed a fast-track approval process for vaccines and drugs that meet certain criteria. Two competing vaccines against meningitis serotype B were fast-tracked under this program, and last week the FDA approved the first one, Pfizer's Trumenba.

And that's interesting, because the vaccine approved on an emergency basis for the students of Princeton and UCSB was the other vaccine, called Bexero, made by Novartis. We hope it's just that Pfizer just did a better (and faster) job of satisfying the FDA of its product's safety and effectiveness.

Now that a vaccine for meningitis serotype B is available, should it become part of the standard vaccination schedule for all children? That hasn't been decided yet, but the decision rests with the Centers for Disease Control and Prevention (CDC), not the FDA.

Saturday, November 1, 2014

New Uses for Wearable Skin Patches

Previously I talked about how wearable skin patches not much bigger than a Band-Aid that could be used to deliver drugs or vaccines (see "A Skin Patch to Deliver the Flu Vaccine"). Wearable skin patches are being developed for other uses as well, including monitoring a patient's vital signs and diagnosing specific diseases.

Swedish researchers are developing a wearable skin patch called the Bio-patch, with embedded wireless micro-sensors and a small battery. The Bio-patch could be used to monitor a patient's vital signs and send them wirelessly to a smartphone or to the patient's doctor. The Bio-patch would permit 24-hour monitoring of a patient, enabling a physician to know exactly when a patient's condition has changed. Sensors have been developed to monitor body temperature and the electrical activity of the heart (an electrocardiogram; ECG) and brain (an electroencephalogram; EEG).

An Australian group is developing a wearable skin patch with tiny micro-needles that penetrate the outer layer of the skin and sample the intradermal fluid. The tiny micro-needles are coated with antibodies that detect the presence of antigens from the malaria parasite, Plasmodium falciparum. The device can detect malaria in a patient without the need for a blood sample and blood analysis. So far the device has only been tested on mice, and only to detect malaria. But in theory, it should also work in humans and it could conceivably be used to test for nearly any disease in which disease antibodies are present in interstitial fluid.

It's a pretty good bet that within the next decate you'll see some of these products come to market.