Week of 10/24/10

Dear EarthTalk: What are the environmental benefits of the hydroponic growing of lettuce and other crops?

—Bruce Keeler, Oakland, CA

While organic agriculture is all the rage, growing by leaps and bounds to meet increased consumer demand for healthier food, another option that’s less well known but just as healthy is hydroponics, whereby plants are grown in nutrient-fortified water-based solutions without a soil substrate whatsoever. Besides not needing chemical fertilizers or pesticides (most of which are toxic as well as derived from petroleum), hydroponics also take up much less space than traditional agriculture, meaning that even an apartment window can yield impressive amounts of food throughout the calendar year.

In traditional forms of agriculture, soil facilitates the process of providing the mineral nutrients that plants need to grow. Organisms in the soil break down the nutrients into inorganic basic forms that the plants can then take up accordingly and put to use photosynthesizing. Of course, some of the organisms the soil attracts are unwelcome, and not every speck of soil is ideal as a growth medium, so we have come up with ways to kill off unwanted pests (pesticides) and pump up the ground’s productivity (fertilizers).

But growing fruits and vegetables hydroponically obviates the need for fertilizers and pesticides—let alone soil—altogether. "Without soil, there is little to no microbial activity, so the plants depend on direct nutrients from nutrient solutions," reports Alexandra Gross in E — The Environmental Magazine. "And because hydroponics occur in a highly controlled space and microbial activity is at minimum, pesticides, insecticides and herbicides are not needed."

In most hydroponic systems, the nutrient solutions include inorganic salt fertilizers and semi-soluble organic materials such as bat guano (manure), bone meal and fish emulsion. Since growing hydroponically does not require chemical fertilizers and pesticides, the method is inherently "organic," although the federal government doesn’t recognize it as such officially. Hydroponic farmers are trying to get the U.S. Food & Drug Administration to take soil out of the equation when it comes to defining organic so that their products can bear an organic certification label on store shelves and appeal to a quickly growing segment of green-minded consumers.

Hydroponic methods are becoming especially popular with a new wave of green-minded urban gardeners. When artist Britta Riley began growing her own food hydroponically in the window of her fifth floor Brooklyn apartment in 2009—and sharing her findings with like-minded folks all over the world via the Internet—the Windowfarms Project was born. In less than two years, some 13,000 people have joined the online community at the windowfarms.org website, where members can download free how-to instructions for homemade hydroponic systems.

Along with the Windowfarms Project website, a couple of good sources of hydroponic growing information, inspiration and supplies include Hydroponics Online and Simply Hydroponics and Organics.

CONTACTS: E — The Environmental Magazine; The Windowfarms Project; Hydroponics Online; Simply Hydroponics and Organics.

Dear EarthTalk: Can pollution affect my child’s IQ?

—Ellen Franzen, Portland, OR

A spate of recent studies suggests that pollution can indeed affect the intelligence of children of all ages (even those still in utero). The primary culprit is smog—ground level pollution comprised of vehicle and smokestack emissions that can form a dense haze on and near busy roadways. While smog has long been known to be a health hazard for asthmatics, heart patients and the elderly, only recently have we begun to learn about its unique effects on our young people.

A 2007 Harvard School of Public Health study found that children between the ages of eight and 11 living and attending school in areas of Boston with higher levels of traffic pollutants scored an average of 3.7 points lower on IQ tests than children living in less polluted areas. "The effect of pollution on intelligence was similar to that seen in children whose mothers smoked 10 cigarettes a day while pregnant, or in kids who have been exposed to lead," reports Dr. Shakira Franco Suglia, lead author of the study.

A 2009 Columbia Center for Children’s Environmental Health study of the effect over a five-year period of exposure to polycyclic aromatic hydrocarbons (PAHs)—toxic pollutants that come from the combustion of coal, diesel or gas—showed even greater effects on the offspring of expecting mothers living in parts of Harlem and the Bronx in New York City. Researchers found that those children exposed to the highest amounts of PAH pollution had IQs some 4.31 to 4.67 lower than non-exposed kids.

"These findings are of concern because these decreases in IQ could be educationally meaningful in terms of school performance," says Frederica Perera, the study’s lead author and the Columbia Center’s director, adding that the effects of PAHs were similar to the findings of the damage caused by low-level lead exposure. "This finding is of concern because IQ is an important predictor of future academic performance, and PAHs are widespread in urban environments and throughout the world."

Several other U.S. and international studies in 2009 and 2010 found evidence suggesting that common urban pollutants affect more than just intelligence in kids. Frequent exposure has also been linked to low birth weight and small head circumference as well as miscarriage and preeclampsia (hypertension during pregnancy). "Some researchers believe that traffic pollution acts like secondhand smoke or marijuana use, restricting oxygen and nutrients delivered to the fetus," reports Hilary Evans in E — The Environmental Magazine, adding that others believe that prenatal exposure to pollutants changes human cell development and causes problems later in life.

Columbia’s Perera is optimistic that we can work our way out of such problems. "Fortunately, airborne PAH concentrations can be reduced through currently available controls, alternative energy sources and policy interventions," she says. Indeed, urban planners, regulators and eco-entrepreneurs are experimenting with different methods of reducing smog and other pollutants in problem areas. But until such techniques are perfected and clean-up mandates enforced, those living near busy roadways or otherwise polluted areas put their families at risk every time the front door opens.

CONTACTS: Harvard School of Public Health; Columbia Center for Children’s Environmental Health.

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A window farm in Brooklyn, NY © Julia Makarova