Dear EarthTalk: What are the environmental benefits of the hydroponic growing of lettuce and other crops? — Bruce Keeler, Oakland, CA

Hydroponic growing not only eliminates the need for chemical fertilizers and pesticides but also takes up much less space than traditional agriculture, meaning that even an apartment window can yield impressive amounts of food throughout the calendar year. (Media credit/Ars Electronica, The Window Project)

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, www.emagazine.com/view/?5221; The Windowfarms Project, www.windowfarms.org; Hydroponics Online, www.hydroponicsonline.com; Simply Hydroponics and Organics, www.simplyhydro.com.

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, www.hsph.harvard.edu; Columbia Center for Children’s Environmental Health, www.cumc.columbia.edu/dept/mailman/ccceh.

SEND YOUR ENVIRONMENTAL QUESTIONS TO: EarthTalk®, c/o E – The Environmental Magazine, P.O. Box 5098, Westport, CT 06881; earthtalk@emagazine.com. E is a nonprofit publication. Subscribe: www.emagazine.com/subscribe; Request a Free Trial Issue: www.emagazine.com/trial.

Dear EarthTalk: I want to start an organic vegetable garden in my yard and I would like to know how to combine crops to make better use of time and space. – Val Thomason, Denton, TX

Most commercial farms concentrate on growing a few select crops to supply a wide variety of customers, but gardening at home is a different story entirely. Most backyard food gardeners are looking to augment their family’s diet with a variety of seasonal fruits, vegetables and herbs throughout the growing season.

For those of us who face time and space constraints in our gardening endeavors, combining crops within the same planting areas makes a lot of sense. Such techniques are particularly well-suited to organic gardens where chemical fertilizers and pesticides aren’t used to artificially boost crop productivity.

The most common way to combine garden crops is via an age-old technique called interplanting, which in essence means planting various garden edibles with different growth and spacing attributes together in the same soil beds or rows. One example involves combining fast-maturing vegetables, such as lettuce, field greens or beets, with slower-maturing ones like winter squash or pole beans. According to the informational “Our Garden Gang” website, mixing tall plants, like sweet corn, peas or staked tomatoes, with low-growing crops such as melons or radishes, is another way to maximize diversity and yield.

Building on the idea of interplanting, Better Homes & Gardens magazine suggests that gardeners combine plants that produce vines and can be grown on trellises or fences along with low-growing crops. So-called “vertical gardening” concentrates much more production into each square foot of planting area. Also, the magazine reports, crops grown off the ground “tend to be healthier because they are less likely to contract fungus infections or soil-borne leaf diseases.” Tomatoes, pole beans, cucumbers, snap peas, melons and winter squash are all examples of crops suitable for vertical gardening if staked or supported properly.

Another common technique often employed by “weekend” gardeners, organic or otherwise, is succession planting, which entails replacing a finished crop with a different one, or planting a single crop in small amounts over an extended period of time. One example would be to replace a spring crop with a summer crop, such as planting cucumbers-which thrive in warmer weather-where the peas had been growing earlier. Another form of succession planting involves staggering the planting of seeds from one specific crop throughout its growing season to ensure a continuing supply as long as possible.

Some crops particularly well-suited to succession planting include bush beans, lettuce, spinach and radishes, each of which have long growing seasons but can be harvested after only a few weeks. A related technique would be to plant both early- and late-maturing varieties of the same type of crop around the same time, and harvesting the resulting crops successively. Tomatoes and corn, for example, each come in varieties that ripen at different times during their respective growing seasons.

And while it may be easy to get carried away with edible gardening, don’t forget to plant a few flowers to spruce up the look of your garden and also attract bees to help pollinate your food crops. Marigolds and sunflowers are good choices as they are relatively easy to grow organically and tend to attract lots of bees.

CONTACTS: Our Garden Gang, http://ourgardengang.tripod.com; Better Homes & Gardens, www.bhg.com.

Dear EarthTalk: Are there any flea and tick products out there that don’t contain toxic chemicals?

–Ewan Locke, Madison, WI

Harmful pesticides in mainstream flea and tick products are indeed hazardous to more than insects. The active substance in most of these products is likely one of seven common organophosphate insecticides (OPs), which work by interfering with the transmission of nerve signals in the brains and nervous systems of not just insects-most of whom die on the spot-but to a lesser degree in pets and humans as well. While it would certainly take an awful lot of exposure to OPs to affect a full-grown healthy human adult, no one is sure how the chemicals might affect children or those with pre-existing nerve disorders.

The non-profit Natural Resources Defense Council (NRDC), which authored the 2000 report “Poisons on Pets” (results are online at the group’s GreenPaws.org website), reports that “studies with lab animals have raised concerns among scientists that children exposed to certain of the pesticides in pet products-even at levels believed to be safe for adults-face much higher risks, not only for acute poisoning, but also for longer-term problems with brain function and other serious disease.” The group adds that children’s behavior-notably toddlers’ hand-to-mouth tendencies and the fact that kids play where such toxins often accumulate-makes them more vulnerable to ingesting OPs than adults in the same household.

The magnitude of the potential risk to public health is what makes the inclusion of such chemicals in pet products so troubling: Surveys show that as many as 50 percent of American families report using some kind of flea and tick control product on pets, subjecting untold millions of children to toxic chemicals on a daily basis. Initial research also shows that thousands of pets may be sickened or die each year as a result of chronic low-dose exposure to OPs through their flea and tick collars.

Fortunately, several non-toxic alternatives to OP-laden flea and tick control products are now available. NRDC tested upwards of 125 pet-oriented flea and tick control products for its Poisons on Pets report and found less than two dozen that don’t contain harmful chemical compounds. Stripe-On formulations from Adams, Breakthru, Demize and Scratchex get high marks from NRDC for low-toxicity, while tabs (pills) from Comfortis, Program and Sentinel also make the safety grade. Hartz, which uses OPs in most of its product line, also offers some safer formulations (Spot-On, Advanced Care and Ultra Guard) for cats and kittens. These products rely on insect growth regulators, which arrest the growth and development of young fleas, rather than pesticides to simply kill them. NRDC notes, however, that even these safer formulations contain chemicals, and that all such products should be used with caution.

One way to treat your pet but avoid chemicals altogether is to go the essential oil route.‚  Oils from cedarwood, lemongrass, peppermint, rosemary or thyme have all been shown to be effective, when used sparingly, to keep fleas and ticks away from pets and their favorite haunts. Of course, a little conscientious legwork can obviate the need for any kind of topical or pill-based flea and tick control products, toxic or otherwise. According to NRDC, frequent washing and combing of pets and vacuuming carpets and furniture can bring mild flea infestations under control and help avoid outbreaks altogether.

CONTACT: NRDC Green Paws, www.greenpaws.org; Scratchex, www.scratchex.com; Sentinel, www.sentinelpet.com; Comfortis, www.comfortis4dogs.com; Hartz, www.hartz.com.

SEND YOUR ENVIRONMENTAL QUESTIONS TO: EarthTalk, P.O. Box 5098, Westport, CT 06881; earthtalk@emagazine.com. Read past columns at: www.emagazine.com/earthtalk/archives.php. EarthTalk is now a book! Details and order information at: www.emagazine.com/earthtalkbook.