Hydroponic Growing Systems….A Threat to Students

Studies and Effects of Hydroponic Fertilizer

Hydroponics is a method of cultivating plants using a fertilizer nutrient solution and water without soil. The popularity of this technique stems from the fact our food supply is increasingly stressed and the need to grow food faster is in order to keep up with demand. Hydroponic techniques can provide year round growing opportunities and ease the stress placed on traditional soil but this comes with a cost. Foremost Hydroponic growing lacks the natural processes found in compost such as the biological activity between plants and bacteria and the benefits of humic acid contributing to the nutrient quality and the increased brix levels of produce grown in compost. The Hydroponic technique requires a fertilizer solution that provides macro and micro nutrients required for plant growth. The fertilizer solutions are concocted from a myriad of chemicals derived from ammonium molybdate, ammonium phosphate, calcium nitrate, cobalt sulfate, copper sulfate, iron DTPA, magnesium sulfate, manganese sulfate, potassium borate, potassium nitrate, potassium phosphate, and zinc sulfate.
*If you are teaching hydroponics in the NYC school system, according to the New York City Department of Education (NYCDOE) “Science Safety Manual K-12”(1) scales for health and safety must be in compliance with the Federal OSHA standards(2) and material data safety sheets also listing categories and levels of hazards for chemicals.
Man-made fertilizers became widely used in U.S. agriculture after WWII, providing an inexpensive source of plant nutrients that resulted in huge increases in agricultural productivity yet increased fertilizer use contributed to profound changes to the global nitrogen cycle that rival human effects on the carbon cycle. According to the United States Environmental Protection Agency (EPA) nitrates and nitrites are chemicals used in fertilizers has been reported to have adverse health effects. Nitrates convert to nitrosamines, which have been shown to cause tumors in laboratory animals. Nitrate-contaminated water is also linked to reproductive problems, urinary and kidney disorders, and bladder and ovarian cancer. Besides seriously depleting the nutritional content of food, direct contact or exposure to synthetic chemical fertilizers can kill infants or cause health problems in many adults. Studies show exposure can increased risk of cancer and other health problems.(3)
Also, if you have any type of urinary, kidney, or liver health difficulties, you should especially avoid any type of exposure. The adverse effects of synthetic chemical fertilizers are often underplayed and ignored despite their damage being far reaching. Synthetic fertilizers can cause a vast array of symptoms, some immediate, some signs showing up later, some effects on people and animals are direct, and some effects are indirect.(4)
A 1996 research project studied cancer rates among over 600 people. Brain cancer overall showed a two fold increase risk for people living within the 2600 foot distance of an agricultural area. An astounding 6.7 fold increased risk was found for the brain cancer type known as astrocytoma. For more information on brain cancer and neuroblastoma see:
www.chem-tox.com/cancerchildren.- brain cancer research summaries
www.chem-tox.com/neuroblastoma – neuroblastoma research summaries
Drs. A. Aschengrau, D. Ozonoff, P.Coogan, R. Vezina, T. Heeren
Department of Epidemiology and Biostatistics
Boston University School of Public Health

What most do not realize is that fertilizer does not have to be ingested. Most of the damage for synthetic fertilizers, insecticides, fungicides and herbicides comes from what is absorbed through the skin. In the case of utilizing hydroponic growing in the classroom the techniques should be treated as a chemistry class and not a novel indoor garden lesson.
The National Research Council states that 6 out of the top 7 and 9 out of the top 15 foods with oncogenic (cancer causing) risk are produced from food containing high amounts of nitrates from fertilizers. A twelve year study showed that foods grown using chemicals had 16 times the amount of nitrate, which is a carcinogen, than organically grown ones.(5)
The biggest drawback to hydroponics is that the nutrients used in the solutions are most often made from synthetically derived, refined mineral salts. These fertilizers are commonly created through industrial-based processes. Therefore, most hydroponics cannot be considered “organic,” as USDA National Organic Program standards only allow for the use of unprocessed, mined mineral or animal-based fertilizers, such as rock dust, blood meal, bone meal and animal manures. Many organic fertilizers can’t be used in hydroponics because their nutrients are generally not water-soluble. Certain critical nutrients, particularly phosphorus and potassium, are typically absent in aqueous solutions. While there are hydroponic solutions marketed as ‘organic’ that contain a predominance of natural materials, they should be carefully checked to ensure that no synthetic ingredients are included.(6) Organic hydroponic growing is virtually nonexistent.


Classroom Use of Hydroponic Solutions

MEWUThere has been a growing popularity and awareness for food security, locally grown food, know your farmer, organic and hydroponic growing. The subject lends itself to multiple teaching opportunities through a STEM (Science Technology Engineering and Math) like philosophy. Traditionally the school garden is subject to a month or two of real learning while the students and staff dismiss for the summer the support staff of building maintenance is left to tend the garden or let it perish. Rhetorically speaking where is the culminating activity of harvest?
Bringing the school garden indoors can associate lessons to existing curriculum. The popularity of the 70’s lesson plan included a bean or corn seed in a cardboard milk carton line up along a window in the classroom. This lesson plan was trumped by the introduction of the Mobile Edible Wall Unit (MEWU) (Left) via Green Living Technologies International LLC (GLTi) starting in a Los Angeles School Miguel Contreras High School grew Celery in the vertical farm (compost) outside the classroom. The MEWU and the GLTi education guide were the instrumental tools for the GLTi “Train the Trainer Program” in a Bronx classroom at the Discovery High School that boasted 100% graduation rates and an increase of 43% to 93% attendance for four years in a row.
The popularity of growing your own food coupled with teaching opportunities led to the use of hydroponic growing in the classroom. Theoretically it was a pretty simple application, mixing up fertilizer solution in water, a pump to recirculate the water and a timer. The hydroponic method relies on a fertilizer base solution that poses multiple threats to the environment and the students.
A hydroponic system is either:
1. Closed loop, where the chemically infused water is housed in a reservoir and pumped through the system. This application requires the disposal and cleaning of the reservoir on average every two weeks.
2. Drain to waste system introduces fertilizer and water through a single source and any excess during any one cycle is funneled to a drain.
Environmentally speaking both techniques require the need to dispose of the water with fertilizer. In a classroom situation it is safe to say the contaminated water is being dumped into the nearest drain under the premise there is not a hazardous waste disposal facility at the school or a contracted service to remove the waste water.
These nutrients are highly soluble nitrate, phosphate and salts they should be treated in the same way as industrial fertilizers. This excess fertilizer, disposed of through the classroom sink, will now move through the soil and in to the ground water supplies.
The New York City Department of Education (NYCDOE) “Science Safety Manual K-12” 4 specifically explaining the procedure for the disposal and discarding of chemicals.
Nitrates lower the ability of the red blood cells to carry and deliver oxygen (EPA, 2012)6. Teachers if your students are in;
Physical contact with plant fertilizers, they may develop the following symptoms:
• skin redness
• burning sensation on the skin
• itchy skin
• burning of the nose, eyes, or throat

If they ingest plant fertilizers, they may have these symptoms:
• body parts (such as your fingernails, lips, or hands) turning blue from lack of oxygen
• dizziness
• fainting
• low blood pressure
• seizures
• shortness of breath
• upset stomach or stomach pain

Teaching Hydroponics in the New York City Schools?

New York City Department of Education (NYCDOE) “Science Safety Manual K-12” scales for health and safety must be in compliance with the Federal OSHA standards2. OSHA has a specific link to Fertilizer Industry Guidance on Storage and Use of Ammonium Nitrate(7) regulating the storage of Ammonium Nitrate. In support of the NYCDOE OSHA Standards and the “Science Safety Manual K-12” students and teachers are required to wear personal protective equipment including:
• Goggles or face shield
• Hand protection suitable and rated for the use with fertilizer applications
• Protective clothing
• Respirators as suggested

According to multiple MSDS (Materials Safety Data Sheet) for hydroponic solutions:
• Do not breathe vapor or mist. Do not ingest. Use only with adequate ventilation. Do not eat, drink or smoke when using this product. Avoid contact with eyes, skin and clothing. Keep away from clothing and other combustible materials. Store in tightly-closed container.
• This material is considered hazardous by the OSHA Hazard Communication Standard (29 CFR 1910.1200)
• Moderately irritating to the respiratory system. Exposure to decomposition products may cause a health hazard. Serious effects may be delayed following exposure
• Causes damage to the following organs: blood, mucous membranes, cardiovascular system, and skin.
• Contains material which may cause damage to the following organs: upper respiratory tract
A larger list of MSDS by brand name are compiled here for additional reference.


Kids HydroVarious government agencies, university and health organizations confirm the findings of human exposure to fertilizer. Fertilizer in the classroom due to hydroponic growing is a severe short and long term threat to the health of the students that can result in immediate and extended consequences. Countless social media posts and pictures of student participation or assumed participation demonstrate teacher neglect while using hydroponic solutions.(LEFT: Students interacting with hydroponic chemicals void of OSHA approved protective equipment are subject to absorption through the skin and risk the solution splashing into their eyes.)

1 https://www.uft.org/files/attachments/doe-science-safety-manual.pdf
2 www.osha.gov
3 http://www.epa.gov/teach/chem_summ/Nitrates_summary.pdf
4 http://www.turfprousa.com/health_effects_of_synthetic_fertilizer_3006a.html
5 http://www.urbanfarmonline.com/urban-gardening/backyard-gardening/hydroponics.aspx
6 http://www.epa.gov/agriculture/ag101/impactnitrate.html
7 https://www.osha.gov/dep/fertilizer_industry/index.html

About the Author

George Irwin is the founder and President of Green Living Technologies International LLC (GLTi), a privately held company that manufactures Green Living Walls, Green Living Roofs. It is also the global pioneer in vertical agriculture with a focus on education & training. A published author and featured “Green Wall Editor”, George is also a leading resource and authority for green wall and roof technologies around the world. TIME, Fortune & Profit magazine, CNN, NBC, ABC, National Geographic, Newsweek, the Los Angeles Times and the New York Times are among the major media to feature stories about George and GLTi.
Prior to founding GLTi, George was a landscape contractor for over two decades. He holds a degree in education and maintains his passion for out-of-the-box learning, combining his love for the environment and zest for learning into a growing global business. George personally oversees all green wall and roof education, integrating his state-of-the-art technology and ideas into a continuously evolving educational and training curriculum. Annually, he teaches hundreds of new green technology experts in green roof manufacturing, installation, growth, and maintenance. His efforts have earned him recognition as one of the educational partners for the New York City Department of Education and an association with multiple higher education facilities and universities, resulting in the development of a dedicated degree track in “Green Tech” and STEM (Science Technology Engineering and Math) education at the middle and secondary school levels. George is the de facto leader in Green Education with anticipated long-term commitments from leading colleges and graduate programs coast-to-coast.
His vision extends well beyond achieving his own entrepreneurial aspirations: His mission is to help create sustainable solutions to the challenges of food insecurity and the dearth of job opportunities for at-risk youth in America’s inner cities. His technology is quickly replacing complex mechanical systems and hydroponics with simple growing techniques that can be replicated on any scale. Research studies have been underway to measurably prove just how economically viable and productive his state-of-the-art systems are for maximizing the growth of food year-round.
George Irwin may be contacted by e-mail at george@agreenroof.com for speaking engagements, classes, and keynotes.