CAN FOOD CROPS BE GROWN SAFELY IN PLASTIC CONTAINERS? (Willem Van Cotthem)

Some gardeners fear that growing vegetables or herbs in plastic containers (bottles, pots, buckets and the like) could be dangerous because of the supposed leaching of Bisphenol A (BPA), and the “possibility” that this leached BPA could be absorbed by the plants, rendering them  “toxic” for human consumption.

Concerning the possible danger of using plastic containers for plant production, one should be looking for irrefutable scientific proof of the presence of BPA in food crops grown in such containers.  The fact is that, to the best of my knowledge, no such evidence exists in scientific literature.

annelies_wauters_006AGrowing strawberries in bucket towers with support of the Luminus Company (Photo WVC)

Some publications on BPA

(1) What is BPA, and what are the concerns about BPA?

Answer from Katherine Zeratsky, R.D., L.D.

http://www.mayoclinic.com/health/bpa/AN01955

BPA stands for bisphenol A. BPA is an industrial chemical that has been used to make certain plastics and resins since the 1960s.  In particular, BPA is found in polycarbonate plastics and epoxy resins. Polycarbonate plastics are often used in containers that store food and beverages, such as water bottles, and baby bottles and cups. They may also be used in toys and other consumer goods.

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Some research has shown that BPA can seep into food or beverages from containers that are made with BPA or into your body when you handle products made with BPA. BPA remains controversial, and research studies are continuing. The American Chemistry Council, an association that represents plastics manufacturers, contends that BPA poses no risk to human health.

But the National Toxicology Program at the Department of Health and Human Services says it has “some concern” about the possible health effects of BPA on the brain, behavior and prostate gland of fetuses, infants and children. This level of concern is midway on its five-level scale, which ranges from serious to negligible. The Food and Drug Administration now shares this level of concern and is taking steps to reduce human exposure to BPA in the food supply by finding alternatives to BPA in food containers.”

(2) Plastic Bottles Release Potentially Harmful Chemicals (Bisphenol A) After Contact With Hot Liquids

http://www.sciencedaily.com/releases/2008/01/080130092108.htm

“Feb. 4, 2008 — When it comes to Bisphenol A (BPA) exposure from polycarbonate plastic bottles, it’s not whether the container is new or old but the liquid’s temperature that has the most impact on how much BPA is released, according to University of Cincinnati (UC) scientists.

Scott Belcher, PhD, and his team found when the same new and used polycarbonate drinking bottles were exposed to boiling hot water, BPA, an environmental estrogen, was released 55 times more rapidly than before exposure to hot water.

“…………….. BPA can migrate from various polycarbonate plastics,” explains Belcher…………but we wanted to know if ‘normal’ use caused increased release from something that we all use, and to identify what was the most important factor that impacts release.”

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The chemical–which is widely used in products such as re-usable water bottles, food can linings, water pipes and dental sealants–has been shown to affect reproduction and brain development in animal studies.

“There is a large body of scientific evidence demonstrating the harmful effects of very small amounts of BPA in laboratory and animal studies, but little clinical evidence related to humans,” explains Belcher. “There is a very strong suspicion in the scientific community, however, that this chemical has harmful effects on humans.”

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The UC researchers found that the amount of BPA released from new and used polycarbonate drinking bottles was the same — both in quantity and speed of release — into cool or temperate water.  However, drastically higher levels of BPA were released once the bottles were briefly exposed to boiling water.

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Belcher stresses that it is still unclear what level of BPA is harmful to humans. He urges consumers to think about how cumulative environmental exposures might harm their health.

“BPA is just one of many estrogen-like chemicals people are exposed to, and scientists are still trying to figure out how these endocrine disruptors–including natural phyto-estrogens from soy which are often considered healthy–collectively impact human health,” he says. “But a growing body of scientific evidence suggests it might be at the cost of your health.”

(3) Ban BPA? No Chance, Says FDA

How you can protect your family from the chemical

By Emily Main (2012-03)

http://www.prevention.com/health/healthy-living/breaking-news-fda-will-not-be-banning-bpa#ixzz2LHddD8Wn

“Much to the chagrin of public health advocates, the Food and Drug Administration (FDA) has just announced its decision not to ban the controversial chemical bisphenol A in baby bottles, canned food, infant formula cans, or any other use in which the chemical comes into direct contact with your food. 

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Best BPA-Free Water Bottles  

Here’s what the FDA says about its decision: “The FDA denied the NRDC petition today because it did not provide the scientific evidence needed to change current regulations,” says FDA spokesman Douglas Karas in a prepared statement. “But this announcement is not a final safety determination and the FDA continues to support research examining the safety of BPA.” The agency went on to say that, although they have been studying the effects of BPA for years, none of their existing studies show enough evidence to force them to change their official position on the chemical’s safety.

That’s hardly reassuring to NRDC public health scientists. “BPA is a toxic chemical that has no place in our food supply. We believe the FDA made the wrong call,” says Sarah Janssen, senior scientist at NRDC. “The FDA is out-of-step with scientific and medical research. This illustrates the need for a major overhaul of how the government protects us against dangerous chemicals.”

(4) F.D.A. Makes It Official: BPA Can’t Be Used in Baby Bottles and Cups

By SABRINA TAVERNISE

Published: July 17, 2012

http://www.nytimes.com/2012/07/18/science/fda-bans-bpa-from-baby-bottles-and-sippy-cups.html?_r=0

“WASHINGTON — The Food and Drug Administration said Tuesday that baby bottles and children’s drinking cups could no longer contain bisphenol A, or BPA, an estrogen-mimicking industrial chemical used in some plastic bottles and food packaging.

Manufacturers have already stopped using the chemical in baby bottles and sippy cups, and the F.D.A. said that its decision was a response to a request by the American Chemistry Council, the chemical industry’s main trade association, that rules allowing BPA in those products be phased out, in part to boost consumer confidence.

But the new prohibition does not apply more broadly to the use of BPA in other containers, said an F.D.A. spokesman, Steven Immergut. He said the decision did not amount to a reversal of the agency’s position on the chemical. The F.D.A. declared BPA safe in 2008, but began expressing concerns about possible health risks in 2010.

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BPA has been used since the 1960s to make hard plastic bottles, cups for toddlers and the linings of food and beverage cans, including those that hold infant formula and soda. Until recently, it was used in baby bottles, but major manufacturers are now making bottles without it. Plastic items containing BPA are generally marked with a 7 on the bottom for recycling purposes.

The chemical can leach into food, and a study of over 2,000 people found that more than 90 percent of them had BPA in their urine. Traces have also been found in breast milk, the blood of pregnant women and umbilical cord blood.

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The American Chemistry Council said in a statement that it had asked the F.D.A. to take action because of confusion, stirred by state legislative and regulatory actions, about whether baby bottles and cups for toddlers contain BPA. It said that manufacturers announced years ago that they had stopped using the chemical in those items.”

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Vertical gardening in small spaces : Towers of bottles and pots producing vegetables and herbs with a minimum of water, simply using local dirt and manure (Photo WVC)

Vertical gardening in small spaces : Towers of bottles and pots producing vegetables and herbs with a minimum of water, simply using local dirt and manure (Photo WVC)

As some people continue to ask me about the safety of growing food crops in plastic containers, I submitted the following question to ResearchGate https://www.researchgate.net/

If BPA or BPS is leaching from plastic containers filled with soil, is this toxic substance absorbed by food crops growing in those containers?

Here are some of the key points from the responses, along with additional comments from me:

Farid El-Daoushy · Uppsala University – Department of Physics and Astronomy
That depends on the organic content of the soils. High organic content can help screening pollutants and toxic compounds from water through chelation. This self-cleaning mechanism of soils with high organic content can act as natural filters and thereby protect plants against pollution”.

Willem Van Cotthem · University of Ghent – Department of Botany
“I would like to know if cultivating food crops in recycled plastic containers poses a potential danger to public health.  If BPA (or BPS) does leach into water (or into the soil solution inside plastic containers), the question remains if the leached BPA can be absorbed by roots growing in the soil within the container.  Of course, if the leaching of BPA (or BPS) into drinks sold in “unsafe” plastic bottles posed a health risk, the use of those bottles would have been banned a long time ago. Since they are still in widespread use, however, one can conclude that it is safe to use them for food crop cultivation as well.

Reed Benkendorf · University of Illinois, Urbana-Champaign School of Integrative Biology
Is BPA actually leached from any of these plastics? If so, does humic acid complex it? If not, and BPA is absorbed by the roots, does it pass through the Casparian strip in the endodermis cells? Some plants have a pronounced ability to accumulate toxins in the cortex but do not transport them further.”

David Dunn · commercial horticulture
Many crops are grown in plastic containers of various sorts, especially greenhouse crops with hydroponic and/ or substrate systems, employing more plastics or glass wool and/or with peat mixtures.  Most crops rely on plastics for delivery of water and fertilizer to plants and as mentioned above some organic teas are sometimes used employing highly complex acids, especially in protected cropping which may cause leaching from the plastics employed.  If there is a problem then it needs to be addressed quickly to allay fears of the public.

John Chater · University of California, Riverside Department of Botany and Plant Sciences
BPA is a relatively large (and non-polar) molecule compared to the ions that plants typically are taking up (K+, N03-, Mg++, … ),  so I do not think that the plant will take up the BPA (which has two phenol-groups in the structure).  There is theoretically no way for the soil’s BPA to get into the crop.  Remember, all materials need to pass through the Casparian strip in order to make it through the root’s endodermis and into the vasculature.

Willem Van Cotthem · University of Ghent
It seems difficult, if not impossible, for a large, non-polar molecule like BPA to be absorbed by root-hair cells and transported towards all plant parts. If that were the case, would there not be accumulation somewhere in the plant body?  An additional question is: Does leaching of BPA occur at ambient temperatures in the environment (including full sunshine)? As many food crops (vegetables and herbs) have been grown for decades already in a wide variety of plastic containers it seems that if BPA were leaching and transported into the crops, traces of BPA would commonly be found in the crops, as well as in the humans who consume them. No such evidence exists and no such link has been established. I am still concerned about how the general public seems to draw a connection between the potential presence of BPA in plants growing in plastic containers (“safe” and “unsafe” plastics), and the potential presence of BPA in drinks sold in plastic bottles.”

Peter Knop · Ticonderoga Arboretum and Botanical Gardens
I am surprised that no one has mentioned the enormous amount of plastic used in row cropping and the millions of tons of produce grown on such plastic. It totally dwarfs hydroponics or other container grown crops. Maybe the term “container” includes these, as for the bottom of the raised beds the entire root system is exposed to this plastic mulch. This leads to another interesting problem: some of these mulches are biodegradable and their chemicals, like binders, become part of the soil.  Aren’t they dangerous?

Willem Van Cotthem · University of Ghent
Indeed, heaps of plastic sheets are used in agri- and horticulture, even biodegradable ones. If all those plastics, or only the “unsafe” ones, are leaching dangerous, toxic elements into the environment, we are probably “doomed”.

Debi Sharma · Indian Institute of Horticultural Research
If leaching of BPA is higher at higher temperatures then it is a matter of concern especially in tropical conditions.”

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Combating malnutrition with vertical gardening in bottle towers.  Masses of food on a few square feet with only a bit of water.  Can you do better ?  Then show us. (Photo WVC)

Combating malnutrition with vertical gardening in bottle towers. Masses of food on a few square feet with only a bit of water. Can you do better ? Then show us. (Photo WVC)

Based on the responses I have received to the question I have put to ResearchGate, no clear proof has been provided that BPA or BPS is leaching into the soil in which plants are growing, or that BPA or other toxic substances are absorbed into those plants.

Is it really dangerous to grow food crops in plastic containers? 

Let us have a look at a recent publication in Science Daily(2013/02):

http://www.sciencedaily.com/releases/2013/02/130217084541.htm

A scientific analysis of 150 studies in which human beings have been exposed to “low dosages of BPA” shows that “in the general population, people’s exposure may be many times too low for BPA to effectively mimic estrogen in the human body.

The analysis of 130 toxicity studies of BPA showed:

“………………….that a small fraction of the “low doses” used in these studies are within the range of human exposures, with the vast majority being at least 10 to thousands of times higher than what humans are exposed to daily. In addition, the range of concentrations spans from upwards of 10 grams per kilogram of weight per day down to 100 picograms per kilogram of weight per day (a picogram is one millionth of a gram).

Unfortunately, the low dose moniker has been used by some to promote the importance of selected toxicity studies, for example, in arguments to ban BPA,” said Teeguarden. “For BPA and all chemicals, we need more accurate language to present these findings so the public and scientists in other disciplines can understand how human exposures compare to exposures in laboratory studies reporting toxicity.

Although I am more convinced than ever that it is safe to grow plants in plastic containers, I would still like to obtain conclusive answers to the following two questions:

(1) Is BPA (or BPS), within ambient environmental temperatures (even in sunshine), really leaching in any notable concentrations from the plastic bottles, pots or buckets in which we grow our fresh food?

(2) If so, are plants absorbing it in such concentrations that eating them poses a danger to public health?

Expecting that one day we will be able to find the answers based on long-term, independent scientific studies, I continue for now to promote my bottle tower method (http://youtu.be/JtbOREs2kIo) as a particularly effective way to combat malnutrition, hunger and poverty in developing countries.

Growing fresh food in recycled containers on a bottle rack in The Philippines.  A technique that can be by all the hungry people of this world (Photo Jojo ROM)

Growing fresh food in recycled containers on a bottle rack in The Philippines. A technique that can be by all the hungry people of this world (Photo Jojo ROM)

As long as all the specialists-experts of the world scrutinize every day the production and sales of food and drinks in plastic containers, as long as they allow millions of people to eat and drink from plastic containers, I will continue to believe that the fresh food we produce in the same containers constitutes no direct danger for public health.

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About Willem Van Cotthem

Honorary Professor of Botany, University of Ghent (Belgium). Scientific Consultant for Desertification and Sustainable Development.
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