Can food crops be grown safely in plastic containersDocument Transcript
CAN FOOD CROPS BE GROWN SAFELY IN PLASTIC CONTAINERS? By Prof. Dr. Willem VAN COTTHEM Botany Department University of Ghent (Belgium)http://desertification.wordpress.com/2013/02/23/can- food-crops-be-grown-safely-in-plastic-containers- willem-van-cotthem/Some gardeners fear that growing vegetables or herbsin plastic containers (bottles, pots, buckets and the like)could be dangerous because of the supposed leaching ofBisphenol A (BPA), and the "possibility" that this leachedBPA could be absorbed by the plants, rendering them"toxic" for human consumption.Concerning the possible danger of using plasticcontainers for plant production, one should be lookingfor irrefutable scientific proof of the presence of BPA infood crops grown in such containers. The fact is that, tothe best of my knowledge, no such evidence exists inscientific literature.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 industrialchemical that has been used to make certain plastics andresins since the 1960s.In particular, BPA is found in polycarbonate plastics andepoxy resins. Polycarbonate plastics are often used incontainers that store food and beverages, such as waterbottles, and baby bottles and cups. They may also beused in toys and other consumer goods.………………….Some research has shown that BPA can seep into food orbeverages from containers that are made with BPA orinto your body when you handle products made withBPA. BPA remains controversial, and research studiesare continuing. The American Chemistry Council, anassociation that represents plastics manufacturers,contends that BPA poses no risk to human health.But the National Toxicology Program at the Departmentof Health and Human Services says it has "someconcern" about the possible health effects of BPA on thebrain, behavior and prostate gland of fetuses, infants andchildren. This level of concern is midway on its five-levelscale, which ranges from serious to negligible. The Foodand Drug Administration now shares this level ofconcern and is taking steps to reduce human exposure toBPA in the food supply by finding alternatives to BPA infood containers.”
(2) Plastic Bottles Release Potentially HarmfulChemicals (Bisphenol A) After Contact With Hot Liquidshttp://www.sciencedaily.com/releases/2008/01/080130092108.htm“Feb. 4, 2008 — When it comes to Bisphenol A (BPA)exposure from polycarbonate plastic bottles, its notwhether the container is new or old but the liquidstemperature that has the most impact on how muchBPA is released, according to University of Cincinnati(UC) scientists.Scott Belcher, PhD, and his team found when the samenew and used polycarbonate drinking bottles wereexposed to boiling hot water, BPA, an environmentalestrogen, was released 55 times more rapidly thanbefore exposure to hot water."…………….. BPA can migrate from various polycarbonateplastics," explains Belcher…………but we wanted to knowif normal use caused increased release from somethingthat we all use, and to identify what was the mostimportant factor that impacts release."…………………………….The chemical--which is widely used in products such asre-usable water bottles, food can linings, water pipesand dental sealants--has been shown to affectreproduction and brain development in animal studies.
"There is a large body of scientific evidencedemonstrating the harmful effects of very smallamounts of BPA in laboratory and animal studies, butlittle clinical evidence related to humans," explainsBelcher. "There is a very strong suspicion in the scientificcommunity, however, that this chemical has harmfuleffects on humans."…………………….The UC researchers found that the amount of BPAreleased from new and used polycarbonate drinkingbottles was the same -- both in quantity and speed ofrelease -- into cool or temperate water. However,drastically higher levels of BPA were released once thebottles were briefly exposed to boiling water.…………………………Belcher stresses that it is still unclear what level of BPA isharmful to humans. He urges consumers to think abouthow cumulative environmental exposures might harmtheir health."BPA is just one of many estrogen-like chemicals peopleare exposed to, and scientists are still trying to figure outhow these endocrine disruptors--including natural phyto-estrogens from soy which are often considered healthy--collectively impact human health," he says. "But agrowing body of scientific evidence suggests it might beat the cost of your health."
(3) Ban BPA? No Chance, Says FDAHow you can protect your family from the chemicalBy 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, theFood and Drug Administration (FDA) has just announcedits decision not to ban the controversial chemicalbisphenol A in baby bottles, canned food, infant formulacans, or any other use in which the chemical comes intodirect contact with your food.…………………………….Best BPA-Free Water BottlesHere’s what the FDA says about its decision: "The FDAdenied the NRDC petition today because it did notprovide the scientific evidence needed to change currentregulations,” says FDA spokesman Douglas Karas in aprepared statement. “But this announcement is not afinal safety determination and the FDA continues tosupport research examining the safety of BPA." Theagency went on to say that, although they have beenstudying the effects of BPA for years, none of theirexisting studies show enough evidence to force them tochange their official position on the chemicals safety.
Thats hardly reassuring to NRDC public health scientists."BPA is a toxic chemical that has no place in our foodsupply. We believe the FDA made the wrong call," saysSarah Janssen, senior scientist at NRDC. "The FDA is out-of-step with scientific and medical research. Thisillustrates the need for a major overhaul of how thegovernment protects us against dangerous chemicals."(4) F.D.A. Makes It Official: BPA Can’t Be Used in BabyBottles and CupsBy SABRINA TAVERNISEPublished: July 17, 2012http://www.nytimes.com/2012/07/18/science/fda-bans-bpa-from-baby-bottles-and-sippy-cups.html?_r=0“WASHINGTON — The Food and Drug Administrationsaid Tuesday that baby bottles and children’s drinkingcups could no longer contain bisphenol A, or BPA, anestrogen-mimicking industrial chemical used in someplastic bottles and food packaging.Manufacturers have already stopped using the chemicalin baby bottles and sippy cups, and the F.D.A. said thatits decision was a response to a request by the AmericanChemistry Council, the chemical industry’s main tradeassociation, that rules allowing BPA in those products bephased out, in part to boost consumer confidence.
But the new prohibition does not apply more broadly tothe use of BPA in other containers, said an F.D.A.spokesman, Steven Immergut. He said the decision didnot amount to a reversal of the agency’s position on thechemical. The F.D.A. declared BPA safe in 2008, butbegan expressing concerns about possible health risks in2010.……………………………BPA has been used since the 1960s to make hard plasticbottles, cups for toddlers and the linings of food andbeverage cans, including those that hold infant formulaand soda. Until recently, it was used in baby bottles, butmajor manufacturers are now making bottles without it.Plastic items containing BPA are generally marked witha 7 on the bottom for recycling purposes.The chemical can leach into food, and a study of over2,000 people found that more than 90 percent of themhad BPA in their urine. Traces have also been found inbreast milk, the blood of pregnant women and umbilicalcord blood.……………………………..The American Chemistry Council said in a statement thatit had asked the F.D.A. to take action because ofconfusion, stirred by state legislative and regulatoryactions, about whether baby bottles and cups fortoddlers contain BPA. It said that manufacturers
announced years ago that they had stopped using thechemical in those items.”------------------------------------------As some people continue to ask me about the safety ofgrowing food crops in plastic containers, I submitted thefollowing question to ResearchGatehttps://www.researchgate.net/If BPA or BPS is leaching from plastic containers filledwith soil, is this toxic substance absorbed by food cropsgrowing 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 ofPhysics and Astronomy“That depends on the organic content of the soils. Highorganic content can help screening pollutants and toxiccompounds from water through chelation. This self-cleaning mechanism of soils with high organic contentcan act as natural filters and thereby protect plantsagainst pollution”.Willem Van Cotthem · University of Ghent –Department of Botany“I would like to know if cultivating food crops in recycledplastic containers poses a potential danger to public
health. If BPA (or BPS) does leach into water (or into thesoil solution inside plastic containers), the questionremains if the leached BPA can be absorbed by rootsgrowing in the soil within the container. Of course, if theleaching of BPA (or BPS) into drinks sold in "unsafe”plastic bottles posed a health risk, the use of thosebottles would have been banned a long time ago. Sincethey are still in widespread use, however, one canconclude that it is safe to use them for food cropcultivation as well.Reed Benkendorf · University of Illinois, Urbana-Champaign School of Integrative Biology“Is BPA actually leached from any of these plastics? Ifso, does humic acid complex it? If not, and BPA isabsorbed by the roots, does it pass through theCasparian strip in the endodermis cells? Some plantshave a pronounced ability to accumulate toxins in thecortex but do not transport them further.”David Dunn · commercial horticulture“Many crops are grown in plastic containers of varioussorts, especially greenhouse crops with hydroponic and/or substrate systems, employing more plastics or glasswool and/or with peat mixtures.Most crops rely on plastics for delivery of water andfertilizer to plants and as mentioned above some organicteas are sometimes used employing highly complexacids, especially in protected cropping which may causeleaching from the plastics employed.
If there is a problem then it needs to be addressedquickly to allay fears of the public. “John Chater · University of California, RiversideDepartment of Botany and Plant Sciences“BPA is a relatively large (and non-polar) moleculecompared to the ions that plants typically are taking up(K+, N03-, Mg++, … , so I do not think that the plant willtake up the BPA (which has two phenol-groups in thestructure). There is theoretically no way for the soilsBPA to get into the crop. Remember, all materials needto pass through the Casparian strip in order to make itthrough the roots endodermis and into thevasculature.”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 cellsand transported towards all plant parts. If that were thecase, would there not be accumulation somewhere inthe plant body?An additional question is: Does leaching of BPA occur atambient temperatures in the environment (including fullsunshine)? As many food crops (vegetables and herbs)have been grown for decades already in a wide varietyof plastic containers it seems that if BPA were leachingand transported into the crops, traces of BPA wouldcommonly be found in the crops, as well as in thehumans who consume them. No such evidence exists
and no such link has been established. I am stillconcerned about how the general public seems to drawa connection between the potential presence of BPA inplants growing in plastic containers ("safe" and "unsafe"plastics), and the potential presence of BPA in drinks soldin plastic bottles.”Peter Knop · Ticonderoga Arboretum and BotanicalGardens“I am surprised that no one has mentioned theenormous amount of plastic used in row cropping andthe millions of tons of produce grown on such plastic. Ittotally dwarfs hydroponics or other container growncrops. Maybe the term "container" includes these, as forthe bottom of the raised beds the entire root system isexposed to this plastic mulch. This leads to anotherinteresting problem: some of these mulches arebiodegradable and their chemicals, like binders, becomepart of the soil. Aren’t they dangerous?”Willem Van Cotthem · University of Ghent“Indeed, heaps of plastic sheets are used in agri- andhorticulture, even biodegradable ones. If all thoseplastics, or only the "unsafe" ones, are leachingdangerous, toxic elements into the environment, we areprobably "doomed".Debi Sharma · Indian Institute of Horticultural Research“If leaching of BPA is higher at higher temperatures thenit is a matter of concern especially in tropicalconditions.”
Based on the responses I have received to the question Ihave put to ResearchGate, no clear proof has beenprovided that BPA or BPS is leaching into the soil inwhich plants are growing, or that BPA or other toxicsubstances are absorbed into those plants.Is it really dangerous to grow food crops in plasticcontainers?Let us have a look at a recent publication in ScienceDaily(2013/02):http://www.sciencedaily.com/releases/2013/02/130217084541.htmA scientific analysis of 150 studies in which humanbeings have been exposed to "low dosages of BPA"shows that "in the general population, peoples exposuremay be many times too low for BPA to effectively mimicestrogen 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 humanexposures, with the vast majority being at least 10 tothousands of times higher than what humans areexposed to daily. In addition, the range ofconcentrations spans from upwards of 10 grams perkilogram of weight per day down to 100 picograms per
kilogram of weight per day (a picogram is one millionthof a gram)."Unfortunately, the low dose moniker has been used bysome to promote the importance of selected toxicitystudies, for example, in arguments to ban BPA," saidTeeguarden. "For BPA and all chemicals, we need moreaccurate language to present these findings so thepublic and scientists in other disciplines can understandhow human exposures compare to exposures inlaboratory studies reporting toxicity."Although I am more convinced than ever that it is safeto grow plants in plastic containers, I would still like toobtain conclusive answers to the following twoquestions:(1) Is BPA (or BPS), within ambient environmentaltemperatures (even in sunshine), really leaching in anynotable concentrations from the plastic bottles, pots orbuckets in which we grow our fresh food?(2) If so, are plants absorbing it in such concentrationsthat 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 scientificstudies, I continue for now to promote my bottle towermethod (http://youtu.be/JtbOREs2kIo) as aparticularly effective way to combat malnutrition,hunger and poverty in developing countries.As long as all the specialists-experts of the worldscrutinize every day the production and sales of foodand drinks in plastic containers, as long as they allowmillions of people to eat and drink from plasticcontainers, I will continue to believe that the fresh foodwe produce in the same containers constitutes no directdanger for public health.