Plants will take up BPA from solution and metabolize it to B-glucoside.

Here is a link that might be useful: BPA plant study

Nice link. But if you follow this further after reading your link, you will find that many plant β-glucosides are carcinogenic to rats and humans and toxic to our liver. It seems that the hazard is only from eating (vs. touching, injecting, etc.) since the bacterial flora in our gut further digest man of the class of plant chemicals called β-glucosides. So the original question still stands.

Just because something doesn't have a recycle symbol or number on it, doesn't mean it is hazardous, although cheaper generally means less regulation. Check with the manufacturer online or find them from your retailer and call their customer service line and try to get more info. Usually they readily can give you the recycle code, although hazard info is more difficult to get since everyone who knows about it seems to have an axe to grind and you might as well be arguing about the greenhouse gases or politics before you can reach a consensus...

Good luck. Just keep in mind that recycle codes are not everything. Code 7 for example has everything from poisonous to approved for repeated food contact. HDPE is code 2 always, but what it is mixed with will determine its suitability for food contact. Even if someone says it is 'virgin' material, that doesn't mean anything if they use some hardener or UV stabilizer that is unsafe for food contact, so you can start in tyhe US by asking the manufacturer if it is FDA, USDA or NSF approved or certified and the manufacturer will know that since they pay about $5000 to get the certification. NSF 61 is lead and other dangerous chemical free, ok for potable water (so irrigation should be fine) but not necessarily for single or repeated food contact which is really FDA approved.

Good luck. Learning about plastics is something you can never do completely and all feelings of safety are really not dictated, conditions of use vary so much and there is still a lot that is unproven. It comes down once tyou weed out the obvious one to your risk aversion mentality. Personally, I think eating more veggies from a PVC hydroponic system is healthier than eating less veggies grown naturally in the Garden of Eden, but that is what you run up against. The best we can do is just buy FDA approved (usually PP and HDPE without regulated additives) and hope for the best. To give you an example I am making a similar choice for a possible home hydroponic system in the future with square PVC. Here's the problem: Go to a home improvement store and get a square PVC piece and you don't even know where it is made. My risk aversion says, no way. The reason is that most cheap stuff comes from China and so that is the centers majority of product and they probably couldn't trace a upplier if they tried they way they buy many of these commodities PVCs. So go on line and read, "Virgin Monolayer PVC" ... that must be better, right? They say it is better than the higher cheaper recycled content coextruded stuff, but if it isn't for food, who really knows since it hasn't been tested - what are the stabilizers going into the virgin PVC? So actually - they scared you that co-extruded was a problem, but I personally would prefer coextruded "virgin PVC substrate". Coextruded is cheaper because minimal additives go on the inside layer, the additives are what costs, and the outer shell has the recycles, etc, content with eg UV stabilizers etc additives. Well if you need stabilizers, but don't want additives overwhelmingly contacting the inside, co-extruded seem the way to go...

Well crap.

Ok how about this: Any ideas on a mfg for a "pretty much guaranteed safe" reservoir?

I'm just a Newbie, but after going to the Sterlite site they say all the products are BPA free, but still none of the totes are marketed or certified safe, so you can talk to people who are used to using them and say "I never gagged on my veggies" (and probably, they are pretty safe, but we are using them for something they were not manufactured to do, so the manufacturer really isn't too worried about answering our questions since he has bigger fish to fry where he is responsible.

Since you are going to be in the risk adverse crowd for medical reasons, I would in your place definitely buy a Rubbermaid model 3501 plus its cover (model 3502 or something like that) or similarly FDA compliant NSF certified HDPE (I wouldn't get a transparent polycarbonate one but that's opinion not factual, btw I'm a 'retired' chemist who worked in the plastics industry) tote used in the food service industry. It will cost a lot more than home depot and walmart but you can't buy peace of mind for $50 as easily and it'll make you feel you have a special system which is nice for a DIYer as long as they can afford it.

http://www.rubbermaidcommercial.com/rcp/products/detail.jsp?rcpNum=3501

You might have to paint it outside, others can give you that kind of advice better than me without practical experience doing this yet, so just be careful whatever you use to wrap or cover it doesn't defeat the food safe quality you paid so much to get. I know in plastics, PP (polypropylene) is commonly black in certified products for food contact, so maybe someone knows of a food-safe black PP tote, I haven't found one though.

Best luck!

This post was edited by PupillaCharites on Tue, Jun 18, 13 at 19:14

Way to unnecessarily scare foul_owl there pupilla. If a plant produces carcinogenic B-glucosides it won't matter if there is BPA in the water or not or if you grow it in the ground. Also, it is going to raise your lifetime risk of cancer from 50% to 50.000001% Because the plant metabolizes BPA, I wouldn't worry about it even if someone dumped a bottle of the stuff in the reservoir.

nil13, I'm sure you are responsible and I did not post to disagree with you, only to add to the discussion. Let's be honest, most of us think plastics are ok just because they are everywhere. I'll agree to that with the same thought that if I'm drafted to fight, the other guy will get the bullet.

Paying a $30 premium for the Rubbermaid 3501 in the big scheme of life for something FDA approved for and made for long term food storage I think is a viable option for whoever can afford it and is risk adverse. These cheap tubs are not made for hydroponics and it is Russian roulette; BPA is only one issue of many, and dismissing the risk as insignificant is irresponsible. Hairdryers and radiator hoses are not made for people to eat their food off either ... just because everyone is using cheap tubs for a use they are not intended doesn't guaranty safety, which is what the OP asked for and I provided a link to one.

There is not only one β-glucoside; metabolizing one toxin and turning it into others is not my idea of safe; plants produce β-glucosides at different rates, some plants are more poisonous than others and the rest of the discussion is better for a billion dollar toxicology study no one will finance, since there are dozens of β-glucosides and each has its exposure limits and each person may respond differently to toxins.

EDIT: If you want the 20 gallon Rubbermaid Commercial Brute gray tub with lid, that would be a more economical option, though not explicitly designed for foods and restaurants, the 20 gallon model is available, eg. from Amazon with free shipping for $28 and change. Both tub and lid are approved only by NSF for food contact under NSF Standard #2. That ought to be just fine for our use in the sense of a guaranty, but I have a question on that one regarding whether the molded lid gives any problems for setting net net pot holes. Generally though looks really well made and a good compromise to save about $30 on an economical DIY system.

This post was edited by PupillaCharites on Tue, Jun 18, 13 at 23:32

It seems this was discussed before and the little plastic recycling numbers indicate what is safe. If I remember correctly, 2 through 5 was okay. The others were not explicityly "not okay" just not explicitly described as okay.
Anyway just search this forum for something like reservoir and material. That will probably get you to the thread.

It would be more accurate to say 1-9 are not "not ok" and leave it at that...A common misconception, better just Google it for a more general view. The most common food safe resin is code 1; and a hydroponic example of either code 7 or 9 is Tower Garden that claims to be FDA food safe (which is quite possible if they have appropriate tests for their application). Code 6, polystyrene is used for planting pots and fast food....bottom line: from the site plasticmythbusters.org on recycling resin ID codes 1-9:

"Resin ID codes are not intended to provide guidance on the safe or appropriate use of any plastic item and should not be used for this purpose."

The reason this misconception has become so engrained is that people think of plastics as they do of metals, stainless is safe and copper is not (for plants).

The SPI, the Plastics Industry group has an educational video about recycle codes and says:

"[resin recycle codes]...do not indicate safe or intended use for a container; this is false and potentially harmful misinformation."

here's the video:
http://www.plasticsindustry.org/AboutPlastics/content.cfm?ItemNumber=823&navItemNumber=1125

Plastics is a different ball of wax. The recycle code only deals with the base resin and says nothing about the additives. Each machine has its own operators, formulations, temperature profile, etc... PVC for example is typically only 70% PVC resin and the other 30% is miscellaneous additives, some of which may not be appropriate if being used for an unintended use. To make plastics, the pure pellets are dumped into a stinky extruder with usually gigantic twin screws usually that force the resin melt through oven chambers to mix up with all the pure or whatever nasties, that possibly has run all kinds of toxic materials in prior runs. If they are not making food certified products, no one is concerned about what leachs out into food from this, or what was run before, or how much contamination is there as long as the product meets whatever spec they need... and on the contrary the key is to keep the maching running 24/7 with anything you can get an order and have a die to make, to be competitive since downtime will bankrupt the company, so no one will clean it with a micro scrubber unless it is part of the spec. In the case of injection molding, it is different process, but with the same risks.

Maybe it is my years working in R&D in a facility making PVDF right above the pilot plant, but after working in that place and seeing, smelling everything, the OSHA inspections and concerns, etc., I realized how complicated the safety issue is to pin down and would prefer just getting stuff from a facility that meets food spec. Sure, HDPE (#2) is a good bet, as is PP, but if you don't want to bet there are options

BTW PVDF (code 7) is the safest resin of all for a wide spectrum of food and safety, except way too expensive. I can only imagine what goes on in the economical production shops, especially cheap imported stuff without oversight.

This post was edited by PupillaCharites on Wed, Jun 19, 13 at 13:46

If those are your bullets Pupilla, they missed the mark. I am only talking about BPA. You can point out that there are other chemicals in plastics that could be dangerous and it is completely irrelevant to the discussion of whether or not BPA in hydroponic solution is a problem. BPA is approved for food contact so your suggestion to stick with food contact safe doesn't eliminate the chance of exposure. The specific point that I took issue with was the fearmongering tactic of referring to B-glucosides that are carcinogenic in a way that appeared to me to be inferring that BPA being metabolized into normal chemicals found in the plants presented a unique cancer risk. If the plant does not produce carcinogenic B-glucosides no amount of BPA is going to magically change that. Nevermind that the risk of cancer from carcinogenic B-glucosides is incredibly small.

Nils, I am also pissed about the 'fear-mongering' which I know as 'alarmism'. It is unscientific, and makes life particularly unpleasant to have a reasonable discussion. My only disagreement is that the article you linked to doesn't address the toxicology either way since increased BPA-derived metabolites or BPA itself, the overall concern is establishing toxic limits of the whole ball of wax.

I suspect on a personal level that BPA mongering really is a lot of ado for *me*. The problem is much more likely going to show that certain sensitive segments of the population are affected by it, and it will probably end up being pregnant women.

So, those were not bullets directed at you at all, because there is simply not enough real research done which determines non-toxic exposure limits of BPA or its specific metabolites in plants. To be more impartial about BPA, one needs to look at all sources of BPA and determine if the plastics in these hydroponic systems really contribute to a major portion of exposure. If you eat or drink much from cans, you are probably getting more straight BPA from them.

So, I am much less concerned about BPA than I am of generally non food grade plastics for our application.

So, pay $1000 for a commercial setup you can build for $150 with lower grade plastics, or consider the $250 option with all food grade plastics.

It is so hard for someone starting out to get an unbiased wiki on plastics.

I think that is a fair assessment. You're not getting BPA from leaching of plastic but the metabolites. And then you have to look at how much BPA actually even leaches. This would lead to infintesimal changes in the B-glucoside levels if any change at all. Compared to other BPA exposure vectors this one seems like a non-issue.