BPA and Use of PVC in Aquaponic Systems

[Mark Andrews]

I am new to aquaponics and in the very early stages of my education. In many of the videos I have viewed and in reading on plumbing for systems, it appears that the use of PVC is fairly common. Does anyone have knowledge / information on BPA leaching from the PVC into aquaponic systems and ultimately into the produce and fish? 

I have found some information at the following link to Healthstuff.org in their 2012 Garden Products Study: http://www.healthystuff.org/findings.050312.garden.php, retrieved 1/4/2014.

Thanks in advance for your reply.

[Vlad Jovanovic]

I doubt you'll find any such info as it relates to AP specifically...But you can avoid BPA (and other potential phthalate issues) by using only rigid u-PVC. Remember, BPA and other phthalates (plasicizers) are used to make PVC soft and pliable. Unmodified, rigid PVC contains no such plasticizers. 

As far as soft, pliable vinyl goes, no covalent bond exists between the vinyl and its plasticizer...so chemically, the bond is a weak one...which results in leaching over time. So, it probably would not be advisable to use in any recirculating, soil-less food production system. If you need a pliable hose there are other options out there besides vinyl.

[Alex Veidel]

I knew you would have a word of wisdom for this subject ;)

Vlad Jovanovic said:

I doubt you'll find any such info as it relates to AP specifically...But you can avoid BPA (and other potential phthalate issues) by using only rigid u-PVC. Remember, BPA and other phthalates (plasicizers) are used to make PVC soft and pliable. Unmodified, rigid PVC contains no such plasticizers. 

As far as soft, pliable vinyl goes, no covalent bond exists between the vinyl and its plasticizer...so chemically, the bond is a weak one...which results in leaching over time. So, it probably would not be advisable to use in any recirculating, soil-less food production system. If you need a pliable hose there are other options out there besides vinyl.

[Mark Andrews]

thank you for your reply.

[Carey Ma]

Hi Vlad, long time no talk.

I concur. PVC is probably not our best choice (as if we had many) but from what I understand, the degradation is mostly on the outside surface which is exposed to the sun so leaching into the system would be less. This doesn't mean there isn't any or that it is safe. I think "panda" (white on the outside and black inside) HDPE would be a better choice but until there are enough of us to demand it from manufacturers I guess we don't have much choice.

Cheers

[Jim Fisk]

Personally I think the health benefits of AP so far outweigh the negs of pvc that I would not even think twice. Just get your system designed for your particular needs and get growing. Don't get hung up in the weeds

[Vlad Jovanovic]

The only issues I can think of surrounding rigid u-PVC are environmental ones which are rooted in it's manufacturing process. Again, if you need flexible hose there are many other options.

@Carey...yeah, it's sure been a while :)

Certainly HDPE is a superior material...but man is it pricey! Guess there is a reason why PVC is referred to as "the poor man's plastic. If we're talking about degradation of pliable PVC (not the rigid piping)...yeah the outer surfaces exposed to the Suns UV rays seem to suffer most, but studies have show (again we're talking PLIABLE PVC here) that certain minerals like calcium in the water exacerbate degradation and leaching...so it's not always just UV exposed surfaces (again this has nt been shown to be a problem with unmodified rigid PVC).

[Nathan Kaufman]

Great info, thanks Vlad!

While on the subject... Any thoughts on Polypropylene (PPL) containers for media beds or tanks? From what I've seen it's one of the most toxic plastics to produce, but once hardened it's one of the most stable in terms of UV and biological degradation. I've used PPL tubs from ikea for several small scale home projects and found them quite useful. 

[Vlad Jovanovic]

Hey Nate...I don't know if PP is 'one of the most toxic plastics to produce' or not, since none of them (plastics) are exactly 'fun' for the environment...but even in the case of PP production, it seems like the largest concerns once again regard additives (in the case of PP mostly antioxidents like BHT and BHA) that are produced and added to the PP plastic. And even those concerns are of an academic nature for now. Basically, the antioxidants behave unpredictably in the presence of talc (which is used in quite judiciously the manufacturing process of many plastics) beyond a certain temperature threshold. They then form new low weight molecular chemicals which some believe could lead to to faster migration out of the plastic (I guess what we'd call leaching).

So issues surrounding toxicities need to be further explored, and I don't know that they have been. There's just not much money in proving that items used commonly in the household, in medicine, in industries of all sorts, can be toxic. That type of work is usually poorly funded (if at all) and spans years or decades.

Once again its the additives in PP that suck, and not the PP plastic itself (just as in the case with pliable PVC). BHT and BHA have been shown to cause tumors, mutations and whacky effects on the endocrine systems of animals tested (and much like BPA, fall into a particularly nasty category of toxins called "hormone disrupters".

BUT... if its any 'consolation' BHT and BHA are commonly used as antioxidants in FOOD, cosmetics and pharmaceuticals! ...and not just PP plastics.  

[Averan]

Makes my food more flexible too. ;)

[Alex Veidel]

Vlad, what are some of the other options for flexible vinyl tubing? I recently realized that I have a tiny piece (1 ft. long)  in my system :P

The extra plasticizers in my diet have increased my intelligence by making my brain more flexible, so it's been really easy to wrap my mind around things lately, but it keeps wanting to flow out my left ear.....

Vlad Jovanovic said:

I doubt you'll find any such info as it relates to AP specifically...But you can avoid BPA (and other potential phthalate issues) by using only rigid u-PVC. Remember, BPA and other phthalates (plasicizers) are used to make PVC soft and pliable. Unmodified, rigid PVC contains no such plasticizers. 

As far as soft, pliable vinyl goes, no covalent bond exists between the vinyl and its plasticizer...so chemically, the bond is a weak one...which results in leaching over time. So, it probably would not be advisable to use in any recirculating, soil-less food production system. If you need a pliable hose there are other options out there besides vinyl.

[Jim Fisk]

Hey Alex, you had me reaching for the "Like" button but alas I couldn't find one

[Vlad Jovanovic]

Good one Alex...you can always use PP tubing (polypropylene)...