Polyvinyl chloride vs Polyethylene - Food Safety

[Jonathan Kadish NYC AA Chair]

I am just piecing out my system and by chance I wondered if PVC is food safe. Here is the information I found that will influence my choices:

 

Polyvinyl chloride (V or PVC)
Most cling-wrapped meats, cheeses, and other foods sold in delicatessens and groceries are wrapped in PVC.
BAD: To soften into its flexible form, manufacturers add “plasticizers” during production. Traces of these chemicals can leach out of PVC when in contact with foods. According to the National Institutes of Health, di-2-ethylhexyl phthalate (DEHP), commonly found in PVC, is a suspected human carcinogen.

Polyethylene terephthalate (PET or PETE)

Used to make soft drink, water, sports drink, ketchup, and salad dressing bottles, and peanut butter, pickle, jelly and jam jars.
GOOD: Not known to leach any chemicals that are suspected of causing cancer or disrupting hormones.

 

High density polyethylene (HDPE)
Milk, water, and juice bottles, yogurt and margarine tubs, cereal box liners, and grocery, trash, and retail bags.
GOOD: Not known to leach any chemicals that are suspected of causing cancer or disrupting hormones.

Read more: http://www.care2.com/greenliving/which-plastics-are-safe.html#ixzz1...

My question is if the white PVC tubing has those plasticizers?

[Jonathan Kadish NYC AA Chair]

Actually if you look at the product he is talking about, triple-layer PolyLaminate™, the outside layers are PVC and the inside is a Polyester mesh. From the little I've read polyester is fairly stable.

[RupertofOZ]

PET, while entirely re-cyclable which is a plus... isn't any where near as safe as HDPE...which is usually also UV stabilised...

 

And Todd.... I hope you used the "good" resins in your fibreglass tank.... because resins aint resins... and some of them are "bad"...

[Todd Sowell]

Yes, we made sure we had the correct resins

[Michael Clegg]

Jonathan,  Sylvia asked the same question, just yesterday.  As a systems designer, I am asked am quite often, PVC or not to PVC, that is the question.

Does PVC pipe leach chemicals? Is it toxic? 

Claims that it’s toxic have been refuted by the scientific community. The evidence shows it neither leaches toxic chemicals like lead, cadmium, BPA or plasticizers; release harmful organotins; pose major hazards in its manufacture, use and disposal; create a dangerous bio-film; nor form dioxins as water passes through, etc.

Moreover, it’s impossible for PVC pipe to leach plasticizers, BPA, lead or cadmium, since these aren’t even used in its manufacture nor are they part of its compound. 

www.charlottepipe.com  This company produces a type of PVC pipe that is often advertised as rated “Drinking Water.”  The following is further info.   ASTM – D – 1785, Drinking Water, CP-112P Ext. #1 or 00:27 Schedule 80

The possible answer might lie in the MSDS sheet. 

The Hazard Ingredients/Identity Information

Less than 3.2 parts per million (ppm) of residual chloride monomer (rvcm)

Standards for food contact applications

In January 1978 Directive 78/142/EEC set a limit of 1 mg VCM/kg for all materials and articles that are intended to come into contact with foodstuffs. The same directive states that vinyl chloride should not be detectable in foodstuffs by a specified test method, which has a detection limit of 0.01 mg/kg (10 ppb).

The typical upper limit for continuous use of PVC pipe is 140 F, but that is associated with working pressure. The Temp/Working Pressure can be confusing.

While induustry standards suggests its use should be with cold water only, yet there are no references as to what temp is the threshold of cold water at low pressure. While PVC can handle temps as high as 180 F (82.2 C) at pressures up to 100 PSI. Some documents suggest temps no greater than 140 F (60.0 C) 

The best answer that I have ever received from people in the industry – 73 F (22.7 C), yet, I find this number to be possibly inaccurate, I feel comfortable with water that hovers in the mid-80's.

There are other types, such as PPR-Aluminum-Plactic stabi pipe for drinking water, for hot-cold applications. Do date, I have no experience with it.. I have been advised that it remains quite expensive.

The smooth surface of the PVC pipe is also resistant to bacterial contamination, such as E. coli. Therefore, many water companies rely on PVC pipe in their systems in order to keep them free of contamination. 

Since Tilapia best reside with 25-30 C (77-86 F), the use of PVC should be considered safe.

Any water temps above that, one might consider the use of a chiller to bring the temp down.

Let us remember that with higher temps, you will realize higher O₂ demands.

I have never seen any issue made or addressed as the PVC within Howard M. Resh's work, Hydroponic Food Production, nothing negative within any of the literature of Dr. Timothy Fitzsimmons of the U of A, nor within the many publications of Dr. James Rakocy. 

[TCLynx]

Here is a blog post I wrote on the subject of plastics and aquaponics materials just the other day.

Don’t let panic over plastic stop you from getting started.