Toxicity of HEDP?

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smallpooldad

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Aug 6, 2008
429
Honolulu
I am sorry that I have to ask a further question of chem geek but I think he maybe is one of the few persons on this forum that may be able to distill an answer from this technical paper on:

"Human & Environmental Risk Assessment on ingredients of
European household cleaning products
Phosphonates"

Located here:

http://www.heraproject.com/files/30-F-04- HERA Phosphonates Full web wd.pdf

It discusses the toxicity of HEDP and is way beyond my understanding.

Any others of you that feel up to the task please chime in.

The reason for asking this question is that I plan to up the maintenance sequestrant level to 60 or 70 ppm, as measured by Jack's Sequestrant Test Kit, maybe even higher if it is safe enough, using Jack's Magic Purple Stuff, an HEDP sequestrant, to control iron staining. I am trying to find out at what level using Jack's Purple Stuff it might be too high, and therefore unsafe. The "Purple Stuff does add phosphates to the pool. I think and hope the answer can be found in this paper.

Jack's Magic Purple Stuff MSDS (Material Data Safety Sheet) is here:

http://www.jacksmagic.com/pdfs/MSDS-JMPURPLE.pdf

This link speculates it contains 20% HEDP:

http://www.poolforum.com/pf2/archive/index.php/t-16271.html?s=d600d7b329104a62181658ffc584b29d

Thank you to those that might help.
 
You don't have anything to worry about. HEDP is of low to moderate oral toxicity with a wide range of 581 go over 5000 mg HEDP per kilogram of body weight. At 50 mg/L, this means drinking at least 10 liters of pool water and possibly as much as 100. The dermal toxicity is low so not even worth considering. It is at most mildly irritating to skin, but only when concentrated (i.e. not diluted in pool water). The chronic (repeated dose) toxicity is low at > 1500 mg/kg. HEDP is not mutagenic, genotoxic nor carcinogenic. The No Adverse Effect Limit (NOAEL) for HEDP is set at 19 mg/kg/day so you'd have to drink 400 ml per day of 50 ppm HEDP pool water and you'd still show no adverse effects.

The bottom line conclusion was that HEDP and other phosphonates were safe for consumer use in household laundry and cleaning detergents and these are far more concentrated than their use in pool water.
 
chem geek,

Thank you for the information.

Called Jacks's Magic, at 1-800-348-1656, and they stated it takes 1.5 oz to raise the sequestrant 1 ppm for the Pink stuff, the Blue stuff, and the Purple stuff. The person I spoke with could not tell me if this was based on a 100% HEDP or 20% HEDP reading, therefore at say 100 ppm on the test kit would I be measuring 20 ppm (at 20%) or 100 ppm (at 100%)?

You wrote that the No Adverse Effect Limit (NOAEL), "and you'd still show no adverse effects" for 50 ppm 100% HEDP is set at drinking 400 ml (13.5 fluid ounces). If Jack's Magic Purple Stuff is 20% HEDP might then the amount one would need drink would be 2,000 ml (67.5 fluid ounces per day - a 3.5 fluid ounces over 2 quarts = about 8.5 cups). Quite a bit of pool water especially if one has a saltwater pool.

I did increase the Purple's level to 70 ppm, testing with Jack's Magic Sequestrant Test Kit, this might represent a true 100% HEDP level of 14 ppm (as the Purple Stuff only contains 20% HEDP), well below the daily "NOAEL" level of 50 ppm you mentioned or it might be a true 70 ppm, I am not sure.

I will see if this level stops re-staining and advise at a later date. I might go as high as 100 ppm on the test kit if it does not solve my re-staining issues which might represent a true 100% HEDP of 20 ppm, or would it be 100 ppm?.

On the quart bottle is does state one can go to 2 bottles for troubled pools which would be a dosage of 42.7 ppm, but is it 100% or 20% of that figure?

I hope I got this right, please correct me if not and what are your thoughts on the true level of the ppm of the sequestrant. Additionally nowhere on the bottle does it talk about pH, could one allow the pH to rise to between 7.4 and 7.6, say 7.5, without metals falling out of solution? On this forum keeping the pH at 7.4 or slightly below but no lower than 7.2 seems to have always been the recommendation to keep metals in solution.

My concerns if indeed the sequestrant level is a measured at 100% might have issues. Pool owners that have dogs that drink daily from the pool might have a problem even at 50 ppm or possibly at 42.7 ppm, my new dog will not go anywhere near the pool after falling into once and never drinks from it. Young children especially in non-salt water pools might have a problem if they swim daily and possibly drink from it daily. My own grandchildren come over rarely to swim in our pool so I do not see that as an issue and do not as far as I can see drink from it. Babies in such a pool would not be a good idea. What are your thoughts on this?

Also found this article I do not know if it might be of help:

http://www.surechem.org/index.php?A...tab=desc&lang=EN&db_query=2:0:&markupType=all

Thank you.
 
Update to prior post.

chem geek,

Just found this paper:

http://pmep.cce.cornell.edu/profiles/miscpesticides/misc_E_N/hedp/hedp_exm_0598.html


So it seems from these paragraphs that is not as bad as I thought. Beagle dogs from an EPA study, reached a NOEL at 3,000 ppm, and the Lowest Observed Effect
Level (LOEL) was 10,000 ppm, with HEDP. So it seems that 100 ppm is not really and issue even for a little beagle.

Am I understanding this correctly?

Thank you.
 
The mg/kg and mg/kg/day are talking about milligrams of pure HEDP. We were only talking about the effects of HEDP when diluted in pool water to around 50 mg/L (ppm). Obviously, if you were to drink concentrated HEDP in a product, then that's toxic.

As for the chronic effects tests on dogs, the ppm is not relevant since it depends on how much they eat or drink. What is relevant is that the No Observed Effect Level (NOEL) was 75 mg/kg/day and the Lowest Observed Effect Level (LOEL) was 250 mg/kg/day. If one has a 10 kg (22 pound) dog drinking 2 liters (about 2 quarts) of 50 ppm HEDP pool water every day, then that translates to (50 mg/L ) * (2 liters/day) / (10 kg) = 10 mg/kg/day so less than the NOEL level. So yes, you don't need to worry about the HEDP with respect to dogs. Note that these limits are higher for dogs than for the rats in the other study (NOEL of 75 mg/kg/day vs. NOAEL of 19 mg/kg/day).

Borates are more toxic to dogs since the No Observed Adverse Effect Level (NOAEL) was 8.8 mg/kg/day and the LOEL was 29 mg/kg/day. So relatively speaking, HEDP is 8-9 times safer in terms of the weight quantity needed before adverse effects are seen, at least for dogs.
 
chem geek,

Thank your for the reply.

It was good to read that is relatively safe even for a small dog, and by extension even for small children, babies I personally prefer not to swim in pools but that is a personal choice, others may disagree, plus we have no babies in the family at present.

As stated before I will advise on the re-staining results at the higher levels of sequestrant, in 3 to 4 months.

In reference to my question in my prior post any thoughts on allowing a higher pH, say 7.5, with higher levels of sequestrant?

Thank you.
 
A higher pH risks more metal staining but a higher metal sequestrant concentration lowers such risk so they should somewhat balance each other out. If you make the changes slowly, then you can figure out if the approach is working since you can see if staining returns.
 
chem geek,

Thank your for the reply.

Apologies for being a little late with response.

Was busy the last few days and still have not fixed the automatic acid feeder so pH moved to 7.5 and a few extremely faint iron streaks started to appear, lowered it to 7.3 and they have nearly disappeared. Sequestrant level is at around 100 ppm, this seems to do the trick in my pool at present, basically I think the sequestrated iron load is quite high as it has been more than a year and possibly a year and a half since I drained the pool.

Next time sadly I may need to drain the pool otherwise as iron continues to be blown into the pool. At some point I might have to raise the sequestrant level to 150 ppm, which I think is too high.

One interesting think to note is that the sequestrant seems to have a sanitizing effect, the SWG chlorine production at 24% setting gave around 5 to 6 ppm chlorine depending on the day and the chlorine had risen to 8 ppm maybe this is why the pH changed quickly, now at an 18% it gives the same 5 to 6 ppm chlorine. Also the pool looks super clear at 100 ppm, at 50 ppm it looked very clear. It is a noticeable difference, however small, why I do not know. . I think I may drop the run time on the pump from 5 hours to 4 hours, and up the SWG chlorine production to 22%, this will then save 6.6 amps per hour at 220 volts or about $15 per month in electricity charges at our .35 cents to .36 cents a kwh. Enough at least to pay for sequestrant replenishment.

Thank you.
 
What would 50mg of 100% HEDP per litre equate to in ppm?

Quick question.

What would 50mg of 100% HEDP per litre equate to in ppm of sequestrant in a 10,000 gallon pool.

The reason for the question is that a number of chemical companies state that when acting as a sequestrant the range should be a minimum of 10 mg, and the recommended maximum being 50 mg.

Thank you.
 
Jack's Magic "The Blue Stuff" has a density of 1.19 while "The Purple Stuff" has a density of 1.09-1.19. Only "The Magenta Stuff" has a density of 1.45 which is consistent with a 60% HEDP solution. When they say in their MSDS "Proprietary Formulation 100% (Contains 1-Hydroxyethylidene-1, 1-diphosphonic Acid)", this does NOT mean this is 100% HEDP and in fact I don't think you can get 100% HEDP. It's mostly sold as 60% HEDP in a water-based solution. Why don't you ask Jack's Magic about this difference in the MSDS "Specific Gravity" and how it relates to the concentration of HEDP in each product?

If I use The Pink Stuff at 60% HEDP concentration, then their recommended dosing of 1 quart (0.946353 liters) in 10,000 gallons (37854 liters) would be (0.946353 L)*(1.45 g/ml)*(1000 ml/L)*(1000 mg/g)/37854 = 36 mg/L (ppm).

The other two Jack's products I mentioned, if I assume (0.19/0.45)*60% = 25% concentration, would be (25/60)*36 = 15 ppm.
 

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Chem Geek,

Spoke with Jack's Magic, the stated that 1 1/2 ounces of the Pink and the Purple both raise the ppm by 1 ppm. I mentioned the fact that the Pink contains 60% HEDP and the Purple 20% but they said it makes no difference to the way it raises the ppm. I found this odd and I told them so. They stated the formulas are proprietary and that they will not disclose any further information. I could not get them to tell me how many ppms there are the Purple Stuff based on a 50mg per litre of a 60% solution.

It might be that you can talk to Jack himself, I did not talk to him. He might help you as you both speak the same language.

Thank you for your help.
 
chem geek,

Thank you once again for the reply. It does seem to work but I think that so long as I have no re-deposit of iron issues I might let the Purple Stuff sequestrant settle for maintenance at around the 40 - 42 ppm mark, or two 32 oz bottles for 10,000 gallons. Even they state 2 bottles is OK.

For what it is worth, one interesting note is that when I spoke with the Jack's Magic representative he was very interested in the fact that Hydrogen Peroxide was used as an oxidizer. He made the comment that HP is really a very strong oxidizer, he did this in a pleasant way, not disagreeing with its usage.

Thank you.
 
Hydrogen peroxide is both an oxidizer and a reducing agent depending on what chemical species are around to react with. So in the presence of iron, it is both since it can reduce ferric iron found in ferric oxides (i.e. rust) to ferrous ion and then it can oxidize it back into ferric ion again which in your case might have precipitated it if it wasn't bound up by sequestrant first. I wouldn't call hydrogen peroxide a "very strong oxidizer". It's a strong oxidizer in the same way that chlorine is a strong oxidizer and they are both somewhat selective in what they oxidize.

Even though the standard reduction potential of hydrogen peroxide is higher than that of chlorine, the very strong oxidizer of potassium permanganate has a lower reduction potential than hydrogen peroxide, but potassium permanganate is not nearly as selective in what it oxidizes compared to chlorine and hydrogen peroxide. So you can't solely go by a thermodynamic standard reduction potential -- it just says what is possible, not what actually happens. According to the laws of thermodynamics, our bodies should get oxidized by oxygen in the air and essentially burn up (react without flame), but this doesn't happen or effectively happens very, very slowly at room temperature because the reaction rate is limited by the high activation energy required for the reaction.

Even a strong oxidizer such as ozone doesn't react much with ammonia while chlorine reacts very quickly with ammonia. One really can't make generalizations and needs to be more specific about what exactly is getting oxidized. At the levels of hydrogen peroxide you were using, I would not characterize it as being problematic in any way. Just consider that 3% hydrogen peroxide, which is 30,000 ppm, used to be used in the household for wounds until finally people started realizing that it was damaging to skin, but you were using far lower concentrations in the pool water.
 
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