Email communication between Dryden Aqua & PWTAG ( Pool Water Treatment Advisory Group)

General email from Dryden Aqua to swimming pool industry

Asthma in swimming pools and spas

There has been a great deal of information in the trade press and television recently about swimming pools and the problem associate with trichloramines acting as a precursor for asthma. Certainly if you go into a swimming pool and your eyes sting from the trichloramine, it also means that there is damage being done to your lungs, the difference is that you don’t feel your lungs sting.

Duty of Care

The swimming pool and spa industry has a Duty of Care for their clients. If you know that you are causing health issues then you should be taking action to resolve the problem. The public and pool staff  are becoming more aware of the health implications of swimming and working in these environments, it is only a matter of time before there are litigation cases against swimming pool operators that are not practicing a “Duty of Care”. It is unfortunate that we have these problems because swimming is one of the best exercise activities for health and fitness.

Over the last 10 years there has been a huge amount of research concentrating on the health effects of trichloramines and trihalomethanes THM`s, and as a consequence the maximum permissible THM level has been reduced in several European Countries. Germany is one notable example with a limit of 10ppb, in the UK the limit is 100ppb however the maximum concentration is not enforced. Indeed the trichloramine levels are very rarely even monitored.

I consider the parallel with trichloramines & THM`s to be almost similar the series of events that took place with asbestos. We have known about the problem for decades but nothing was actually done for around 40 years, in the intervening time the public suffered.

The research to date has centered on the public health effects of trichloramine, but very little has been accomplished in finding out how trichloramines are produced in swimming pools. It is only once you know the mechanism that you can actually do something about solving the problem. This seems a logical first step, but it is a first step that has never been taken. Dryden Aqua has recently completed a 3 year research project funded by the European Commission under the Life Environment initiative. The research concentrated on water filtration, but as opposed to focusing on a narrow field, the research was expanded to encompass not only the physical effects of filtration but also the chemical and biological interactions. It was discovered that trichloramines are produced by a reaction between ammonium and chlorine in the thin bacteria film called the biofilm that coats every surface in contact with the water.

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Reply from PWTAG dated 26th March 2007

Dear Dryden Aqua


On behalf of the Pool Water Treatment Advisory Group, I would like to challenge a letter sent out by you recently (copy below). I don't know
how widely this was distributed; indeed, I would be grateful if you could let me know this.

1 In the first paragraph there is the statement that trichloramine causes 'damage' to lungs. Although we are well aware of the research findings of
Professor Bernard and others, we are not aware of any conclusive proof that this general statement is justified. Can you provide any such evidence?
 
2 In the third paragraph on page 1 maximum permissible trichloramine levels are stated. We are not aware of any such levels and it would appear that the levels stated have been mixed up with the levels for trihalomethanes.

3 The last paragraph on page 1 refers to a report which would appear to contain the fundamental logic behind some of the statements made in this
paper. Can I ask for a copy of this research paper so that we can review the
claims.

4 In the second paragraph on page 2 it is stated that the sand in filters is 'the source' of trichloramine (the next paragraph undermines that, but only
slightly). Can you substantiate this statement?
 
5 The report fails to acknowledge that there are many hundreds of pools around the world which operate very satisfactorily with sand filters, with
very low levels of trichloramine in the atmosphere.

I look forward to your response

Regards

Brian Guthrie
Secretary

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From Dryden Aqua  26th March 2007

Dear Mr Guthrie,

Many thanks for your email I welcome open discussion of the topics.  I have  attached to this e.mail a copy of two papers which give back-ground
technical information, on how AFM works and the mechanism for trichloramine  production. I have already presented the information at an ISRM conference,  and the papers have been published in the trade press.  The research  was  partially funded by the European Commission in association with several  water companies in the UK.  Our initial focus was on the treatment of  drinking water,  the removal of oocysts and reduction of THM`s with the  objective to improve drinking water quality, public and environmental
health.

Similar issues exist with the swimming pool industry, however because of the  much faster flowrates through the sand filters, higher water temperatures,  exponential bacterial growth rates, high nutrient loads etc etc,   the  problems are all amplified.   You may be interested to know that I did my  PhD on the use of zeolite filter media and sand filter design so I know a  bit about the subject.  Sand filters when sized and operated properly will  give good water quality, however like any product,   improvements can always  be made.

In reply to your questions, as a biologists involved with ecotoxicology,  I  can categorically say that trichloramines are extremely toxic and dangerous
chemicals at low concentrations, you just have to look at the published  48hr LC50 data to confirm this point.  However it is going to take many
years to determine precisely how dangerous the chemicals are, and if there  is a safe or acceptable exposure limit to people and children of different  ages, health status,  ethnic groups, and to the development of the foetus.  We are dealing with some serious issues , but we will  probably never have
the complete answer.

I am afraid that I cant accept a wait and see attitude when it comes to the  health of children,  we know that there is a problem, how serious a problem
is still to be quantified.  If there is an opportunity or a strategy that  can improve water & air quality and reduce risk then it should be given
consideration.  The alternative is chlorine free products which will  eventually be developed, however for the time being;  copper,  catalytic and
enzyme based products are dangerous and  represent to great a risk for  horizontal disease transmission.

In the meantime I await your comments regarding the attached papers.

regards

Dr. Howard T Dryden
Dryden Aqua

reports 

1. Trichloramine and Asthma in swimming pools,  problem solved download

2.  filters, 30% increase in performance, remove Cryptosporidium and Giardia oocysts. Download

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From PWTAG  5th April 2007

Dear Dr Dryden

Thanks you for this material, some of which I know we have seen before. Incidentally, you did not respond to my question about the distribution of that letter we challenged.

I have had two responses from within PWTAG to your reply. I will append them here, largely un-digested. Perhaps you will let me have a further response.

Regards

Brian Guthrie

APPENDIX

1
On the chlorine chemistry: where he states that trichloramine nitrogen trichloride for the past 50 years - cannot form at pH values
above neutral. His whole hypothesis rests on this as he claims the only low pH is in the bacteria surrounds. But NCl3 can form at higher pH values when the ratio of free chlorine to ammonias high. Therefore his theory is inconclusive at best.
Andy
 
2
What evidence is there whatsoever that biofilms have a low pH and it is their presence that causes nitrogen trichloride?  Every scientific or
technical paper I have ever seen says that nitrogen trichloride is formed in the pool when chlorine meets with ammonia from sweat, skin, urea etc. I
simply cannot accept that it is the biofilm that forms on surfaces and can protect bacteria that causes nitrogen trichloride as Dryden seems to be
saying, in the presence of free chlorine at the levels we recommend bacteria is killed in fractions of a second so how come our filters are so polluted?
I dont know anything about biofilms but accept that they exist on any surface, but so what, surely most are completely harmless and even those
that form to protect bacteria cannot contribute to a lowering of pH in the water as Dryden implies and once again if the bacteria are so protected the
minute they are exposed to chlorine they are killed. Neither can I accept that periodically the filters become unstable and high levels of bacteria
are discharged into the pool making it cloudy and this can happen every few weeks, not in any pools that I have managed it hasn't. I do accept that a
filter without disinfection can create an excellent substrata for bacteria and act as a biological filter, this was a common practice years ago but it did cause problems if there was not sufficient chlorine in the water to deal with any bacteria that were then washed into the pool. Today we have what is
virtually a constant level of free chlorine maintained throughout the pool system, and this will surely prevent the filter acting as a biological
filter. The question we also have to ask is that if what Dryden says is true how can pools in Germany, Austria and a the best pools that we have operate with such low levels of combined chlorine, don't their filters get biofilms

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E.Mail sent to PWTAG 5th April 2007

Dear Brian,

Thank you for your e.mail,  in response to the two questions in the Appendix
I reply as follows;

1. Production of trichloramines at a pH of less than 5, information was  taken from the German DIN standards 19643.  The reaction is of course an
equilibrium relationship however above a pH of 5 the percentage production  is extremely low.  I do not understand how my statement can be considered inconclusive when it is in virtually every technical paper and text book  relating to trichloramines ?

2. I am actually disturbed by the statements given in Appendix 2, I  appreciate that you have not reviewed the statements presented by your PWTAG
members, however as an official response from PWTAG it is a bit  embarrassing.

    a. In a 25m pool there will be in the order of 10 tonnes of sand, 30,000  square meters of sand surface area and a biofilm on virtually every grain of
sand.  It is basic biology that the pH in the biofilm is acidic, it is  therefore absolutely a major source of trichloramine production. Also the  biofilm is the location where mineralization of protein and urea occurs,  it  is therefore the principle source of ammonia production.
    b. Human skin is acid, so trichloramines will be formed on skin, or on  any surface that is acidic, the text books failed to consider the sand as  a
source of trichloramines,  because the authors simply did not know.
    c. Chlorine will kill most bacteria in the water column within a few  seconds. However it is also a fundamental biological parameter that the
biofilm will tolerate the chlorine levels used in swimming pools. I refer  you to the following paper; International Journal of Hygiene and  Environmental Health    February 2001, vol. 204, no. 2,   pp. 139-142(4) .  The statement by your PWTAG member that chlorine will kill bacteria in the  biofilm is contradictory and flawed on so many levels that I can not  realistically respond to the rest of the comments.

3. Further comments.

At Dryden Aqua we have been conducting research for the European Commission  for the last three years on media bed filtration and water quality.  As a  company our personnel did PhD`s on the subject, and this is the area in  which we have been working for the last 20 years.  We have taken the
technology beyond any technical paper recently published. We have many  swimming pools in which we have proved in practise that it works over the
last 5 years.

We can not ignore the health implications of trichloramines and the research  funded by the European Commission, even although it is not conclusive.  I  believe there is sufficient circumstantial evidence to support the case that  trichloramines cause lung damage. We see parallels with cigarette smoking,  and asbestos when the data was ignored for many years before any serious  action was taken. When it comes to the health of children I do not think we  can afford to take risks and given that we have a solution to the problem,  we are in a position to make a difference and show the rest of Europe.

I would be pleased to support PWTAG and welcome your support and comments.

best regards

Howard Dryden
Dryden Aqua Ltd
Edinburgh.

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email sent to PWTAG 14th May

Dear Mr. Guthrie,

Following on from our recent e.mail communications ( 5th April)  regarding our work with  AFM and NoPhos for the control of water quality in swimming pools,  please  let me know if there will be any further comments from the PWTAG committee.

I can assure you that we have basically eliminated trichloramine production  while still using chlorine , and at the same time we have kept in compliance
with German DIN standards.

I confess I was disappointed by the negative response from your PWTAG  committee members,   I had hoped for a more constructive criticism.  However  the door is open so if you wish to discuss any points or visit a swimming  pool, please let me know.

Howard Dryden


Dr.Howard T Dryden
Dryden Aqua Ltd
Butlerfield, Bonnyrigg
Edinburgh EH19 3J

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No further response from PWTAG has been received despite several emails being sent requesting a reply