Plasticizer test

[lean mean &green]

i recall several threads where this too-little-too-late test was absolutely killed.

not a shred of news other than another lab is wasting resources on this limited use (if not downright useless) test.

huh? i must have missed those threads.

the OP asked a few honest questions and a couple of helpful people tried to provide honest answers. the DEHP test will have limited effectiveness like pretty much every other anti-doping intervention. agenda much?

 

[JA.Tri]

Mambo95 Lean,Mean&Green

I like to believe that the sentiments that you both express: are true/will reach fruition.

python may be correct, however I prefer to think of the plasticizer test as a small but integral part of the anti-doping strategy.

 

[python]

<snip>the DEHP test will have limited effectiveness like pretty much every other anti-doping intervention. agenda much?

this statement alone equating a practically useless test to the number of very successful anti-doping measures shows who has an agenda or more likely limited understanding testing.

 

[lean mean &green]

this statement alone equating a practically useless test to the number of very successful anti-doping measures shows who has an agenda or more likely limited understanding testing.

an obvious strawman. i simply stated it's usefulness is limited. there is no perfect test and all analytical methods have limitations - no one said they were all equally effective or limited.

 

[python]

an obvious strawman. i simply stated it's usefulness is limited. there is no perfect test and all analytical methods have limitations - no one said they were all equally effective or limited.

you are unsuccessfully looking for a back door after your own strawman. you tried to turn an obvious objective fact into a personal agenda. using sloppy language when speaking of a scientific test was on you.


again, as many have stated and seem to have accepted, this test is too little too late going forward.

 

[lean mean &green]

you are unsuccessfully looking for a back door after your own strawman. you tried to turn an obvious objective fact into a personal agenda. using sloppy language when speaking of a scientific test was on you.


again, as many have stated and seem to have accepted, this test is too little too late going forward.

i know this game, how about - i know you are but what am i?

 

[python]

i know this game, how about - i know you are but what am i?

this thread is about a plasticizer test.

so i could care less who you are.

 

[Special_oz_ed]

G'day Merckx index,

I'd spent a fair bit of time constructing a reply, but for some reason the Forum logged me off.

You ask,

Can you provide a source for this statement

First, did you read the link I provided? It cites Japanese exposure of 2mg per day of DEHP (IV bags are in that order - 3mg and up).

Second, Segura et al's study in Transfusion 50 (1) states,

The appearance of some outliers among athletes (Subjects A, B, C, and D in Table 2) may indicate either a particularly higher environmental exposure than usual or a sudden excretion as a consequence of blood transfusion processes.

So, Segura et al even allow for 'higher environmental exposure'. Had more for you, but I'm not going to trace all the articles all over again.

A lot more work needs to go into the methodology of the plasticiser test before it will be robust enough to be a suitable WADA test.

 

[Señor_Contador]

Yes, because ultimately there's a limit to what science can achieve. The idea that scientists will always be way ahead of the rest of the world is false. Frequently they shrug their shoulders and say 'this is the best we can do'.

You guys are not getting it...

Doping will always be ahead.

And if the learning curve flattens out some time in the future, I can honestly see all these cyclists and team bosses hiring a slew of big time lawyers that can pretty much turn the current anti-doping laws into nothing more than empty words.

And the thing is that even though some countries spend millions in fighting doping, while it's the small lab in the middle of the Sierra (in California) or the riders who decide to create a cladestine lab with the help of Guru X, that seem to evade controls 99% of the time. Imagine what would happen if they were dealing with a trully advanced doping programme, the kind carried out in the RDA? None of the riders will test positive.

Then what?

 

[Señor_Contador]

haha, on a longer timeline there's much much more money to be made by advertisers, equipment manufacturers, leagues, and team owners by establishing the credibility of sporting results through effective anti-doping.[...]

Yes, the very same companies that have their crap built by some dark-skinned teenager in the middle of south east Asia for $ 5.00 and then sell their crap in the US or Europe for $ 500.00. Yeah, that group.



The very same group that will forgo profits as long as cycling is "clean".



I swear to God, some of you have the strangest theories I've heard anywhere.

You couldn't sell crack to a crack addict even if you gave it to him.

 

[JA.Tri]

doping leads by a decreasing margin

I agree with the view that by the very nature of the beast anti-doping measures will (at least to a very large extent) be reactive.

However measures akin to the Bio-Passport will provide a "funnel" that increasingly proscribes the range of doping. That is, B-P (or similar) will only allow limited doping. And over time the mouth of that funnel will (IMO) decrease in diameter.

 

[Señor_Contador]

I agree with the view that by the very nature of the beast anti-doping measures will (at least to a very large extent) be reactive.

However measures akin to the Bio-Passport will provide a "funnel" that increasingly proscribes the range of doping. That is, B-P (or similar) will only allow limited doping. And over time the mouth of that funnel will (IMO) decrease in diameter.

Right, to the point that the powers-that-be have a system so fine-tuned that, although it's not 100% certain, it will deter people from doping and hence doping will be a problem of the past.

If that's what you want to believe... errrrr, be my guest.

 

[JA.Tri]

Right, to the point that the powers-that-be have a system so fine-tuned that, although it's not 100% certain, it will deter people from doping and hence doping will be a problem of the past.

If that's what you want to believe... errrrr, be my guest.

Really... I don't know. I guess doping will always be a problem, very hopefully though a lesser problem than it is now.

[One proviso: genetic engineering and gene doping may be the "doping of the future". If so, I have no idea how "anti-doping" will address that one.]

However diminishing returns for the same or increased penalties will hopefully be a significant deterrent.

Also if (may be a big if at present) cases like Ferrari/LA result in successful prosecutions then further doping may be reduced??

And as I've alluded to earlier: the more (variety of tests on samples) tests prospective dopers face, the more circumspect they are likely to be in future doping activities.

 

[Merckx index]

First, did you read the link I provided? It cites Japanese exposure of 2mg per day of DEHP (IV bags are in that order - 3mg and up).

Well, no, according to that same link, exposure from transfusion can be up to 600 mg, far more than exposure from food reported in the Japanese. Moreover, studies of Japanese that I have seen show that their urine levels of DEHP are nowhere close to those resulting from transfusion. The critical point is not how much DEHP is ingested, but how much ends up in the urine, where the test actually occurs. Even if amounts of DEHP were consumed in food that were comparable to those leaching out of blood bags--and they aren't, according to this link--DEHP that goes directly into the bloodstream will result in higher urine levels.

Another factor to consider is that it isn't just the very high levels that are a sign of transfusion, but a sudden spike in levels. One does not see such spikes when DEHP results from food, since the daily intake is fairly consistent. Transfusion, of course, results in a spike that drops dramatically after a couple of days.

Second, Segura et al's study in Transfusion 50 (1) states,

So, Segura et al even allow for 'higher environmental exposure'. Had more for you, but I'm not going to trace all the articles all over again.

Segura et al. were simply speculating, they had no evidence at all that very high DEHP levels resulted from environmental exposure. Since these outliers were all athletes, a much more likely conclusion is blood transfusion, which they also suggested.

A lot more work needs to go into the methodology of the plasticiser test before it will be robust enough to be a suitable WADA test.

To be a standalone test, yes. But most of the talk has been as a supplement to other evidence. Bert's case is a good example. Let us suppose that the DEHP tests announced last year were valid, and he really did have the reported levels. Those levels alone might not be good enough to convict him of blood doping, but they certainly add strong support to other evidence, namely, the fact that transfusion better accounts for his CB test than contamination does.

 

[Special_oz_ed]

Here we go again.

Merckx index,

Well, no, according to that same link, exposure from transfusion can be up to 600 mg, far more than exposure from food reported in the Japanese...

600mg is possible, but under certain conditions, and certainly very unusual. It, like high measures of DEHP metobolites in the Segura study (or others), are outliers.

Another factor to consider is that it isn't just the very high levels that are a sign of transfusion, but a sudden spike in levels. One does not see such spikes when DEHP results from food, since the daily intake is fairly consistent. Transfusion, of course, results in a spike that drops dramatically after a couple of days.

Sudden spike...sure, it could indicate a transfusion. But DEHP results from food assumed a constant environmental exposure, not a one-off exposure. That is why they are constant. Say a person went from a low DEHP exposure country to Japan, what would the result be? A spike, would it not? (Even if the spike may not be as high as for a transfusion, for example).

Segura et al. were simply speculating, they had no evidence at all that very high DEHP levels resulted from environmental exposure. Since these outliers were all athletes, a much more likely conclusion is blood transfusion, which they also suggested.

Yes, but science tests 'likely conclusions' rather than just assumes them to be true. Segura also had no evidence that the very high DEHP levels in athletes came from transfusion. That's my point. Before coming to a conclusion like Segura has, a robust method rules out *all* other possible or likely avenues of exposure.

 

[Merckx index]

Merckx index,
600mg is possible, but under certain conditions, and certainly very unusual. It, like high measures of DEHP metobolites in the Segura study (or others), are outliers.

What is your source for this assertion? I didn't see that mentioned in the link you cited. But it doesn't really matter, because the range presented is 14-600 mg. IOW, the low end of the range is 7x greater than the high levels of food contamination reported in Japanese. If the low end is this high, how many times higher is a typical transfusion exposure? Probably 20-50 times.

Sudden spike...sure, it could indicate a transfusion. But DEHP results from food assumed a constant environmental exposure, not a one-off exposure. That is why they are constant. Say a person went from a low DEHP exposure country to Japan, what would the result be? A spike, would it not? (Even if the spike may not be as high as for a transfusion, for example).

It would be nowhere remotely close to the spike seen following transfusion. Japanese food levels are only 2-3x levels in Holland, for example, and 7-8 times those in Americans, and it would take time for the changes in food to work their way through the system. As the link discusses, there is some variation in levels ingested even in individuals in a particular country, and this may be reflected in changes in urine levels of the metabolites. But these fluctuations are considerably less than the spike of 10-20 times seen following transfusion, and which occurs within hours.

Yes, but science tests 'likely conclusions' rather than just assumes them to be true. Segura also had no evidence that the very high DEHP levels in athletes came from transfusion. That's my point. Before coming to a conclusion like Segura has, a robust method rules out *all* other possible or likely avenues of exposure.

Of course they had evidence--they just showed that such levels typically result from transfusion. Again, there is no evidence that levels this high result from food contamination. I'm still waiting for you to provide a single study of non-transfused individuals with levels as high as those reported for transfusion. The small study I cited long ago in which levels fluctuated, and a different method of urine collection was employed, is the only one I know.

 

[Special_oz_ed]

Round and round the merry-go-round

Merckx index,

What is your source for this assertion?

Yeah, you keep asking this question, yet happily provide no source for your own assertions except, 'A small study...'.

I spent a number of hours reading peer-reviewed studies the other day (because I have access to online journals), had prepared a response with details, and for some reason when I went to post it, the forum had logged me out. Unfortunately I didn't save the material to a different doc on my computer. I'm not going to repeat the effort.

The issue is, there has not been nearly enough work done in the area of DEHP exposure across industries, products and in food contamination events to rule them out. All I'm saying is that - even if unlikely - it is still possible to be exposed to DEHP levels within the range of those experienced by transfused patients. Now, for a test to be robust, it MUST rule out other possibilities through serious measurements. That means, Tour participants must be measured for their exposure to DEHP (given its short half-life in the body), averages taken, audits of sources of DEHP apart from transfusion taken, and then a robust methodology worked out to come up with a relevant cut-off point for certain DEHP exposure due to transfusion.

How do we know what the average exposure of Tour riders is to DEHP? Segura has gone from measures of general population and athletes in one country, then transferred those results to a different country under different circumstances. That's ******** as a methodology. You could drive a truck through the holes in it.

It would be nowhere remotely close to the spike seen following transfusion. Japanese food levels are only 2-3x levels in Holland, for example, and 7-8 times those in Americans...there is some variation in levels ingested even in individuals in a particular country...But these fluctuations are considerably less than the spike of 10-20 times seen following transfusion, and which occurs within hours.

Japanese levels 7-8 times those of Americans...that's close to 10 times, I believe. Also, we're talking averages here, aren't we? And you know how averages work, don't you?

I've read Segura's study at least four times now, and the same problems keep raising their head - the authors simply assume the athletes were transfusing...and HE KNOWS NOTHING ABOUT THEIR MEDICAL OR ENVIRONMENTAL EXPOSURE! And there's only four of them!

Next, and in the study authors' own words,

In our study,medical treatments with PVC devices did
not increase the day-long concentrations of DEHP metabolites and, thus, they would not probably explain positive results. Nevertheless, the possibility of other sources of substantial DEHP exposure cannot be completely excluded.(p148, Transfusion 50(1) 2010)

Shall I point out that Segura et al say, other sources of substantial DEHP exposure cannot be completely excluded?

I'm still waiting for you to provide a single study of non-transfused individuals with levels as high as those reported for transfusion.

Well just look at the link I posted. It's easily seen that some industry exposed individuals clearly have daily levels as high as transfused individuals.

See, the way this game works is, if you're trying to prove that high DEHP metobolites = blood doping, then you have to provide concrete evidence, not me. I'm the one who comes along and says, "The studies you are relying upon have methodological gaps and/or aren't definitive for x, y, and z reasons." Then you go back and find some more evidence that is much more robust. The burden of proof is on you, not me. I'm happy to agree with you that it *may,* just *may* indicate of blood-doping, but it isn't a definitive test by any stretch of the imagination.

The small study I cited long ago in which levels fluctuated, and a different method of urine collection was employed, is the only one I know.

Small studies are at best suggestive of a path of further investigation, no more. I can equally say that a recent study that I read argues that no way has there been sufficient testing in the area of DEHP exposure (e.g., in offices etc) to determine average levels in the general population.

So, I think we'll have to agree to disagree on this one. You want to suggest that the DEHP test is water-tight (probably proving Contador doped). ALL I'm saying is, no it ain't. I'm not trying to defend AC; not trying to say the test won't be able to be used in the future. ALL I'm saying is that, at the moment, it's not robust enough.

 

[JA.Tri]

I don't suggest the test is watertight.

I do believe that source of DEHP/plasticizer needs to be identified. (Depending on forum: Balance of Probabilities/beyond reasonable doubt) Other wise we are left with the CB type issue.

Refer to Special_oz_ed post:

"The issue is, there has not been nearly enough work done in the area of DEHP exposure across industries, products and in food contamination events to rule them out. All I'm saying is that - even if unlikely - it is still possible to be exposed to DEHP levels within the range of those experienced by transfused patients. Now, for a test to be robust, it MUST rule out other possibilities through serious measurements. That means, Tour participants must be measured for their exposure to DEHP (given its short half-life in the body), averages taken, audits of sources of DEHP apart from transfusion taken, and then a robust methodology worked out to come up with a relevant cut-off point for certain DEHP exposure due to transfusion."

The above para mentions "exposure". While exposure is pertinent, surely detected levels is issue (??).

I have taken that "exposed to DEHP levels" is intended to be read as "DEPH levels detected in urine".

I agree that other sources of exposure must be eliminated...however that can be done on a case by case basis.

For example (to be extreme): industrial chemists in plastics have similar DEHP urine levels to that of transfusion patients. This set of subjects will not include Pro Cyclists. OTOH external (non-transfusing) contamination is experienced in an area populated by a group of cyclists and identified as such. Any DEPH positive detected will/should take this into account. Please note that this does not give riders carte blanche...extreme readings would still need to be explained.

Further quote Special_oz_ed:

"Japanese levels 7-8 times those of Americans...that's close to 10 times, I believe. Also, we're talking averages here, aren't we? And you know how averages work, don't you?"

(Yes the issue of averages must be addressed. And yes, background and minimum detected/maximum allowed levels must be established)

"I've read Segura's study at least four times now, and the same problems keep raising their head - the authors simply assume the athletes were transfusing...and HE KNOWS NOTHING ABOUT THEIR MEDICAL OR ENVIRONMENTAL EXPOSURE! And there's only four of them! "

(Valid point, further investigation warranted)

"How do we know what the average exposure of Tour riders is to DEHP? Segura has gone from measures of general population and athletes in one country, then transferred those results to a different country under different circumstances. That's ******** as a methodology. You could drive a truck through the holes in it."

(What is 3sigma levels of DEPH urine readings? Perhaps DEPH could be added to the BioPassport)

"Shall I point out that Segura et al say, other sources of substantial DEHP exposure cannot be completely excluded?"

(Refer back to standard of proof and case by case basis. It may be that the particular circumstances can either completely exclude alternative DEHP exposure or the burden of proof may be met)

As a result, my guess (from reading posts etc) is that DEPH will be a supplementary test/BPassport factor. However how far acceptance testing has progressed is the great unknown...perhaps these issues have been addressed??

 

[JA.Tri]

watertight?

I don't suggest the test is watertight.

I do believe that source of DEHP/plasticizer needs to be identified. (Depending on forum: Balance of Probabilities/beyond reasonable doubt) Other wise we are left with the CB type issue.

Refer to Special_oz_ed post:

"The issue is, there has not been nearly enough work done in the area of DEHP exposure across industries, products and in food contamination events to rule them out. All I'm saying is that - even if unlikely - it is still possible to be exposed to DEHP levels within the range of those experienced by transfused patients. Now, for a test to be robust, it MUST rule out other possibilities through serious measurements. That means, Tour participants must be measured for their exposure to DEHP (given its short half-life in the body), averages taken, audits of sources of DEHP apart from transfusion taken, and then a robust methodology worked out to come up with a relevant cut-off point for certain DEHP exposure due to transfusion."

The above para mentions "exposure". While exposure is pertinent, surely detected levels is issue (??).

I have taken that "exposed to DEHP levels" is intended to be read as "DEPH levels detected in urine".

I agree that other sources of exposure must be eliminated...however, in many cases, that can be done on a case by case basis.

For example (to be extreme): industrial chemists in plastics have similar DEHP urine levels to that of transfusion patients. This set of subjects will not include Pro Cyclists. OTOH external (non-transfusing) contamination is experienced in an area populated by a group of cyclists and identified as such. Any DEPH positive detected will/should take this into account. Please note that this does not give riders carte blanche...extreme readings would still need to be explained.

Further quote Special_oz_ed:

"Japanese levels 7-8 times those of Americans...that's close to 10 times, I believe. Also, we're talking averages here, aren't we? And you know how averages work, don't you?"

(Yes the issue of averages must be addressed. And yes, background and minimum detected/maximum allowed levels must be established)

"I've read Segura's study at least four times now, and the same problems keep raising their head - the authors simply assume the athletes were transfusing...and HE KNOWS NOTHING ABOUT THEIR MEDICAL OR ENVIRONMENTAL EXPOSURE! And there's only four of them! "

(Valid point, further investigation warranted)

"How do we know what the average exposure of Tour riders is to DEHP? Segura has gone from measures of general population and athletes in one country, then transferred those results to a different country under different circumstances. That's ******** as a methodology. You could drive a truck through the holes in it."

(What is 3sigma levels of DEPH urine readings? Perhaps DEPH could be added to the BioPassport)

"Shall I point out that Segura et al say, other sources of substantial DEHP exposure cannot be completely excluded?"

(Refer back to standard of proof and case by case basis. It may be that the particular circumstances can either completely exclude alternative DEHP exposure or the burden of proof may be met)

As a result, my guess (from reading posts etc) is that DEPH will be a supplementary test/BPassport factor. However how far acceptance testing has progressed is the great unknown...perhaps these issues have been addressed??

 

[Merckx index]

Yeah, you keep asking this question, yet happily provide no source for your own assertions except, 'A small study...'.

I posted these links in two previous threads, but will post two of them here.

http://www.ncbi.nlm.nih.gov/pmc/articles/P...22/?tool=pubmed

This is a study of 2500 subjects. While there were a few outliers with very high DEHP urinary metabolite levels, they are very rare.

http://www.ncbi.nlm.nih.gov/pubmed/20797930

This is a small study, which you seemed to think I was using in support of my point that controls do not have levels comparable to transfused patients. On the contrary, this small study was the one I found which suggested controls could have fluctuations of metabolite levels reaching those found in transfused patients. At the time I first posted it, I suggested it would be of interest to Bert, if his DEHP test ever became part of his case.

How do we know what the average exposure of Tour riders is to DEHP? Segura has gone from measures of general population and athletes in one country, then transferred those results to a different country under different circumstances. That's ******** as a methodology. You could drive a truck through the holes in it.

Segura’s study is only one of many. There are literally dozens of them, studies of people all over the world, including several in occupations in which exposure is higher than normal. all easily available on PubMed. Here are just a few:

http://www.ncbi.nlm.nih.gov/pubmed/21477864 - China
http://www.ncbi.nlm.nih.gov/pubmed/12963402 - Germany
http://www.ncbi.nlm.nih.gov/pubmed/16078637 - Japan
http://www.ncbi.nlm.nih.gov/pubmed/21395215 - several Asian countries
http://www.ncbi.nlm.nih.gov/pubmed/20010977 - occupational groups
http://www.ncbi.nlm.nih.gov/pubmed/18948546 - industries

The last link reports that DEHP metabolite levels up to 8x normal are found in workers in PVC manufacturing. Another study of Chinese workers in the same industry claimed even higher increases:

http://www.ncbi.nlm.nih.gov/pubmed/20010977

So yes, environmental exposure can raise these levels substantially. But these are exceptional circumstances, it seems unlikely that they would apply to athletes. There are also some "control" (quotes because I don't know their background/occupation) individuals in some general population studies (i.e., the German one) with very high levels. However, if you look at the standard error or deviation in these studies, it is quite small. The very high values result from a skewing at higher levels, IOW, the distribution is not normal. This suggests that these outliers probably have unusual circumstances that contribute to their very high levels.

I do agree with you that a baseline for an athlete would need to be established, much as is done with the passport. This would protect those relatively few athletes who might have very high values. But remember, too, that the spike is also very telling. This is why the small study I cited at the beginning of this post is significant, because a few individuals in this small study did exhibit such spikes. But again, this is the only study I know of where this was demonstrated.

 

[Special_oz_ed]

Thanks for clarifying

Merckx index,

This is a quick post. Thanks for clarifying. It helped - I think we've been arguing at cross purposes. I've only been able to skim read two of the links. The small study you cite is very interesting, if in need of further work. I think it demonstrates not only the difficulty with the DEHP test as it stands, but perhaps also that the exact mechanism of oxidation of DEHP to its metabolites is not understood very well at all - the rates of oxidation appear to differ wildly for some people. What would also be of incredible importance is the relationship of the kind of rapid hydration-dehydration that cyclists undergo in something like the Tour and its effect on metabolising DEHP. It's hardly a normal circumstance.

From your later set of references, I checked out the paper related to Germany and spotted this:

Concentrations were found to vary strongly from phthalate to phthalate and subject to subject with differences spanning more than three orders of magnitude.

That's a pretty big variation - up to three orders of magnitude (the highest reading being 1000 times more than the lowest)!

Gotta go.

 

[Cimber]

Been away from internet access for about 2 weeks so bare with me if this has been discussed since (or even before):

-Has there been any official announcements about finding plasticizers in Berti's tests or are it still rumours?
-Do we know anything about the exact levels found?
-Has the test been approved? i.e. will it be useful in court?
-Do we know if WADA will include platicizer as evidence at CAS?

 

[python]

Been away from internet access for about 2 weeks so bare with me if this has been discussed since (or even before):

-Has there been any official announcements about finding plasticizers in Berti's

There hasn't been. But some believe the initial mention in a german source is the covered up official fact. the only news (take it for what it's worth) was that the uci officially stated that the plasticizer is NOT figuring in the cas appeal. wada did NOT comment.

-Do we know anything about the exact levels found?

yes and no. nothing new other than the original speculation about the two metabolites concentration on three different days including the clen positive.

-Has the test been approved? i.e. will it be useful in court?

not known but likely not yet. but according to some dated GENERAL statements by wada's howman, it can be useful in court as a corroborative evidence.

-Do we know if WADA will include plasticizer as evidence at CAS?

[/QUOTE]see above.

 

[Merckx index]

Merckx index,

This is a quick post. Thanks for clarifying. It helped - I think we've been arguing at cross purposes. I've only been able to skim read two of the links. The small study you cite is very interesting, if in need of further work. I think it demonstrates not only the difficulty with the DEHP test as it stands, but perhaps also that the exact mechanism of oxidation of DEHP to its metabolites is not understood very well at all - the rates of oxidation appear to differ wildly for some people. What would also be of incredible importance is the relationship of the kind of rapid hydration-dehydration that cyclists undergo in something like the Tour and its effect on metabolising DEHP. It's hardly a normal circumstance.

From your later set of references, I checked out the paper related to Germany and spotted this:



That's a pretty big variation - up to three orders of magnitude (the highest reading being 1000 times more than the lowest)!

Gotta go.

Actually I had not seen the German study before I went back to find the other links. I would put it with the Preau study (small study with fluctuations) showing that very high levels of DEHP metabolites can be found in "controls" (again, quotes because we don't know whether these individuals may have been in unusual circumstances). What makes this study unusual is that it was relatively small, less than one hundred subjects, yet they still found a few individuals with very high levels. Many other studies involving, say, 30-100 subjects that I have seen (and did not post) did not find such outliers, and that was the basis of my earlier statements. The study of 2500 subjects shows they are definitely there, but indicates they are quite rare, less than one in a hundred. The German study suggests possibly otherwise; though still not common by any means, they might be frequent enough to cause concern about false positives.

I think the most useful link I posted is the Hines et al study (listed as "industry"). Their main findings were:

1) for most industrial worker classes studied there was no significant effect on urinary levels;
2) workers in PVC industry are an exception--and again, to be fair, I hadn't seen this before, either. They have median levels 4-5x those of the other subjects, and the maximum levels found (highest individual) can be 10-20 times greater than the maximum found in controls. This is in general agreement with the study of Chinese PVC workers I cited, though there the increase was even larger, 100x! Moreover, the levels are higher at the end of the work shift than at an earlier time. So in this special environment, spikes are possible.

So at this point I would summarize the situation as follows (and modify my earlier statements):

1) DEHP levels are not much affected by most environments, but PVC workers are a glaring exception;
2) there is some effect of diet, but that is more modest;
3) there are some individuals that exhibit very high levels apparently not the result of some unusual environmental or dietary circumstance.

As I said before, I agree very much for the need for a baseline. OTOH, if the primary value of this test turns out to be retrospective (because of the ease in which riders can use DEHP-free transfusion methods), this could create problems even for testing of old samples. A rider who tested very high for some samples taken several years ago could argue that he had a high baseline at that time, and it would be very difficult to prove otherwise.

Finally, though, while these studies suggests problems for a standalone DEHP test, I don't think they are at all serious for the proposed use as a supplement to other tests. If a DEHP value suggested with 80-90% probability that a rider was transfusing, one might not feel it fair to convict on this basis. But if independent evidence--such as CB in Bert's case--suggests a high probability of doping, then this 80-90% or whatever probability becomes strong additional evidence. If two independent tests provided 90% probability each, combined they would provide 99% probability.

 

[Special_oz_ed]

Merckx index,

I think we're in furious agreement for the most part.

Actually I had not seen the German study before I went back to find the other links.

I chose the German study because one of the papers I had cited in 'the lost post' was a study of German and another from Norwegian(?) subjects and both showed higher average exposure levels to DEHP than in other countries.