Thread by @DBrozeLiveFree

Day 9 of the 2nd phase of the #FluorideLawsuit is resuming with EPA witness Dr. Stanley Barone.

EPA attorney Brandon Adkins wants to talk to Barone about the BMCL (Benchmark Concentration Level)

EPA is first asking Barone about the ability to translate a urinary fluoride level into a fluoride intake level.

Barone says this is not possible (as was testified to by previous FAN witness).

EPA asking Barone about the Physiologically based pharmacokinetic (PBPK) Model and in what cases the EPA will use such a model.

Barone is explaining to Judge Chen his view that several studies show "a lack of linearity" below the 1 mg/L water fluoridation levels.

Barone and the EPA are trying to convince the judge that the effects of fluoride are too unclear below 1 mg.

Judge Chen asks Barone if the Thippeswamy study found more linearity above the 1 mg/L level.

Barone agrees with qualifications.

Judge Chen and Barone are still going back and forth.

Again, this is an example of how the judge seems genuinely interested in getting to the bottom of the science here. He isn't blindly following the govt, and he isn't necessarily on the plaintiffs "side" either.

Barone and Judge Chen discussing absorption of fluoride and excretion.

Judge Chen is wondering if its possible to determine how much fluoride is being absorbed and how much is actually being excreted by the body.

Judge Chen wraps up his questions.

EPA continues questioning of Barone...

Barone says there's more to this equation than just intake of fluoride.

EPA shows Barone a bar graph used by plaintiffs which shows levels of Maternal Urinary Fluoride levels, comparing fluoridated to non-fluoridated populations.

The data from table is from Till, 2018, in the Third Trimester.

EPA asks Barone if what the table shows is accurate. Barone says no. He doesnt think the use of fluoride intake levels are sufficient enough for drawing conclusions.

EPA: Why would you need to do source apportionment for a risk evaluation under TSCA?

Barone: we want to understand what risk is attributed to Condition of Use (COU), in this case, what proportion is attributable to water fluoridation.

Judge Chen has some questions about the Till, 2018, bar graph.

He points to the differences between urinary fluoride concentration, and women in fluoridated areas and non. What else could be account for this difference?

Barone says the analysis here is purely looking at biomarker levels.

Judge Chen: so if women in fluoridated areas have different habits than that could explain these differences?

Barone: It could. What we dont have from this graph is variability and that would account for it.

Judge Chen asking about the source apportionment that was just mentioned.

Barone says the EPA has to understand the COU to be able to understand the risk.

Barone is explaining the risk analysis to Judge Chen using horseshoes as an analogy.

Judge Chen: is there any reason why the EPA in its rulemaking process for TSCA wouldn't do more studies about apportionment?

Barone says that's not the practice, not sure if its prohibited. He says bc TSCA is risk based, they have to have a risk assessment to act.

EPA continues questioning of Barone.

EPA asks Barone if there are any other environmental standards within the EPA that use the COU.

Barone says this is very TSCA specific.

EPA now reading statement to Barone from the EPA redgarding another compoundl NMP (N-Methyl-2-pyrrolidone).

EPA asks Barone about the process EPA used to determine risk with NMP.

EPA goes back to the bar graph from Till, 2018.

EPA: if we were to assume that the 2.41 mg/L level is aggregated data, that level is still below what the NTP found a statistically significant association, correct?

Barone agrees.

Judge Chen has more questions, this time about the process for studying NMP. Asks if the data on NMP was separated into sources of exposure.

Barone answers, and mentions animal studies.

Judge Chen: so animal studies obviously played a big role in that risk assessment...

Barone: it did. Says there was limited human data.

Judge Chen: seems when you dont have as much human data and you have to rely on the animal studies, I see where you put a premium on the PBPK model, is that fair?

Barone agrees, explains the different times they might use a PBPK model.

(this is important bc the EPA has argued the FAN relied too heavily on animal studies that shouldnt be used to make a hazard assessment on fluoride.)

EPA asks Barone if there is enough data to get to the hazard evaluation step of TSCA?

Barone: no. I dont think we can move to determining a threshold or a POD with the current evidence we have.

Barone: The science isn't settled. Making a risk determination with this quality of evidence is highly undesirable.

EPA: and the NTP did not produce a Point of Departure?

Barone: They did not.

EPA: and Dr. Thiessen didnt produce or justify a POD?

Barone: no. I heard a bunch of inferences and vague assumptions which doesnt satisfy TSCA.

EPA: in your view, does the weight of the scientific evidence support selecting a point of departure for water fluoridation at (names several different measurements in mg/L).

Barone: I dont think we have enough evidence to pick a POD around the 1.5 mg/L.

EPA ends their questions with Dr. Barone.

FAN Connett asks for a 5 minute recess before they begin their cross of Barone.