Sunday, September 13, 2015

Breast Milk and PFASs - Part 10

Back to the real focus.

Remember why the Breastfeeding Paper authors focused on PFASs as a health concern.
...a major concern is that PFAS exposure may undermine childhood immunization programs.
Remember the paper they cited to substantiate that concern; the Antibody Paper.

Now remember what the Antibody Paper authors said about the maternal serum concentration at week 32 of pregnancy.
The prenatal exposure level, as indicated by the mother’s serum concentration during pregnancy, was less clearly associated with the antibody outcomes.
The Antibody Paper tells us this:
In a structural equation model, a 2-fold greater concentration of major PFCs in child serum was associated with a difference of −49% (95% CI, −67% to −23%) in the overall antibody concentration.
This is based on looking at the PFASs at age 5 and 7 years and comparing them to the antibody concentrations found.  Doubling the amount of PFASs was shown by their model to decrease the overall antibody concentration by about 50%.

Let's look at the reality of that population of 656 in the study.  After 5 years, 532 children showed this level of antibody concentrations prebooster:

Source: Antibody Paper - Table 1 excerpt

For tetanus, 75% of the values for the 532 children were above 0.1 IU/mL which we are told: considered an important indicator of protection in accordance with the public health rationale for routine vaccinations.
75% of all these children had antibody concentrations above the protective level for tetanus and almost 75% of these children had antibody concentrations above the protective level for diphtheria.

That is 75% for of the 532 children from the Faroe Islands who were specifically chosen for this study because:
frequent intake of marine food is associated with increased exposures to PFCs
If 75% of these kids with a suspected increased exposure to PFASs for both them and the mother are protected (above 0.1 IU/mL), then what would we expect the antibody concentrations to be in a child born to a mother in San Antonio, Texas?

Even if the Antibody Paper's model is true, and we see a 50% reduction in antibodies with a 2-fold increase in exposure to PFASs, Does breastfeeding there in the Faroe Islands or in San Antonio, Texas produce a 2-fold increase in PFASs for the child?

Does 6 months worth of breastfeeding produce a noticeable increase in PFASs whereby the antibodies would decrease below the 0.1 IU/mL protection level?  Is there a statistical difference between children who are breastfed falling below the 0.1 IU/mL protection level compared to children who were not breastfed.

That's the question they should have asked and that's the statistics they should have reported.

Armed with that, one could then decide to forgo breastfeeding benefits in order to reduce the chance of their child falling below the antibody protective level of 0.1 IU/mL.

Every time I read the Breastfeeding Paper I came up with more" huh?"  Things I needed to know were left out.  When I realized just how how off the mother's serum concentrations were from the population of mothers they were pulled from, the paper's findings became less and less credible.

Here is what I know from the Breastfeeding Paper:

They have 81 mothers and those 81 mothers have 81 children.  From this 81 they were able to get data.

Ignoring the mother's serum levels reported for PFOS, we see that 68 children from these 81 mothers had their blood tested at age 11 months.  We are shown data that tells us how much PFOS were in the kids at 11 months.

We also have data for PFOS in these kids at 18 months.  We are not told if these are the same kids from testing at 11 months, or a new set of the kids from the 81 tested at 18 months.

We are told this:
Figure 1 shows the trajectories of the five major PFAS for the 12 children with complete observations from all examinations.
What I understand this to mean is that only 12 children of the 80 mothers had blood sampled for PFOS at 11 months and 18 months.

We are told that the amount of time some of these 81 children were exclusively breastfed was 4.5 months.  We are told that some of these 81 children were partially breastfed for 4 months, and that some of these 81 children were only breastfed for one month or less.

What we are not told is how many of the 73 women of the 81 who replied to the question on breastfeeding fall into each of those three groups.

What were are not told is' of the 73 women of the 81 who replied to the question on breastfeeding, what the concentration of PFOS for each of these three groups.

What we are instead given is a graph:

Source: Breastfeeding Paper - Figure 1

We are told by the authors of the Breastfeeding Paper this:
The child with the lowest concentrations (blue dotted line) was not breastfed at all, whereas the child with the highest PFOS concentration (black solid line) was breastfed exclusively in 6 months and was partially breastfed during the following 5 months.
What we are not told - and I have looked and looked to make sure I did not overlook it - is what the other lines and colors represent.  That bit of information was left out.  Oops!

Okay, you got 12 kids with complete data.  One of them was breastfed exclusively and the other was not.  Does the blue dotted line represent the population of those who do not breastfeed?  Does the black solid line represent the population that exclusively breastfeeds?

What do the other lines show?

Here is what I want to know:

  1. What was the concentration of PFOS at 11 months for the kids who were exclusively breastfed?
  2. What was the concentration of PFOS at 11 months for the kids who were not breastfed?
  3. What was the concentration of PFOS at 18 months for the kids who were exclusively breastfed?
  4. What was the concentration of PFOS at 18 months for the kids who were not breastfed?

With that data, one could see if there is a statistical difference between the two groups.  Why was that not done?  Why focus on showing us a graph of 12 of them and leave out the explanation of the data for 10 of those 12?

I am unwilling to look at two children and say that their PFOS values represent the two groups.  In particular, the PFOS values for the not breastfed kid - the blue dotted line - is way below the lowest IQR reported for 68 of the kids tested at 11 months.

So there you have it.  I have beat this dead horse as much as I can.

If you are going to forgo the benefits of breastfeeding because you are concerned about passing on PFASs to your baby, then you would be making a big mistake if the reason for doing so is based on this paper's findings.

Thanks for reading.

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