Coffee, Acrylamide, and Proposition 65 - Part 5

In the case of acrylamide in coffee, how do we establish there is a "significant amount" of acrylamide "in the products they purchase?"

Based on what we know so far, California has established a "Safe Harbor" concentration of 0.2 micrograms per day. Any thing that is at this concentration or less in the "products they purchase" would never have to be disclosed.

That is, California has determined that your need to be warned ends when the concentration of the chemical presents a cancer risk of less than one additional cancer in 100,000. Less than 0.2 micrograms that would be consumed when using the product, would not require the warning:

“This product can expose you to a chemical [or chemicals] known to the State of California to cause cancer."

let's make sure we are all clear on this. 0.2 micrograms presents a cancer risk that California tells us that y'all don't need to worry yer perduy lil' head about this here chemical. Which means we go back to that proverbial line in the sand...

That line - threshold - for acrylamide is 0.2 micrograms per day. We don't say that less than 0.2 micrograms is "safe" what California claims is this:

...such chemical shall be deemed to pose no significant risk within the meaning of Section 25249.10(c) of the Act.

Section 25249.10(c):

 An exposure for which the person responsible can show that the exposure poses no significant risk assuming lifetime exposure at the level in question for substances known to the state to cause cancer...

So on the "Safe" side of the line in the sand lies acrylamide at a 0.2 micrograms/day concentration that "pose no significant risk."

Which means what for the other side of the line? If on one side it poses "no significant risk" does the other side of that line therefore pose a "significant" risk? If less than one in 100,000 is "no significant risk", is 1.01 in 100,000 a "significant" risk? What about two in 100,000?

Oh what a corner Proposition 65 painted us into.

This now requires us to get back into some math. That risk calculation of one in 100,000, or 1.01 in 100,000, or 2 in 100,000 is calculated based on that linear line we have discussed. Remember, that line is forced so that zero dose = zero risk.



Let's look at a recognized definition of cancer risk:

A slope factor is an estimate of a chemical’s carcinogenic potency, or potential, for causing cancer. If adequate information about the level of exposure, frequency of exposure, and length of exposure to a particular carcinogen is available, an estimate of excess cancer risk associated with the exposure can be calculated using the slope factor for that carcinogen.

...an estimate of excess cancer risk can be calculated...

 Specifically, to obtain risk estimates, the estimated chronic exposure dose (which is averaged over a lifetime or 70 years) is multiplied by the slope factor for that carcinogen.

So that number of 0.2 micrograms per day for acrylamide was determined as the dose that would get an “excess cancer risk” of one cancer above the background chance would appear in a population of 100,000 people.

Here is how the ATSDR guys define it for a cancer risk of one in 1,000,000:

Cancer risk is the likelihood, or chance, of getting cancer. We say “excess cancer risk” because we have a “background risk” of about one in four chances of getting cancer. In other words, in a million people, it is expected that 250,000 individuals would get cancer from a variety of causes.

This is a bit misleading here. Acrylamide risk is based on cancer from acrylamide exposure. We would need to know the background risk of the cancer associated with acrylamide. However, this still works as they are telling us that if you did not drink coffee your chance of cancer is 25,000 in 100,000. If you drink coffee with 0.2 micrograms each day, for 70 years, your chance of cancer is 25,001 in 100,000.

Here is how the ATSDR explains it based on the one in 1,000,000 cancer risk:

If we say that there is a “one in a million” excess cancer risk from a given exposure to a contaminant, we mean that if one million people are exposed to a carcinogen at a certain concentration over their lifetime, then one cancer above the background chance, or the 250,000th cancer, may appear in those million persons from that particular exposure. In order to take into account the uncertainties in the science, the risk numbers used are plausible upper limits of the actual risk based on conservative assumptions. In actuality, the risk is probably somewhat lower than calculated, and in fact may be zero. [ATSDR]

Here is what that calculation looks like for determining the Safe Harbor NOEL for a chemical "known to the State of California to cause cancer." This is how 0.2 micrograms per day for acrylamide was calculated. Note: The term "potency value = slope factor.



Now that we have that out of the way, let's look at the calculated cancer risk that California would claim is in one delicious cup of Pikes.


Next Post: Coffee, Acrylamide, and Proposition 65 - Part 6