letter to ATSDR on dioxin MDL

["Jon Campbell" <jon@cqs.com>]

From: Jon Campbell

To: Agency for Toxic Substances and Disease Registry
Division of Toxicology
Toxicology Research Branch
1600 Clifton Road, E-29
Atlanta, GA 30333

Subject: ATSDR Update of Toxicological Profile for Chlorinated
Dibenzo-p-Dioxins

Greetings,

Recently your office issued a document entitled Toxicological Profile for
Chlorinated Dibenzo-p Dioxins, Update, Draft for Public Comment. This letter
is to comment on this update and provide you data for your serious
consideration.

I want to first say that I am greatly appreciative that in this document you
have cited perhaps the largest amount of dioxin-related information
available anywhere publicly.

However, that said, I am most concerned with, and I object to, your proposed
Minimum Dose Level (MDL) for TCDD-equivalent of 1 pg/kg/day, specified on
page 216 of the document in question. I do not understand how your agency,
having reviewed the same cancer and non-cancer data as the Environmental
Protection Agency, can come up with an MDL which is 200 times as large as
the “maximum acceptable dose” published by the EPA in the 1994 Dioxin
Reassessment.

1. In particular, simple mathematics shows that your MDL is clearly not
protective of human health. First, the EPA has calculated that the lowest
body burden level known to cause harm in humans is 14 ng/kg. Using the ATSDR
’s proposed MDL of 1 pg/kg/day, a person exposed for 70 years, assuming no
elimination, would accumulate levels of over 25 ng/kg average in some parts
of the body. Since the mechanism for elimination of dioxin, especially at
these lower concentrations, is extremely slow and varies by type of cells,
we can only assume that nearly the full concentration will exist in some
parts of the body for a large percentage of the population. This variation
in dioxin body burden is confirmed in the autopsy results published in your
proposed Toxicological Profile. General exposures at this MDL will expose a
very large proportion of the population to dioxin-induced cancer and other
dioxin-related diseases and afflictions.

2. “Background” dioxin exposure by a large proportion of the U.S. population
to levels at the proposed MDL are already probably causing a nationwide
health crisis. The consumption of dioxin-contaminated meat and dairy
products in the U.S. has exposed the majority of U.S. residents to levels of
dioxin of approximately 70-100 picograms of dioxin TEQ per day. Today, one
out of every two men, and one out of every three women in the U.S. will
contract cancer in their lifetimes. The cancers seeing the largest increases
are those that are related to endocrine dysfunction, such as pancreatic,
prostate, breast, ovarian, and cervical. Dioxin is the most powerful
endocrine disrupter known, and has the steepest cancer dose-response curve
of any organic chemical known. We must assume that dioxin exposure is likely
partially responsible for the dramatic increase in cancer during the last 20
years.

In addition, millions of U.S. women suffer from endometriosis, an affliction
all but unknown at the beginning of this century. Endometriosis is a
dysplasic affliction: it is caused by the reproduction of the wrong type of
tissue (endometrium) on the walls of the fallopian tubes. This in turn is
caused by an improper or disrupted genetic message reaching the cell – the
same kind of disruption that dioxin and dioxin-like chemicals are known to
cause.
There are many other diseases and afflictions linked to or correlated with
exposure to dioxins or PCBs. Attention Deficit Disorder, diabetes, chronic
fatigue syndrome, rare nervous and blood disorders have been so linked.

Agencies of the U.S. government such as ATSDR must provide MDL standards
that reduce chronic dioxin exposure below current “background” levels, to
prevent even higher body burdens than exist today. Such action will prompt
action by consumers and food advocacy groups to reduce contaminated meat and
dairy intake, and encourage changes in industry and government to reduce
dioxin production.

There is, in fact, no MDL that is protective against health effects of
dioxin exposure. Each picogram of TCDD contains 1.88 billion molecules, each
of which is capable of disrupting the normal actions of a cell, in ways that
are undetectable by our immune system. There is just no way to know whether
disrupted cells will suddenly divide uncontrollably, causing cancer, or
reproduce the wrong kind of cell (dysplasia), or disrupt nerve messages, or
cause an improper immune response.

The ATSDR should really specify an MDL of ZERO for dioxin. At the very
least, the ATSDR must affirm the lower “acceptable” dioxin dose published in
the EPA Dioxin Reassessment of .006 pg/kg/day.

       Sincerely,
        Jon Campbell
        February 3, 1998