One group of chemicals — endocrine disruptors — can interfere with the functional of the human hormone system, even when exposure levels are extremely low. Some can mimic human hormones or otherwise interfere with hormone-controlled systems, which can block (or put into overdrive) a range of biological processes.
Many pesticides are endocrine disruptors, and scientists have linked exposure to a wide range of human health harms.
For example, endocrine-disrupting chemicals can damage the reproductive system in a number of ways. Some kill or damage cells; if these are sperm cells or oocytes, infertility can result. Others alter DNA structure, causing gene mutations that may result in birth defects or an inability to conceive.
Changes in hormone levels or function caused by endocrine disruptors affect infants and children more than adults, and can result in abnormalities in reproduction, growth, and development, as well as cancer and immune system disorders. Timing of exposure is key, and often more important than the “dose.”
Some chemicals can even cause “epigenetic” effects, meaning they change the way genes are expressed — not just for those exposed, but potentially for future generations, too.
More detailed explanations — and compelling evidence of the scope of the problem — are outlined in Generations at Risk, a book co-authored by Dr. Ted Schettler, a former member of PAN’s Board of Directors.
PAN Summary Endocrine Disruptor Rating
Because ratings from different sources sometimes conflict with each other, PAN created a summary ED designation that designates any chemical that is listed as potentially endocrine disrupting by any of the sources is ranked as a Suspected endocrine disruptor.
While it is clear that many pesticides are capable of having endocrine-disrupting effects, no “official” list of these chemicals has yet been compiled in the United States. While the U.S. EPA does conduct testing, it provides no published list of endocrine disrupting chemicals. We provide information from one independent U.S. source— Our Stolen Future, as well as from the Danish government and the E.U.
The absence of a chemical on the summary list does not necessarily mean it is not an endocrine disruptor. It may mean that it has not yet been evaluated or data are not available.
European ED Rating
In December 1999, the European Commission adopted a strategy for addressing the problem of endocrine-disrupting chemicals. Part of this strategy was to establish a priority list of substances for further evaluation of their role in endocrine disruption. The list is used to identify substances for priority testing when test methods become available, and to identify gaps in knowledge of the toxicity and exposure pathways.
Prioritization was based on evidence of endocrine disruption in humans or animals and on the exposure potential for the chemical based on persistence in the environment and the amount of the substance produced. The starting point of the study was a working list, compiled from the lists of suspected endocrine disrupting chemicals drawn up by various organizations as well as from an up-to-date literature search.
The list contains three categories of endocrine disrupting chemicals:
- Group I : At least one study providing evidence of endocrine disruption in an intact organism. Not a formal weight of evidence approach.
- Group II : Potential for endocrine disruption. In vitro data indicating potential for endocrine disruption in intact organisms. Also includes effects in-vivo that may, or may not, be ED-mediated. May include structural analyses and metabolic considerations
- Group III : Substances which meet the criteria of High Production Volume and/or persistence in the environment for which: a) no or insufficient data are available, or b) sufficient data are available for evaluation, but the compounds are not presently considered to be endocrine disrupters.
The European Commission maintains a Endocrine Disruptors webpage with the current list of priority chemicals and action being taken to reduce exposure to these substances.
Danish EPA Report
In 2003, the Danish EPA published a list of compounds used as “inerts” or adjuvants in pesticide products which – based on available information – the Danish EPA considers to have endocrine disrupting (estrogenic) effects, or to be capable of decomposing into estrogenic compounds.
This builds on a report the same agency published in 1995 entitled “Male Reproductive Health and Environmental Chemicals with Estrogenic Effects”. Following up on the report, the Danish Government announced the goal of phasing out by the year 2000 all pesticides containing estrogenic auxiliary matters. The chemicals are added to the products for various reasons – e.g. to enhance the effect of the active ingredients in the pesticide.
The current listing of endocrine disrupting chemicals is available on a site maintained by the Danish EPA.
Our Stolen Future
A list of suspected endocrine disrupting chemicals was published in the scientific literature in 1993 by Theo Colborn, followed by the popular book for the layperson Our Stolen Future (see full citations below).
The book highlighted the effects of endocrine disrupting chemicals on humans and the environment and was instrumental in raising public awareness of the need for more research.In this reference, chemicals are not ranked according to their endocrine-disrupting effects, thus the rating simply describes whether the chemical is contained in the reference or not.
The Our Stolen Future list is also available online.
Resources:
U.S. EPA Endocrine Disruptor Screening Program
E-hormone: Gateway to Environmental Signaling (Tulane University)
Developmental effects of endocrine-disrupting chemicals in wildlife and hum