The purpose of this 2005 critical review published in Environmental Science and Technology was to summarize the vast research on endocrine disruptors into a set of “lessons” that can be applied to “the difficult issue of how best to approach future concerns about the potential impacts of other new and emerging contaminants.” Reviews such as these are a necessary part of scientific understanding of any subject. It is often the case, that the mounds of research done on a subject serve only to convolute the facts and decrease the cohesiveness needed in order to learn valid lessons, and test hypotheses which may naturally emerge from organized data. Ultimately, the solving of problems is made easier through endeavors, which stir the pot of current knowledge.
The authors specifically look at research on how endocrine disruptors affect wildlife in order to draw their wider based conclusions on approaching concerns about pharmaceuticals and wildlife. They derived ten lessons from their review of this research. This number seems counter intuitive to common sense approaches in solving problems. Did the authors find lessons that emerged from the data or did they set out to find ten lessons because it is a nice round number to include in their review?
Overview of a Few Lessons
Lesson one is “pay attention to unusual biological observations.” The authors point out that endocrine disruption became an issue when accidental discovered as people either observed or studied the aquatic eco-systems for other factors. The implication is simply that sometimes it only takes paying attention in order to recognize a problem and that this may be a factor in future impacts of contaminants.
Lesson two is “what is normal”. The issue here is that we do not always have the baseline knowledge needed in order to make assumption about what is normal when it comes to bio-markers that may indicate endocrine disruptors. It is argued that baseline data is lacking and acknowledged that it would take huge and monitoring programs, which are extremely targeted in order to gain all baseline data needed.
Lesson three is “one animals poison may not be another’s”. In spite of this statement being recognized for some time in reference to many different substances the authors found that it is not yet easy to ascertain differences in how animals or groups of animals react to endocrine disruptors. This is blamed on a lack of focus on this important issue by researchers studying endocrine disruptors. Predicting which groups of organisms will be “selectively targeted” by these chemicals is said to be a difficult, yet important challenge in endocrine disruptor research.
The fourth lesson is “potency is a key factor”. The authors state that research has shown steroidal estrogens to be “primary causative agents leading to the feminization of fish.” This should in no way limit the focus on other endocrine disruptors as it has also been shown that alkylphenolic chemicals in high enough concentrations can be big contributors to feminization. Lesson six; “beware of continual exposure to low concentrations and mixtures” is really an extension of lesson four. When we consider potency, it should be evident that we should also consider temporal factors of specific dosages as well.
Degradation products may bite is the fifth lesson. This is another lesson that seems should have been learned from the study of other chemicals. An example of the importance of this concept in the study of endocrine disruptors is that steroidal estrogens enter the sewer mainly inactive, until they biodegrade, then they “bite”.
Lesson seven states “beware of nontraditional pollutants from unexpected sources.” It is pointed out that natural organic molecules that may not normally be harmful may be so if introduced to an organism at the wrong time or in the wrong concentration. Perhaps another non-traditional aspect of endocrine disruptor research is stated in lesson nine, which states that “acute toxicity tests may not be very helpful”. This is because acute effects may be delayed in some fish. It is stated that regulatory agencies are developing new testing procedures to account for this fact.
Lesson nine, “central role played by sewage treatment” is in no way surprising, as dealing with human waste has always been a health issue and with increasing waste, and types of contaminants I see no reason why this would change. Lesson ten, at least in part, can be thought about when considering lesson nine. This is because the predicted environmental concentration (PEC) is strongly related to the amount of sewage to be dealt with. The lesson is that “hydrology will tell you where to look.” This is primarily because flow is a big factor in concentration, and as pointed out previously concentration is a big factor in how endocrine disruptors may affect the environment in general.
The Best Approach
The article ends with suggestions on the direction of future endocrine disruptor research. They state there are two possible approaches. One is “compound specific environmental risk assessment.” This is an approach, which compiles all the information about individual endocrine disruptors and uses this information to predict potential effects on wildlife. The contaminants are then regulated based on this data. The other approach is “issue-specific environmental risk assessment.” In this approach, hydrology would be used to find areas likely to have the highest concentrations of endocrine disuptors. The biota of these sites would then be studied and if needed, traditional approaches could be used to attempt to find causal relationships.
Considering the two approaches, my opinion is that the second may prove more useful on these specific types of pollutants. This is because it seems more conducive to regulating these chemicals, as the approach would generate data from specific, problematic areas. Having said this, in the end, given sufficient resources the compound-specific approach to potential contaminants is the best route, as it could prevent large amounts of contaminants from entering the environment to begin with. In order to place most of our eggs in this more precautionary basket we must first change the way chemicals are introduced to the market. The only real way to do this is by taking back our Congress from the corporations and sufficiently funding our environmental regulatory agencies.
“Lessons from Endocrine Disruption and Their Application to Other Issues Concerning Trace Organics in the Aquatic Environment”