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Hormone Mimics

The following excerpt is from Chapter 8 of Roger Payne's book, Among Whales

"Many toxic compounds are highly soluble in fats but almost insoluble in seawater. For such compounds, the ocean acts not as a means of dissolving them down to harmless levels, but as a giant distribution system-a conveyor belt, so to speak-carrying them outward from the continents and depositing them in that ocean of fat collectively comprising the totality of fat droplets and fat deposits that are found in all living oceanic plants and animals.

"In comparison to the ocean of water, the ocean of fat is minuscule. It is therefore incapable of diluting down to harmless levels the fat-soluble toxic substances that humans have already manufactured and will soon have dumped into the environment.

I will focus on just one of these groups-the PCBs. They are particularly damaging to vertebrates that live at or near the top of food chains.

"The most important compounds with these characteristics are called "organohalogens." Many of these are highly toxic organic molecules that also contain one or more halogen atoms (fluorine, chlorine, bromine or iodine). They are widely used as pesticides, fungicides, herbicides, and insecticides-they are, in fact, biocides that are found in hundreds of products. We know them by names like DDT, DDE, Mirex, Aldrin, Endrin, Dieldrin, dioxins (of 75 forms), furans (of 135 forms), PCBs (polychlorinated biphenyls of 209 forms, of varying toxicity), PBBs (polybrominated biphenyls), hexachlorobenzene (HCB), benzo[a]pyrene (b[a]p), one of a large family of polyaromatic hydrocarbons (PAHs), Agent Orange etc. Most organohalogens are no longer produced intentionally, but many arise as accidental by-products of improper burning or in manufacturing processes using chlorine. Some are also contaminants found in chlorinated pesticides. As a practical matter, organohalogens are unintentionally produced in such things as combustion of fossil fuels as well as wood (including forest trees during forest fires), in the production of paper (while it is pulp), and in waste incineration, including the burning of tires. Organohalogens have thousands of uses and are universal in their occurrence.

"I will focus on just one of these groups-the PCBs. They are particularly damaging to vertebrates that live at or near the top of food chains where bioaccumulation causes an increase in concentration of any substance that cannot be excreted by animals. I am referring to a process that concerns food pyramids (also known as "food chains" or "food webs").

With each new level of predator there is a further multiplication of the concentration of PCBs by about ten times.

"Diatoms are the smallest plants in the ocean. They are also the most numerous and constitute as well the greatest total biomass of any plants on earth. All life in the oceans, from the tiniest planktonic animals to the largest whales, is absolutely dependent on diatoms to trap energy from the sun. Diatoms are single cells encased in silica shells. Silica is basically sand and so these outer shells are really constructed of what we think of as stone. Diatoms would sink like stones and end up in the dark depths of the ocean out of the light they need to nourish them if they didn't have something to prevent this from happening and to keep them up near the sunlight where they can trap its energy. The thing they use for flotation is a tiny droplet of oil. (All plants, even single-celled oceanic plants, contain fats and oils.)

"Let us consider the consequences of that tiny drop of oil: when substances like PCBs enter seawater, they are so nearly insoluble that their concentrations can only be measured in parts per trillion, that is, parts per thousand, thousand million. But when any molecule of, say, a PCB touches the droplet of oil in a diatom, it will immediately go into solution in that oil-that is, in the diatom. Because the diatom has no way to break down the PCB molecule, it just stores it. Diatoms have fierce microscopic predators, and as a general rule these predators must consume at least ten diatoms before they can divide their cells to reproduce themselves. But the predators can't digest PCBs either, and the result is that each predator ends up with about ten times as many PCBs as there were in each diatom it preyed upon.

The government forbids the sale of any food containing more than two parts per million of PCBs ... the tissues of killer whales have revealed PCBs in concentrations of four hundred parts per million

"The same process repeats itself with each level of slightly larger predator that feeds on prey smaller than itself, and with each new level of predator there is a further multiplication of the concentration of PCBs by about ten times. Whales feed on prey that live between the second and seventh levels of the food chain. This means that the concentration of PCBs they take into their bodies with each meal is between 102 and 107. The highest concentrations (107) represent a concentration of toxic substances ten million times higher than those in the ocean through which the whale is swimming. In fact, scientists have measured levels of PCBs in fish more than twenty-five million times higher than the levels of PCBs in the sea around them. When you take something that is measured in a single part per trillion and concentrate it ten million times, its concentration becomes ten parts per million. With substances as toxic as some PCBs, ten parts per million can be a very dangerous level.

"For example, in the United States the federal government forbids the sale of any food containing more than two parts per million of PCBs. The law also states that anything containing fifty parts per million of PCBs has to be disposed of in sealed, marked containers at special facilities in which they can be incinerated at high temperatures into harmless components.

"Recent analyses of the tissues of killer whales caught in mid-ocean (i.e., far from any local sources of industrial wastes where they might be getting above-normal concentrations of PCBs) have revealed PCBs in concentrations of four hundred parts per million, while there are also records of beluga whales from the gulf of St. Lawrence with concentrations as high as thirty-two hundred parts per million.

Because humans also live at the top of the food pyramids in the sea, people and whales are the animals most at risk from PCBs

"But let us now go to Cape Cod, that part of the United States coastal waters so much like Peninsula Valdés. Recently there was a bottle-nosed dolphin from that area whose tissues were analyzed and shown to contained sixty-eight hundred parts per million of PCBs, a concentration 3400 times what the federal government considers safe to sell, and 136 times higher than the level that would designate it as toxic waste. This animal was, by definition, a swimming toxic waste dump. (By the way, the same species of dolphin also occurs in the waters of Golfos San José, and Nuevo.)

"Because humans also live at the top of the food pyramids in the sea, people and whales are the animals most at risk from PCBs.

"In spite of the high levels of PCBs that have already been found in whales and porpoises, there is no direct evidence about what constitutes a lethal dose of PCBs for any marine mammal. However, there is excellent evidence that one of the general effects of PCBs on mammals and birds is to diminish the ability of their immune systems to fight infection.

There is excellent evidence that one of the effects of PCBs on mammals and birds is to diminish the ability of their immune systems to fight infection.
"In the western North Atlantic about half of the population of bottle-nosed dolphins and 10 percent of the feeding population of humpback whales died in 1988 from what was declared to be an organism similar to red tide. Although they have not yet made their suspicions public, two of the scientists involved in the autopsies of these animals told me that they believed the porpoises probably died from having their immune systems suppressed by pollutants. Since these cetacean species have coexisted for a very long time with the same pathogens that killed them, one wonders why so many suddenly succumbed to these pathogens.

"There was recently a die-off of seals in Northern Europe that is also suspicious in this regard. Although it was clearly established that the die-off was caused by well known viruses (related to canine Distemper and human measles) seals too have presumably undergone their entire evolution in co-existence with these diseases. There is growing concern now that these outbreaks could have been the result of damage to the immune systems of these marine mammals, possibly from the accumulation of such toxic substances as PCBs, PBBs, etc. If the current indications are borne out by further research — that these and other toxic substances indeed have a deleterious effect on cetacean immune systems (as they are known to have for other vertebrates) — then one can conclude that marine mammals are being affected by a condition strikingly similar to AIDS as regards its effects on its victims' immune systems.

"The AIDS virus is, of course, harmless in itself. No one has ever died of the HIV virus, which causes aids. What kills HIV patients is some other pathogen that they are unable to survive owing to the fact that their immune systems have been compromised by the HIV virus. If toxic substances are indeed damaging vertebrate immune systems, then they are affecting life in the oceans in the same way that AIDS affects its human victims, and it is not unreasonable to conclude that the oceans themselves have the functional equivalent of AIDS.

One can conclude that marine mammals are being affected by a condition strikingly similar to AIDS as regards its effects on its victims' immune systems.

"What we have been discussing is the effect of increased concentrations of PCBs achieved, for the most part, by bioamplification as we move up the food chain. There is, however, another mechanism of bioamplification that has not been generally recognized. It only occurs in mammals, and it depends on the fact that when a mother mammal nurses her first young, she also passes to her baby, dissolved in her milk, her lifetime accumulation of those toxic substances that are soluble in fat but relatively insoluble in water. The result of this is that her baby does not start out with a clean slate but with roughly its mother's concentration of PCBs. If the baby is a female, she will, when she matures and has a baby of her own, pass on in her milk an even higher concentration of toxic substances. This toxic load will consist of the substances that the baby who is now a mother collected in the meals that she obtained for herself plus whatever she received from her mother in her mother's milk. The result of this is that as long as we are dealing with substances that persist in an animal's body longer than the intergeneration time, there will be an accumulation of toxic substances from one generation to the next. As far as is presently known, PCBs seem to fit this pattern. If future evidence continues to support this conclusion, then whales, dolphins, porpoises, seals, sea lions, sea otters, and polar bears may all be doomed to extinction. Of course, human beings would face a similar threat were it not for the fact that we can easily sidestep this danger of passing fat-soluble pollutants to our offspring simply by feeding our babies formula instead of breast milk.

If future evidence continues to support this conclusion, then whales, dolphins, porpoises, seals, sea lions, sea otters, and polar bears may all be doomed to extinction.

"Regardless of whether a solid correlation is made between PCBs and damage to vertebrate immune systems, there is one prediction that can be made regarding the damage that these substances may cause for humanity if they continue to increase in concentration in the seas.

"Of the roughly 1.2 million tons of PCBs that were manufactured before their production was halted, about 15 percent were sold to developing nations, mostly as coolants contained in the transformers of power company substations. The proper disposal of these coolants, once the transformers burn out in the normal course of daily use, involves an expense that most developing nations cannot be expected to sustain, given their other priorities. However, if the PCBs in the power company transformers are not disposed of properly, many of them will eventually reach the oceans, and it has been predicted that when they do so, the concentration of PCBs in commercially valuable oceanic fish will rise to levels at which they will no longer be saleable (i.e., above two parts per million). There are no additional steps we must take in order to have this dire prediction fulfill itself. All we have to do to achieve this disaster is to do nothing, to take no steps to collect the PCBs in these transformers and dispose of them properly.

"If we fail to act, the only way out of this predicament in the future may well be to decide that two parts per million of PCBs is too low a measure of toxicity and that in fact it is okay to consume fish with a higher concentration than that. Lest we think that this kind of scenario is unreasonable, we need only realize that it is made with the assumption that all the remaining PCBs scattered around the developed world will be disposed of properly so that just the 15 percent originally sold to developing nations is at issue-a most unrealistic assumption. It is also well to point out that in Lake Ontario, one of the Great Lakes of the United States, the largest freshwater lakes in the world, there is no longer any significant commercial fishery for trout. The reason commercial fishing has ceased here is because the concentrations of toxic substances in commercially valuable trout are too high to allow them to be sold.

 
 
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