A variety of chemicals have been demonstrated to have effects on hormone systems in animals and humans. Some of the adverse effects observed in animals, and to a lesser extent in humans include:
-Reproductive Effects/Birth Defects
Some of these chemicals are used in plastics, food production and packaging, paints, pesticides, cosmetics, pharmaceuticals, detergents, wetting agents, furniture and carpets. Others are produced as byproducts of pulp and paper production, incineration, fuel combustion in vehicles, and animal production. There are a variety of naturally produced phytochemicals in foods including soybeans, legumes, flax, yams, and clover. Humans and animals also produce hormones naturally and by taking pharmaceuticals such as birth control bills and hormone replacement therapy, which can flow into sewage treatment and drinking water systems
The science is still evolving to quantify the effects of suspected hormone related chemicals. Are they harmful? Do they produce adverse effects, and if so at what levels? In some cases these chemicals do cause effects, but it is unclear that these are adverse or harmful effects. In other cases it appears that a human or animal needs to be exposed to an extremely high dose that they are not likely to encounter in a lifetime.
The age of the exposed human or animal is also critical. Unborn fetuses and infants are the most susceptible. Environmental hormones may also play a role in exacerbating hormone related cancers of the prostate and breasts.
Another concern lies in the effects of bioaccumulation of one or multiple chemicals within the body. Even though lifetime exposure may be low, bioaccumulation could result in concentrations enough high enough to have an effect.
Many chemicals may interact to produce additive effects. Even though exposure to any one chemical is relatively small, we are exposed to complicated mixtures of many hormone-modulating chemicals throughout our lives, which together have the potential for creating an adverse effect.
Many governments around the world, particularly in Japan, the United States, and Europe have started to study this question from a regulatory perspective. If a chemical is determined to have a hormone related effect, it is unclear what steps, if any will be taken to control and regulate it. But the mere study of this question could end up costing industry over $75 billion dollars by some estimates.
The United States assembled the Endocrine Disrupter Screening and Testing Advisory Committee (EDSTAC) which later evolved into the Endocrine Disruptor Methods Validation Subcommittee to develop a set of assays to quantify the effects of chemicals on estrogen, testosterone, and thyroid related hormone systems called the Endocrine Disruptors Screening and Testing Program. By some estimates it could cost anywhere from $1 to $1.5 million to completely test each of the approximately 75,000 chemicals covered by the Toxics Substances Control Act, resulting in a total bill of $75-$110 billion, and that is just for the first phase of testing.
There are also other chemicals not covered by the act such as metals and cleaning products, which may be tested as well. The EPA is currently proposing to start with about 1500 chemicals used in pesticides or produced in high volume, but plans for the other chemicals have not been established.
Another key question is whether or not to test the breakdown products of chemicals, which in some cases have stronger effects and can be more persistent and bio-accumulative than the original chemical. Will a company have to perform 20 tests for the breakdown products of a single chemical?
Who is going to pay the bill for this potentially incredibly costly project? Will a company be able to waive testing for a chemical if it can show that environmental and human exposure is minimal or non-existent? How long will this testing process be stretched out over? Does it represent a major long-term growth opportunity for testing laboratories, and equipment and lab animal vendors, or just a short-term blip in revenues?
By some estimates, up to 1200 animals will be slaughtered for each chemical completely tested for hormone modulating effects. The complete testing of all chemicals included within the Toxics Substances Control Act could ultimately result in the slaughter of 96 million animals.
Concern over this massive loss of life have provoked animal activist groups to propose that the EPA find alternatives to animal testing, such as the use of single cell assays like the E-Screen, or computer modeling techniques like Quantitative Structure-Activity Relationships. Animal rights advocates have already succeeded in reorganizing the US effort to develop an endocrine disruptor testing process for chemicals, and by some estimates have set the process for developing a screening and testing program back by two years.
Other environmental activists have argued that if we dont test on animals, we will be de facto testing these chemicals on billions of humans instead. They are concerned that these assay and modeling techniques only look at a single class of endocrine disrupting chemicals that operate directly on a hormone receptor. In some cases, such as with DEHP, chemicals can operate through other pathways to interfere with the breakdown or production of hormones, and these types of chemicals would not be detected by E-Screen types of assays or QSAR modeling.
There is some concern that the waste produced by CAFOs contains environmentally relevant doses of natural and pharmaceutically produced hormones. One concern is the various pharmaceuticals administered to maximize animal growth and health including growth hormones, antibiotics, and other chemicals. Another issue is that pregnant animals naturally produce incredibly high levels of estrogens.
Another concern is that these hormone related chemicals could be stored in manure, which is later spread on fields. Is the run-off from fields treated with this manure a concern? Are there methods that can be used to reduce or eliminate the hormones from these manures?
Researchers have also discovered that environmental hormones can adversely affect the production of nitrogen by plant rhizobium. Can hormones left in the manure reduce the natural process of nitrogen fixation, and hence increase the need for applied fertilizers?
Some chemicals used in paints such as tributyltin have been show to have hormone-modulating effects in wildlife, such as snails. The use of tributyltin in one of the new Euro notes has even sparked a lawsuit by an individual who claims adverse effects on sexual function.
Activist groups have taken up the cause against some of the chemicals and have proposed alternatives. The International Maritime Organization has also proposed to phase out tributyltin.
A variety of brominated flame-retardants are widely used in furniture, carpet, and electronic products manufacture. These substances are increasingly being detected in marine environments, human breast milk, fatty tissue, and blood. Although no acute health risk has been identified, the Danish EPA is concerned with the long-term implications for fetal development and cancer.
The EU has already called for a ban on one of the most hazardous forms of the substances, penta BDE, beginning in 2003. This ban will expand to other members of the brominated flame retardant family in 2008. At the moment, there are no bans or restrictions on the use of these substances in the US. However, activist groups are starting to lobby for the use of alternatives.
Bisphenol-A is widely used in a resin lining inside most food and beverage cans. Although it has been demonstrated to create hormone related effects at high doses, there is an active debate as to whether these effects are toxicologically relevant. Researchers have also found that bisphenol-A can become more bioaccumulative when combined with chlorine.
A few researchers have noted bisphenol-A effects at extremely low doses, which would be environmentally relevant. However, other researchers have had difficulty repeating these experiments
Phthalates are widely used as a plasticizer to soften up otherwise hard plastics. There is concern that the use of phthalates such as DINP and DEHP could affect humans, particularly if used in toys for small children or in medical equipment, although many researchers have concluded that human exposure to phthalates is not environmentally relevant. Several bans have already been initiated in Europe on some phthalates in childrens toys, and the FDA is considering regulating the use of some phthalates in some types of medical devices in the US.
A number of pesticides have been demonstrated to have effects on estrogen and testosterone related hormone systems. There is some concern that the wide use of pesticides could affect humans and animals. Pesticides are one of the first categories of chemicals being proposed for testing for endocrine disruptor effects by the EPAs Endocrine Disruptor Methods Validation Subcommittee.
Alkylphenols and their Ethoxylates are widely used in liquid detergents and as wetting agents in a variety of industrial and consumer applications. There is concern that these chemicals and their breakdown products can produce hormone-modulating effects. It is not clear if any of these are adverse effects or if they are occurring in high enough quantities to create a need for concern.
A variety of man-made and natural combustion processes can produce suspected endocrine disrupting chemicals such as dioxins and furans. Some of these processes include incinerators, internal combustion engines, back yard trash burning, candles and incense, forest fires, and structural fires. While some of these processes, such as incinerators are fairly easy to regulate and control, others by their very nature are difficult or impossible to control. Considerable research is being conducted by the EPA and other researchers to determine where these chemicals are accumulating, the levels of suspected endocrine disruptor chemical being emitted by various sources, and what kind of control technologies are effective in reducing or eliminating their emission into the environment. The European Union has recently enacted tight controls on the presence of dioxins in food and animal feed.
There is evidence of Endocrine Disrupting Chemical effects on invertebrates, fish, frogs, reptiles, birds, and mammals and that seeing these effects in animals might foreshadow some of the potential effects on humans. EDCs have been suspected in causing:
-Hermaphroditism in gastropods
A variety of naturally occurring hormone modulating chemicals are found in soybeans, legumes, clover, flax, yams, and others. Researchers have been reaching mixed conclusions as to the benefit and/or toxicity of these plants as regards to their hormone related effects. While in some cases they seem to reduce or the incidence of hormone related adverse effects, in other cases they have the opposite effect.
There is a concern that some of the chemicals used in food packaging such as cans and plastic containers may have hormone-modulating effects. It is not clear if humans are exposed to toxicologically relevant doses. Considerable research is going on in this area. So far little regulation has been passed on the use of suspected or confirmed endocrine disruptor chemicals in food packages. However, Japan has proposed banning the use of vinyl gloves in food service kitchens because of concern that di-2 ethyl hexyl phthalate (DEHP) can leach into food from the gloves.
In addition to drugs designed for their hormone modulating effects such as birth control pills and hormone replacement therapy, there is concern that other pharmaceuticals could have hormone related effects on humans. These could lead to higher levels of hormone like chemicals in the urine and feces, which flow into sewage treatment systems. Since our current sewage treatment systems are not designed to break down hormones, there is a concern that they could flow into the environment at large.
A variety of chemicals used in dental sealants, skin lotions, and makeup are suspected of causing endocrine disruptor effects. Some of the chemicals of concern include bisphenol-A, hemp, paraben, and the ultraviolet sunscreens Bp3, 4-MBC, OMC, ODPABA, and HMS. There is some concern as to whether cosmetics should be regulated based on hormone related effects rather than the traditional toxicological metrics.
A number of researchers have reported that relatively low doses of chemicals such as Bisphenol-A and some phthalates produced hormone related effects in animals. They noticed that at low doses, the effects seem to create an inverted U-shaped curve, where smaller doses created a greater effect, along the same lines as homeopathic theory. However, other researchers have had great difficulty in repeating these results, which has led to a debate over whether these effects are real, or are just some artifact of another variable such as feed, animal strain, light exposure, leftover chemicals in the cages, or music.
If these effects can be confirmed, it might ignite a fire under the whole debate over how to regulate hormone-modulating chemicals. Government regulators might consider banning or regulating chemicals that produce a hormone-modulating effect even if traditional toxicological studies indicate that humans are not exposed to relevant levels.
A variety of suspected and confirmed hormone modulating chemicals enter our drinking water and wastewater treatment systems from factories, farms, pharmaceuticals, and natural biological processes. At the moment, few water treatment plants have the capacity for eliminating or greatly reducing these chemicals from the water. However, researchers are busy studying a variety of techniques that might prove effective in doing so at a reasonable cost. Ammonia Perchlorate recently became the first chemical proposed to have a maximum concentration level based on an endocrine disrupting effect.
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