has a reputation as a female hormone, but while reproductive-age women have the highest levels, men also produce estrogen â about the same amount as non-reproductive women. The Pope himself contributes a small amount of oestrogen pollution.
Bizarrely, some industrial chemicals are similar enough to hormones to cause problems. These substances, known as xenoestrogens, are found in certain plastics, detergents, and pesticides. Some xenoestrogens mimic male hormones. Tributyltin, a substance that is applied to the surface of boats to prevent algal growth, makes some female shellfish develop a great big gonopodium. Which, as you may have guessed, is a shellfish penis.
Itâs not only our fellow animals that are at risk from endocrine disruption. Tests of sex hormones on plants have shownthat some species are vulnerable to the effects of oestrogens. The growth of alfalfa, for instance, is reduced by oestrogens, while both male hormones and progesterone increase the growth of wheat plants. Oestrogens, on the other hand, cause abnormal structural development in broad bean, tomato, wheat and lettuce plants.
While these effects occur at concentrations of hormones much higher than those currently found in the environment, there is some irony in the fact that our hormones are affecting plants. Most readers have probably heard about the benefits of soy products for menopausal women. Plants such as soy contain phytoestrogens, which are similar enough to human-produced oestrogens to relieve symptoms caused by falling oestrogen levels in the body.
However, current thinking is that plants do not produce these uncannily human hormones as a helpful, selfless hot-flush remedy. Rather, experiments on both mammals and birds have shown that phytoestrogens are plantsâ way of offering pesky herbivores a contraceptive-laced snack, as a way of keeping our numbers down. This was dramatically demonstrated in China during the 1930s and â40s, when regions of Jiangsu province switched to phytoestrogen-rich cottonseed oil as a staple food â and watched their birth rate drop to zero. It seems that eating large quantities of oestrogen really messes with male fertility.
The many illegal drugs derived from plants are also believed to be weapons in the vegetable kingdomâs passiveâaggressive arsenal. For example, the compounds in opium poppies may have evolved to make herbivores inclined to wander fearlessly into open spaces, where they can be picked off and eaten. That our species can currently indulge without being cleaned up by wolves may be a point for us on the great evolutionary scoreboard, but tests for illegal drugs in our waterways suggest plants may still have the last laugh.
Last year, Spanish scientists tested the water of the Llobregat River and found traces of cocaine and amphetamines. In 2008, tests of a Welsh waterway showed that the load of both these drugs skyrocketed in July, which suggests the locals may have been partying hard during their Northern Hemisphere summer. And just as being exposed to a cocktail of therapeutic drugs is unlikely to improve the health of aquatic animals, there is also reason to suspect that our mollusc and crustacean friends do not necessarily enjoy getting inadvertently wasted.
So far, it appears no one has tested for the effects of cocaine or amphetamines on aquatic animals, but it might be useful to consider a notorious experiment conducted by NASA in 1995. It seems that the brains at NASA, having already massively benefitted humankind by jabbing an American flag into the topsoil of the moon, decided it was time to do something even more useful. The obvious choice was to get hold of a lot of drugs and test them on spiders to see how this affected their ability to construct webs.
This experiment, apparently designed to see if spiders could be used in toxicity tests, was a repeat of a similar study done in the 1940s. It showed that animals could indeed be affected by our
Bizarrely, some industrial chemicals are similar enough to hormones to cause problems. These substances, known as xenoestrogens, are found in certain plastics, detergents, and pesticides. Some xenoestrogens mimic male hormones. Tributyltin, a substance that is applied to the surface of boats to prevent algal growth, makes some female shellfish develop a great big gonopodium. Which, as you may have guessed, is a shellfish penis.
Itâs not only our fellow animals that are at risk from endocrine disruption. Tests of sex hormones on plants have shownthat some species are vulnerable to the effects of oestrogens. The growth of alfalfa, for instance, is reduced by oestrogens, while both male hormones and progesterone increase the growth of wheat plants. Oestrogens, on the other hand, cause abnormal structural development in broad bean, tomato, wheat and lettuce plants.
While these effects occur at concentrations of hormones much higher than those currently found in the environment, there is some irony in the fact that our hormones are affecting plants. Most readers have probably heard about the benefits of soy products for menopausal women. Plants such as soy contain phytoestrogens, which are similar enough to human-produced oestrogens to relieve symptoms caused by falling oestrogen levels in the body.
However, current thinking is that plants do not produce these uncannily human hormones as a helpful, selfless hot-flush remedy. Rather, experiments on both mammals and birds have shown that phytoestrogens are plantsâ way of offering pesky herbivores a contraceptive-laced snack, as a way of keeping our numbers down. This was dramatically demonstrated in China during the 1930s and â40s, when regions of Jiangsu province switched to phytoestrogen-rich cottonseed oil as a staple food â and watched their birth rate drop to zero. It seems that eating large quantities of oestrogen really messes with male fertility.
The many illegal drugs derived from plants are also believed to be weapons in the vegetable kingdomâs passiveâaggressive arsenal. For example, the compounds in opium poppies may have evolved to make herbivores inclined to wander fearlessly into open spaces, where they can be picked off and eaten. That our species can currently indulge without being cleaned up by wolves may be a point for us on the great evolutionary scoreboard, but tests for illegal drugs in our waterways suggest plants may still have the last laugh.
Last year, Spanish scientists tested the water of the Llobregat River and found traces of cocaine and amphetamines. In 2008, tests of a Welsh waterway showed that the load of both these drugs skyrocketed in July, which suggests the locals may have been partying hard during their Northern Hemisphere summer. And just as being exposed to a cocktail of therapeutic drugs is unlikely to improve the health of aquatic animals, there is also reason to suspect that our mollusc and crustacean friends do not necessarily enjoy getting inadvertently wasted.
So far, it appears no one has tested for the effects of cocaine or amphetamines on aquatic animals, but it might be useful to consider a notorious experiment conducted by NASA in 1995. It seems that the brains at NASA, having already massively benefitted humankind by jabbing an American flag into the topsoil of the moon, decided it was time to do something even more useful. The obvious choice was to get hold of a lot of drugs and test them on spiders to see how this affected their ability to construct webs.
This experiment, apparently designed to see if spiders could be used in toxicity tests, was a repeat of a similar study done in the 1940s. It showed that animals could indeed be affected by our
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