And yet synthetic chemical use continues to increase worldwide. From 1940 to 1982, production of synthetic materials increased roughly 350 times. US production of synthetic organic compounds was approximately 435 billion pounds, or 200 billion kilograms, in 1992. Global production is estimated to be four times greater - about 1700 billion pounds, or about 800 billion kilograms, per year. While pesticide use is highest in North America and Europe today, pesticide use is expected to increase at a greater rate in developing countries in the near future.
Hormones play a key role in development, and especially sexual differentiation.
In mice, elephants, whales, humans, and in all other mammals, as well as in birds, reptiles, amphibians, and fish, the process that creates two sexes from initially unisex embryos is guided by these chemical messengers. In this central drama in which boys become boys and girls become girls, hormones have the starring role. Consequently, endocrine disruption may endanger populations because their immune systems are not functioning well and they cannot recover from infections. Or their ability to obtain sufficient food or avoid predators could be affected. There is also evidence that endocrine disruptors cause the loss of parenting instinct in some bird species.