Examples of Endocrine Disruptor Effects and Affected Species

Central nervous system (cognitive, mental, behavioral development) 

Hormones control many aspects of our lives, ranging from the fight or flight reaction of adrenaline to digesting sugars (e.g., insulin). Some hormones affect our reproductive systems these hormones were first identified in nature as endocrine disrupters. Because they affect so many of our processes, it is not surprising that their toxic effects can be very diverse. 

One reason why endocrine disrupter effects are cause for concern is the extreme potency of hormones. Hormones are effective in our bodies at levels as low cis 1 part per quadrillion (23 zeroes followed by a 1). They au e extremely short-lived this is one reason they are potent. Our bodies are designed to respond quickly to these chemicals at very low levels. 

Environmental chemicals are not as potent as our own hormones, but they act by interfering in some way with our natural hormones. This interference can lead to differences in response to the hormone by the body. For example, a lake in Florida where DDT had been spilled several years before was found to contain no repro-ductively capable male crocodiles. The males had decreased levels of testosterone, had smaller gonads, and were unable to successfully breed. The females had higher levels of estrogens than at other locations. Crocodiles do not have sex chromosomes (e.g., X and y chromosomes). Instead, sexual differentiation is dependent on the temperature of the surrounding sediment. In the presence of other chemicals that can mimic hormonal action (e.g., estrogen), this sexual differentiation process can be altered or affected, leading to the types of males and females identified at this lake. 

---

Table 11.2. Examples of Endocrine Disruptor Effects and Affected Species... 

---