By Sara Wright
Endocrine disruption (ED) has been present in scientific literature for decades, but has not coalesced into a coherent topic in the popular media. This is down to several reasons: the issue is complex, its long-term ramifications remain unclear, and the path of mitigation is not well defined.
The US EPA defines an endocrine-disrupting compound as “an exogenous agent that interferes with synthesis, secretion, transport, metabolism, binding action, or elimination of natural blood-borne hormones that are present in the body and are responsible for homeostasis, reproduction, and developmental process.” EDs are heterogeneous and include synthetic chemicals that are widely used as industrial solvents and lubricants, agricultural chemicals and pharmaceutical compounds. Not only do they have serious impacts independently, but evidence is strengthening that the combined effect of multiple EDs can be exponentially harmful to the human body and ecosystems.
Some EDs were identified long ago as being responsible for the near extinction of entire species, such as the pesticide DDT and the bald eagle population. Others are only now being identified, especially as their multiple vectors of interaction with other substances emerge. Nearly all plastics that consumers use daily contain ED compounds. The majority of people in developed countries have a shockingly high “body burden”, which indicates synthetic compound levels carried in the blood and tissues. This was not true a mere generation ago.
Even infinitesimally low levels of exposure can cause abnormalities, especially if exposure occurs during a critical developmental window. Surprisingly, low doses may sometimes exert more potent effects than higher doses. EDs can affect not only the exposed individual, but also subsequent generations. Given that some of the most prevalent EDs have emerged from industrial chemistry, a relatively new field, the effects are likely not yet to have fully manifested.
But there are alarming signs everywhere. Water animals are exhibiting bizarre deformities, often in their sexual organs. In polluted lakes, amphibians are sprouting extra legs and alligators are developing stunted genitals. In the US Potomac watershed, male smallmouth bass were recently discovered to be transforming into “intersex fish” that display female characteristics – 80% were producing eggs!
There are similar signs in the human population. A startling trend shows significant increases in the numbers of genital deformities among newborn boys. The daughters of women exposed to DES – an ED drug prescribed from the 1930s to 1970s to prevent miscarriage – seemed fine at birth, but exhibited abnormally high prevalence of misshaped sexual organs and cancer later in life. New research has also tied EDs to obesity, insulin resistance and diabetes. Examples abound, and they paint a sombre picture.
Governments are moving toward regulating these substances. If the evidence continues to grow, and frogs in a lake are our modern-day canaries in a coal mine, EDs will become as important as climate change, and perhaps even more difficult to rein in. Nearly all industries will be affected, both by legislation to reduce the use of EDs, and by litigation seeking restitution for the damage they caused. Companies that seek to mitigate effects and produce safer alternatives will benefit in the long run.
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