Source: Water Matters
A 2008 study from the University of Calgary indicates that the sex of fish have changed as a result of endocrine disruptors found in the Oldman and Bow River water supplies. These findings raise the question: If these chemicals can change the sex of fish, what effects can they have on you and the water you drink? As Albertans increase their water literacy, many are asking questions about impact of endocrine disruptors on human health.
What are Endocrine disruptors?
Endocrine disrupting chemicals (EDCs) interfere with hormones. In both humans and animals, the endocrine system uses hormones from different glands, such as hypothalamus, thyroid, adrenal glands, for growth, development, reproduction, neurological processes, and immune functions. Endocrine disruptors mimic natural hormones like estrogen or testosterone or block the reception of hormones to other cells affecting how hormones are made or received.
Found in many of the products people use everyday such as pharmaceutical drugs, plastics, cosmetics, detergents, and pesticides, endocrine disruptors often emerge in municipal wastewater supplies. There are roughly five categories of EDCs: hazardous chemicals known as PCBs (polychlorinated biphenyls), pharmaceutical drugs, products associated with plastic, pesticides, and heavy metals.
The common use of endocrine disrupting chemicals is mirrored by their prevalent movement through our environment. For example, many pharmaceutical drugs that exit a person’s body end up in the municipal wastewater system. Detergent used for washing clothes also drain into the same system. Meanwhile endocrine disruptors can be transported through run-off from lawns, farmland or feedlots and industrial wastewater. The failure of wastewater treatment facilities to filter out EDCs leave them free to interact with fish, human and other organisms that may ingest them downstream.
EDCs and Ecosystems – Implications for wildlife and people.
Pesticides are a common source of endocrine disruptors. A 2005 Alberta Environment study found pesticides are common and widespread in Alberta’s surface water (rivers, lakes, streams, irrigation canals and returns, and urban streams). The study found 44 different types of pesticides in 65% of the samples at 326 locations, mostly located in the agricultural areas of Alberta. The effects documented of pesticides on the endocrine systems of frogs and amphibians included inhibited growth and changed reproductive organs even under low doses.
[*Agricultural runoff of pesticides has been linked to various reproductive issues in fish.]
The University of Calgary study, the result of a collaborative work between several universities, found EDCs in the Oldman and Bow Rivers. According to the study, EDCs from multiple sources including municipal wastewater and agricultural runoff was found to negatively impact the Longnose Dace, a small fish that grows to about six inches. Both rivers showed unusual sex ratios resulting in high numbers of females at downstream testing sites, most influenced by agricultural and municipal wastewater. Ninety percent of the fish along the Oldman River were found to be female, and 60% of the fish were found to be female along the Bow River. Other research on the Oldman River indicates that the potency of EDCs can increase up to approximately 400 times when present in combination with other environmental contaminants or EDCs. While the EDC potency could explain different sex ratios in fish, it also raises questions about the impact of these same EDCs to human health.
Risks to people
The risks associated with pesticides, a prevalent endocrine disruptor, are substantial. Pesticides risks to human health include:
* increased risk of cancer (e.g. non-Hodgkin’s lymphoma, childhood leukemia, and breast cancer)
* neurological impairment (e.g. Parkinson’s disease, Alzheimer’s disease)
* developmental effects (e.g. autism)
* reproductive effects (e.g. sperm abnormalities, birth defects)
* organ damage
* interference with the human hormone system
Regulating EDCs for human health – a complicated debate
The debate over EDCs and their impact on human health is the subject of much debate. The fundamental question is: What maximum allowable concentration (MAC) of an EDC can be considered safe for people and the environment? Maximum allowable concentrations (MACs) are limits set to define safe levels of exposure to chemicals like EDCs.
Answers vary depending by type of EDC and jurisdictions. Some evidence suggests very conservative MACs may be appropriate. For instance a 2007 United States expert panel commissioned by several health institutes concluded low-doses of endocrine disruptors like bisphenol-A (BPA) can have an impact on human health. BPA is an agent used to harden common plastics such as those used make plastic reusable water bottles. BPA is known to cause abnormalities in reproductive health, neurobehavioral (like hyperactivity disorder and autism), obesity, and type-2 diabetes.
EDCs such as pesticides are also highly debated in Canada. In particular, the herbicide 2,4-D used to control weeds in cereal crops, lawns, turfs, and pastures is prevalent in Southern Alberta’s basins according to Alberta Environment. While it is considered safe to use by Health Canada (2009), more recent evidence suggests 2,4-D in combination with other pesticides can affect neurological function, reproduction, immune systems, kidney function and the growth and development of children. In 2004, the Ontario College of Family Physicians advised Canadians to limit their exposure to pesticides including 2,4-D, until there is more conclusive research. Internationally, Europe and Australia have set guidelines for MACs that are much more conservative than Canada’s guidelines. Some estimates indicate Canadians can be exposed up to 1000 times more 2,4-D than Australians and Europeans (Boyd 2006).
By and large, research on endocrine disruptors and their effects on human health is still in its infancy. For example, there is little understanding of the risks associated with EDCs in combination with other EDCs or chemicals. Until more data is collected about the cumulative effects of EDCs on both people and ecosystems, a precautionary approach is warranted.