Contaminants and Cell Function

June 14, 2017

As water becomes an increasingly scarce resource, more of it is being recycled and reused. Regulation and policies to protect human and environmental health are of ever-greater importance.  Dr. Edo McGowan has forty years of experience in the development of local, regional, and international programs relating to health aspects of water quality, vector control, the analyses and disposal of hazardous materials.  Here he offers his perspectives on the potential effects of contaminants of emerging concern (CECs) on human mitochondria.

Dr. McGowan earned his degree in medicine from the Keck School of Medicine at USC, a doctorate in water quality and water policy from Cal Western, and an MSc in political science. He wrote his dissertation on water quality issues facing Ventura County while simultaneously rewriting its major Regional Water Quality Control Plan as the county’s water quality planner.

Dr. McGowan has conducted environmental review of national toxicants disposal in The Sudan and Somalia for USAID and initiated the national toxic materials monitoring system for Ethiopia as consultant to the World Bank. He has participated in numerous advisory panels to the National Academies NRC, Library of Congress, EPA, and the UN.

We’re pleased to share his insight here.

While water purification and reuse practices are beneficial advancements, it’s important to recognize that further study and regulation are critical to understanding the long-term effects of contaminants not removed by current treatment technologies.

Can today’s water quality standards keep up with the input of emerging contaminants? The EPA, by way of the Toxic Substances Control Act (TSCA), estimated an addition of somewhere between 500 and 600 new chemicals per year. What might be the range of potential impacts to the human metabolic processes? Is the regulatory community following this?

To look at this general policy area, I’d like to single out just one of the many metabolic systems that might be affected by uncontrolled emerging contaminants. Of interest because of its critical metabolic functions, we will look at the mitochondria.

Mitochondria are numerous small organelles whose size ranges between 0.75 and 3.0 um. They reside within cells, move around, and can fuse together. Their number varies with the type of cell and the cell’s need for energy. For example, a liver cell, which is cubical in shape, having sides of 20 to 30 um may contain over 2000 mitochondria.

Mitochondria are scripted to the job of being the main generators of power that drives cellular machinery and processes. How this power is used and generated requires a delicate cross-talk between the two sets of DNA residing within the cell. For mitochondria, its generation of power is but one of many important functions. Mitochondria also control apoptosisprogrammed cell death.

Many body parts need continuous replacement and to be refreshed, old cells need to be removed, thus they need to die. But death needs to be carefully orchestrated and this is one of the mitochondrial functions. Other cells, however, need to stay vital and some are designed to last for the owner’s entire lifetime. These long-lived cells need their own carefully orchestrated systems, which if disrupted by contaminants of emerging concern (CECs), see developing pathologies.

Additionally, mitochondria are involved with the status of cellular and tissue calcium levels and hence calcium’s control over signaling. Delicately controlled calcium levels within various cell and tissue compartments act as switches to turn on or off cellular functions, and for cross-talk with components.

Mitochondria are specialized, and one size does not fit all. Mitochondria of the brain would differ from, say the liver or heart and there would thus, be differences in sensitivity to toxins. Even in the brain, different tissues will have different mitochondria. Thus, how CECs impact mitochondria is a highly specialized and uniquely singular issue. When it comes to a discussion of impacts from CECs, it is fairly easy to see that damaged mitochondria may underlie a vast array of human ailments and disease.

Chronic exposure to toxins and pathogens may shift these little organelles toward an unhealthy state. Their dependent end organs then begin to operate less well and we may see development of longer-term chronic, autoimmune, or neoplastic pathologies. This decline may also be seen in the mitochondria of the capillary endothelial cells serving the end organ, where end organ might be heart, brain, kidney, etc.

Inflammatory response in the capillary may cause fluid leakage into adjacent interstitial tissues with a consequent widening of inflammatory responses. This creates a series of feedback loops and thus creates within the capillary a layering of scar tissue. Diameter is narrowed and roughened. The flow is reduced and the tissues get less oxygen, hence reduction of end organ function.

This discussion is driven by the findings of toxic materials and serious pathogens or their genes within finished and disinfected Title 22 California recycled water that is now being used to irrigate certain crops. Can and do those toxic materials or pathogens impact the mitochondria? These are critical questions to investigate. 

Bacteria are just part of the issue. Many toxins are found in the finished recycled water. And mitochondria are particularly susceptible to damage by a combination of pathogens and toxins.

Organic micro-pollutants (OMPs) such as pharmaceuticals are persistent pollutants that are only partially degraded in waste water treatment plants. Treatment train design impacts the availability of bacterial endotoxins. Advanced water treatment and the use of activated carbon seemed to up-shift final endotoxin.

Since pharmaceuticals can and do impact mitochondria, this, by itself, is an issue. The wastewater stream is seen as a growing issue as many toxicants fail to be adequately removed.  Do these contaminants bioaccumulate in crops? What may happen when those crops are consumed?  

Some pathogens, particularly viruses can and do pass through typical screens in treatment trains used in the production of Title 22 recycled water. Many of these detractors are not considered by the regulatory standards or the regulatory community. The current standards used for ascertaining the quality of this water are antiquated. The end result is a potential increased risk to public health.

The use of this water for irrigating crops consumed raw, such as the salad crops, may see these toxic materials or pathogens bioaccumulate in the edible portions of such crops. Any student of phyto-remediation is well acquainted with these issues. Unfortunately, there are few if any standards addressing potential bioaccumulation levels in crops.

As the State of California and other areas in the nation rely more heavily on recycled water as an off-set to potable supplies, the contained and in many cases unregulated contaminants may represent a growing risk to public health.

We invite you to share your opinions and comments below.

What are your thoughts? Do you feel that the current water quality standards require updating?

About the Author

Dr. Edo McGowan

Dr. Edo McGowan has forty years of experience in the development of local, regional, and international programs relating to health aspects of water quality, vector control, the analyses and disposal of hazardous materials.

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