Environmental contaminants, such as toxic heavy metals, pesticides, industrial chemicals, and particulate air pollutants, not only damage health and increase the risk for various diseases, such as cancer, it’s also speculated such contaminants may contribute to the development of Alzheimer’s disease (AD). A recent review explains how these contaminants are linked to the etiology of AD based on animal and epidemiological studies.
Currently without a cure, AD is a progressive and irreversible neurodegenerative disease. Difficulty in remembering newly-learned information is the most common early symptom for AD. The molecular mechanism for defective neurogenesis and synaptic pathology in AD is accumulation of beta-amyloid (Aβ) oligomers which form plaques in brain.
Here are some of the shocking numbers for AD within the U.S. in 2016:
Currently 5.1 million people suffer AD; the number will reach 13 million by 2050
Every 66 seconds, someone develops AD
AD is the number six leading cause of death and 1 in 3 seniors die with AD or other dementia
The cost for AD is $236 billion and is will rise to $1 trillion by 2050
Seventy percent of the AD risk is attributable to genetics; genes associated with early and late onset AD are reviewed. The other 30% comes from environmental factors. The following environmental contaminant groups may bring AD risk.
The metals that trigger the AD pathology include aluminum, arsenic, cadmium, cobalt, copper, iron, lead, manganese, mercury, selenium, and zinc. In my previous blog, I discussed the top 4 metals (arsenic, cadmium, lead, and mercury) which can cause severe health problems. Exposure to these toxic metals can lead to AD as well. Other metals such as iron, selenium, and zinc, which are required for normal body metabolism, can also increase AD risk when absorbed in excessive or insufficient quantities.
Pesticides from Agriculture
Since pesticides are often designed to target an insect’s nervous system, many of them are toxic to humans as well by negatively affecting neurochemical processes. Organophosphates, organochlorine, carbamates, fipronils, pyrethroids, and increasingly, neonicotinoids, may all play some role in AD pathology. Although regulatory authorities established rules and methods for pesticides analysis, with continual release of new pesticides, exposure continues to drive the risk of AD development.
Other Industrial Pollutants
Many other industrial contaminants are organic contaminants, including volatiles and semi-volatile organic compounds (VOCs and SVOCs). Some of them are regulated in drinking and wastewaters and are often analyzed by GC and GC-MS/MS techniques. Others have raised health concerns as they have now been detected in the environment while their potential long-term health effects remain unknown. These contaminants of emerging concern, or “emerging contaminants”, include Pharmaceutical and Personal Care Products (PPCPs), hormones and endocrine disruptors, flame retardants, and nanoparticles. Novel technologies such as Orbitrap-based LC-MS/MS or Orbitrap-based GC –MS/MS, or single nanoparticle ICP-MS (spICP-MS) are used to detect their presence and characterize them. Still, others, such as dioxins, are Persistent Organic Pollutants (POPs). They are hard to degrade once released into the environment and can be quantified by magnetic-sector high resolution mass spectrometry.
Although the effects of some of these chemicals related to the development of AD need more research to understand, animal or in vitro studies have shown that these chemicals may increase the risk for AD through the accumulation of Aβ oligomers which interrupt neurotransmitter function.
Air pollutants from industrial activities pose severe threat to public health by causing cardiovascular and respiratory diseases. In the U.S., six major air pollutants (O3, particulate matter, CO, NOx, SO2, and lead) are regulated with National Ambient Air Quality Standards to protect the public health, especially that of vulnerable population. In addition, VOCs and SVOCs also contribute to air pollution. To ensure safe air, air quality must be constantly monitored to meet regulatory compliance.
Animal and cellular studies indicate the above air pollutants accelerate Aβ peptide accumulation, which further lead to formation of Aβ peptide plaques. VOC exposure can cause the neurotransmitter imbalance and affect onset of AD. However, the epidemiological studies are still limited to make solid connections between air pollutants and etiology and progression of AD.
Protecting the Future
A variety of environmental contaminants can potentially lead to development of AD, although more research is necessary before a definitive conclusion can be made. It is time to watch what we eat, drink, and breathe, and appreciate why regulatory authorities require testing and analysis of harmful contaminants in state-certified laboratories. After all, our health makes a difference in the quality of our life. So remember to protect today to have a healthier future!