Organophosphates and organochlorines: toxic pesticides in use around us

Pesticides touch many different parts of our lives.  There are pesticides that homeowners apply around their homes to kill insects and rodents.  There are pesticides that farmers use to keep their crops from being devoured by insects and microbes.  Pesticides are also used on crops such as cotton, which are made into clothing.   Two classes of pesticides, organophosphates and organochlorines, were developed in the 20th century with broad application potential.  

Source: Classification of pesticides according to chemical composition

Organophosphates (OPPs) were originally developed as nerve-gas agents for chemical warfare. They work by paralyzing muscles, and in large amounts they can kill humans and other species in the same way that they kill bugs.  (Organophosphate Pesticides)   They stop a key enzyme in the nervous system called cholinesterase from working, and this can make people ill.  (Organophosphates)  Cholinesterase (acetyl cholinesterase) is an enzyme that removes the chemical neurotransmitter acetylcholine from the junctions between nerve cells.  OPP exposure also causes respiratory malfunction and infertility. OPPs are mutagenic and also cause cancer.  in Asia, the death caused by organophosphate pesticide poisoning is higher than that caused by common diseases because of the ever-increasing usage of OPPs in the agricultural sector [103,122]. About 3 million people are exposed to OPPs yearly, with the death rate reported to be 300,000, a very alarming figure [123].  (Organophosphate pesticide residues in environmental and biological matrices: Occurrence, distribution and potential remedial approaches)  Although they are very potent, they degrade relatively quickly in the environment compared with other classes of pesticides.  

The fastest route of absorption of OPPs is inhalation.  They can also be absorbed through the skin (transdermally).  The chronic effects of exposure to organophosphates include polyneuropathy, malignant diseases, neuropsychiatric diseases, and teratogenic effects (causing birth defects when exposed to a developing fetus).  They are also endocrine disruptors that can inhibit the development of sperm (Acute and Long-term Effects of Organophosphate Poisoning), which, of course, affects future generations.

Organochlorine pesticides (OCPs) are also very effective at killing insects by disrupting neural function.  There are many formulations, some of which are used on food crops like cashews and corn, some on “vector control” (insects or animals that carry disease-causing pathogens), and some against structurally damaging insects like termites.   OCPs are very persistent in the environment; persistence is defined as half-life greater than two months in water or six months in soil sediment. The persistence of OCPs varies from moderate persistence with half-life of approximately 60 days to high persistence with half-life up to 10–15 years.  The most infamous OCP is DDT, which is still used in some countries for mosquito/malaria control.  It is high persistence and a half-life of 2–15 years.  OCP toxicity is mainly due to stimulation of the central nervous system.  They also act as endocrine disrupting chemicals (EDCs) by interfering with molecular circuitry and function of the endocrine system.  Exposure can also lead to neuromuscular disorders and stimulation of drug and steroid metabolism. (Organochlorine pesticides, their toxic effects on living organisms and their fate in the environment)  OCPs are lipophilic, meaning that they end up accumulating in the fatty tissue of living organisms. 

People can be exposed to OCPs via inhalation if the chemical drifts from its application site, or the chemical can be absorbed through the skin, but the most common exposure route is ingestion because they are used on food crops, and children spending time on the floor can consume it in dust on the floor or on their toys. 

Older generations may say that they nor their parents were ever concerned about these exposures.  However, even low doses of these types of pesticides can affect many systems of the body and in the case of OCPs, remain in fatty tissue for years, even decades.  Any chemical that disrupts or alters thyroid function can cause diabetes, obesity and cardiovascular problems, which are endemic within older populations, therefore they may have the effects of pesticide exposure without knowing it!  So, what are the ways to avoid exposure to them?

Pesticides can be carried long distances in the air, so if you live in a rural area or one that is downwind of agricultural operations, parks, golf courses, etc., it’s possible that you could be exposed to them.  Activated carbon can remove many contaminants from the air, but some widely-used pesticides such as Chlordane, DDT/DDE/DDD cannot be removed by activated carbon alone (as well as the herbicide Glyphosate).  These require a specially enhanced adsorbent, which is included in certain air purifiers (see full list of pesticides that require this adsorbent here).  If you believe that air currents are carrying pesticides into the area of your home, try to stay inside, close any fresh air intakes for the peak exposure times, and use an appropriate mask outside.  According to this article, the black/pink cartridge (3M 60926) will filter out the organic vapors, dust, and mists typical of most pesticides. “Nuisance dust masks” like surgeon’s masks and cloth masks are NOT able to filter out pesticides adequately.  Teach children about the importance of not breathing in pesticides; although “running after the mosquito truck” was done in ignorance in the past, it’s really not excusable in this information age!   For example, a common insecticide is the organophosphate Malathion.  Malathion is of low toxicity to humans, but absorption or ingestion into the human body metabolizes malathion into malaoxon, which is substantially more dangerous. Symptoms of malaoxon toxicity can onset within minutes to hours after exposure, and can result in minor concerns such as allergic reactions or skin rashes to nervous system impacts, seizures, loss of consciousness, and even death.  Even low levels of exposure can lead to these effects. (Why One Group is Suing the Government Over Malathion, a Dangerous Pesticide)  Malathion is restricted to use in greenhouses only in Europe. (Banned and Hazardous Pesticides in European Food)  It’s easy to see why when you read some of the Malathion incident reports filed at poison centers. 

Here are some ways we suggest to avoid exposure to pesticides:

• Try to avoid being outside during pesticide spraying operations, and if you are very sensitive to pesticides, check out this article for specific air purifiers that can remove them from the air.

• Clean and dust regularly (especially if you have children who play on the floor) to remove pesticide residues that can settle in dust or be tracked in from the outside (removing your shoes and outer jackets at the door always helps too).

• Check out the Environmental Working Group’s annual list of “Dirty Dozen” and “Sweet 15” produce items to avoid vegetables with the most pesticides. 

• Soaking produce in water with baking soda removes some types of pesticides, better than a vinegar-water solution.

• This study showed that simply running leafy vegetables like spinach under water (for 5 minutes) provided the greatest reduction in most pesticides. (On average, removal using running water (77.0 ± 18.0%) and boiling (59.5 ± 31.2%) led to the highest reduction, whereas using detergent (43.7 ± 14.5%) led to the lowest reduction.)

• Peel vegetables if you can (like apples and potatoes).  A new method of visualizing pesticides on fruits like apples has shown that some pesticides penetrate the peel, even up to 30 nm into the pulp. 

• Buy organic to avoid many pesticides; however, organic does not guarantee there will be no pesticides. 

• Individuals with impaired activity of metabolizing enzymes may have an altered ability to metabolize pesticides.  If you opt for genetic testing, check whether you have the PON1 Q192R and GSTM1 null deletion, which are considered risk factors for pesticide intoxication and cardiovascular disease.  (Association of Paraoxonase-1 Q192R (rs662) Single Nucleotide Variation with Cardiovascular Risk in Coffee Harvesters of Central Colombia)  If so, you may be interested to know that in a 2017 study of 20 individuals consuming 25ml (<1 oz) of Extra Virgin Olive Oil (EVOO) per day, the EVOO consumption resulted in a significant decrease in oxidative damage to the lipid and protein fractions of the elderly people in the study, also increasing the anti-inflammatory activity of PON1 in these people.  EVOO is rich in oleic acid, a monounsaturated fatty acid, and also contains polyphenols like hydroxytyrosol and oleuropein, which are antioxidants.  Therefore, drinking a small amount of EVOO can actually help your body to combat accidental pesticide exposures.

Photo by Eric Brehm on Unsplash