Organophosphate Pesticides

Organophosphate Pesticides: Toxic Effects On Our Environment and Us.
Laura DeMerchant, Victoria Dennis, Sam Demone, Bryden Tate, Dominic Talbot, Hayley Cable
Group #11
Earth Science 274
March 14th, 2014
Organophosphate Pesticides
In this rapidly developing world, people are continually exposed to numerous environmental pollutants such as industrial waste, polluted air and pesticides. The majority of pollutants are potentially toxic for organisms, some being connected to disease development. Pesticides are a very important group of environmental pollutants used in intensive agriculture for protection against diseases and pests. While their use improves the quantity of agricultural products it potentially affects their quality, as pesticides may enter human diet, this is a major current concern.
Organophosphate (abbreviated OP) is the general name for esters of phosphoric acid. Most OP pesticides are insecticides, although there are also a number of related herbicide and fungicide compounds. They form a large group of chemicals used over the past 60 years for protecting crops, livestock, and human health and as warfare agents. OPs are nerve poisons, which kill the target pest (usually insects). Their insecticidal qualities were first observed during the 1940’s, in Germany at the time of World War II, when the study of the extremely toxic OP nerve gases were present. Initially, the discovery was made in search of substitutes for nicotine, which was heavily used as an insecticide but in short supply in Germany.
OP’s are some of the most common, and most toxic insecticides used today. They are also an important defense against agricultural pests. All organophosphates are derived from one of the phosphorus acids, and as a class are generally the most toxic of all pesticides to vertebrates. Their acute toxicity causes a hazard both to professional and amateur users. The adverse short-term effects of exposure to these chemicals have been studied mostly in the nervous system, which is their primary target, even at low levels of exposer. Needles to say, organophosphate is very harmful to our species along with many more.
Pesticides and the Environment
The term pesticides is a large category of many smaller categories including insecticides, used for killing insects, fungicides, used for killing fungi, herbicides, used for killing weeds, along with others. Pesticides are toxic chemicals put into the environment to kill off pests in gardens, lawns, and homes. The problem with pesticides is that over 90% of the pesticides used today are killing things that they are not originally intended for. People have been overusing pesticides over the last number of years and the effects have been detrimental. Run off from the overuse is flowing into water streams which become the drinking water of animals and humans. The chemicals are poisoning wild animals that drink the water and causing them to die, or when a predator kills this animal, the poison will be consumed by the predator and will cause it to die, which is messing up their ecosystems. Another issue being caused by the over use of these chemicals is that they are killing household pets as well. When using the pesticides, if a household animal gets into it, whether it be your pet or a neighbours pet, it can get poisoned and die. The chemicals also have major effects on the plants in the environment. When people are over using these chemicals they are not only killing unwanted weeds or pests but could also be burning the plants in our ecosystem that helps many organisms survive. The chemicals from pesticides are also a cause of air pollution. While it may seem like a great idea to be spraying aerosols into the air to kill off mosquitoes and other pests, it will have negative effects on the air quality. Some side effects of this air pollution can range from headaches and nausea all the way to cancer and reproductive harm.
Due to the major overuse of these chemicals governments across North America have began to ban these from personal use. The ban for Nova Scotia was formed in April of 2011, and requires a special permit for use. The permit is only sold for business use and not personal use. Homeowners now need to contact an exterminator to rid their houses of any pests. While the ban exists on the more harmful pesticides, companies are now creating less harmful chemicals that are still permitted be used by everyone. While there are less toxic chemicals being manufactured for pest control, the safest way to protect ourselves and our environment around us is to use no toxins at all. Some ways of avoiding toxins would be to grow only organic foods, catch rodents with traps rather than poisons, let weeds grow or pick them by hand, and catch flies on tape traps, rather than using aerosols. Obviously this would cause more work for humans, but the safety of the environment over the long term would make it worth it.
Neuropsychiatric Evaluation in Subjects Chronically Exposed to OP Pesticides
This study performed clinical, neuropsychiatric, and laboratory evaluations on 37 workers involved in family agriculture and tobacco from southern Brazil who had been exposed to OP for 3 months. The results of the study found that the most common symptoms in the clinical examination and interview were fatigue, headache, hypertension, and dermatitis. Fifty two percent of participants had a lifetime history of at least mild cholinergic syndrome, with diarrhea, abdominal pain, and sialorrhea. Plasma acetylcholinesterase activity levels of all subjects were within the normal range. Twelve subjects showed clinically significant extrapyramidal symptoms. In conclusion this study reinforces the need for parameters other than acetyl cholinesterase activity to monitor for chronic consequences of chronic low-dose OP exposure and it suggests that subjects have not only transient motor and psychiatric consequences with exposure but also develop enduring extrapyramidal symptoms
Human Exposure to Pesticides
Humans, specifically labour workers such as farmers are at extreme risk of being exposed to pesticides such as OP. There are three primary types of ways that we can become exposed to pesticides, and they will be discussed in detail. The first is dermal and/or ocular exposure, which is exposure through the skin or eyes. The second type of exposure is oral, which entails the pesticide being directly through the mouth. Lastly there is respiratory exposure, which is exposure through the lungs. The first type of exposure and most common cause of pesticides entering the body is dermal or ocular exposure. Over 90% of human pesticide exposure is dermal. This consists of the process of the skin coming in direct contract with the pesticide, and the skin then absorbing the pesticide. Dermal exposure commonly occurs through a splash or spill of the pesticide, as well as residue coming into contact with the body when loading or applying the pesticide. Labour workers suffer from an increased threat to dermal exposure, as they often mixing pesticides that contain high percentages of active ingredients. The skin can act as a barrier to block the pesticides from absorbing it in our skin; however there are certain areas of the body that are at higher risks of absorption than others. For example the genitals and eyes are the most easily and rapidly absorbed part of the body, because they allow direct access to the inside of the body. Furthermore parts of the skin that are exposed through a cut or damaged are increasingly hazardous for this same reason. The second type of human exposure to pesticides is oral, which occurs when the pesticides are directly entered through the mouth. Oral exposure is the most severe type of pesticide poisoning as once it enters the body it can be absorbed in any part of the gastrointestinal tract, most commonly the pesticide is absorbed into the small intestine. Oral pesticide exposure can occur either by accident, carelessly, or intentionally. Most commonly oral exposure is the result of improper sanitization practices, such as not washing your hands prior to engaging in activities such as eating, drinking or smoking. Many foods, specifically fruits and vegetables are contaminated with pesticides, and thus the hazard of not washing them runs the risk of pesticide poising. Oral exposure also commonly happens through improper labeling. Humans, especially children are often poisoned when drinking out bottles that have been mistakenly labeled and contain pesticides, or from drinking out of bottles that have been previously contaminated. Labour workers such as farmers, generally consume high levels of pesticides as they are constantly handling high amounts of pesticides daily and do not take the proper precautions before eating and drinking. Furthermore most farmers use pesticides in their own backyard to protect their plants from insects. These pesticides commonly pass through the soil when left untouched by the plants, and seep into the groundwater. Therefore pesticides have the ability to travel into homes and be consumed through tap water. The last type of human exposure to pesticides that commonly occurs is respiratory exposure. Respiratory exposure occurs when pesticides are being inhaled, and can cause serious damage to the nose, throat, and lungs through absorption in the bloodstream. The lungs may be exposed to the pesticides through the inhalation of things such as powders, airborne droplets and vapours. Respiratory exposure is a great hazard because it often happens unintentionally. This is due to the fact that many vapours are odourless and extremely difficult to see, and hence we may be exposed without evening knowing.
Bodily Effects of Organophosphate Pesticides Organophosphate pesticides can enter and affect our bodies throughout four different passages (oral, inhalation, ocular and dermal). If these pesticides are ingested orally it may cause burning to your mouth, throat and stomach. In some cases the pesticide can also be carried throughout your blood stream causing physical harm in various ways. Inhalation alone can account for burning of your respiratory system making it more difficult to breathe and if such pesticide comes into contact with your skin or eyes it can cause severe irritation or itchiness. Organophosphate poisoning can also be classified in three separate ways, mild, moderate and severe. Some examples of mild cases include headache, mild muscle weakness and painful or blurred vision. Moderate cases show symptoms of fatigue, difficulty breathing, vomiting, marked muscle twitching or tremors and disorientation. Lastly the worst symptoms are the more severe, including convulsions, cardiac arrhythmias, coma and conceivably even death. Exposure to OP pesticides is known to induce three chemical syndromes and create biochemical alterations in human beings. Acute or chronic OP exposure can also induce delayed toxic and behavioural effects. These alterations and toxic effects are categorized under three more commonly known syndromes known as Acute Cholinergic Syndrome, Intermediate Syndrome and Organophosphate Induced Delayed Neuropathy. Acute Cholinergic Syndrome is the clinical syndrome that results in excessive stimulation of Acetylcholine receptors and occurs within minutes or hours following exposure. Related symptoms include muscle weakness and excessive secretory activity. Intermediate Syndrome occurs within twenty four to ninety six hours following the Acute Cholinergic Syndrome, characterized by respiratory paresis, weakness, depressed tendon reflexes and transient extrapyramidal symptoms. Organophosphate Delayed Neuropathy is a neuropathy caused by the killing of neurons in the central nervous system, occurs weeks following the acute exposure. Symptoms include sharp like cramping pains, resting tremor, rigidity face muscles and nonresponsiveness to levodopa treatment. If not treated the severity of this syndrome can result in paralysis of the legs and quadriplegia within the foot and wrist.
Psychiatric effects of Organophosphate Pesticides: There were many studies conducted which study the effects of organophosphate use and the psychiatric effects on children and adults. There are four studies that are going to be outlined and further discuss the diagnosis and management of COPIND – Chronic organophosphate- induced neuropsychiatric disorder. One study that was conducted at The University of California, Berkley Canter for Children’s Environmental Health Research is trying to foster relationships with the members of the community to reduce the effects of children becoming sick from Organophosphate uses. The center wants to build these relationships so that they are able to study the children. Another study conducted by the Center for the Health and Assessment of Mothers and Children if Salinas (CHAMACOS) is also trying to reduce children’s exposure to pesticides and other environmental agents, by doing this they are also trying to reduce the incidence of environmentally related diseases. Within this study there were four particular aims:
1. Explore Op exposure levels and pathways in pregnant women and their children
2. Identify predictors of Op levels in the body and the home
3. Observe exposure-prone behaviours in children at different developmental stages
4. The study continued until the child was 3 years old to determine whether exposure in utero and during postnatal period can be identified with disease, respiratory symptoms, slower or stunned growth, and poor neurological development. An interesting fact that was identified though research is that the suicide rate in Spain was high due to Organophosphate use, a link has also been made by the Royal Collage of Physicians & Royal Collage of Psychiatrists – show that is Organophosphate use or ingestion which is amounting to suicidal thoughts in individuals exposed to OP’s.
Many of the other long-term effects of exposure to Organophosphates also include anxiety problems, depression, confusion, personality change and loss of appetite.
One last study was conducted in Salinas Valley, California, which documented 526 mothers. The Results were taken when the children were 3.5 years and at 5 years. The results being mothers of 3.5 year olds reported clinical ranges for attention problems and the mothers of 5 year olds reported attention problems and ADHD symptoms, where both these results showed higher in boys than girls.
To diagnosis Chronic organophosphate- induced neuropsychiatric disorder COPIND it is mostly clinical and once a doctor has made the diagnosis of COPIND many patients will feel that all they need to do make changes in their lives to limit their exposure to Op’s. As stated above many patients just need to rearrange their lives to manage COPIND, however some patients need treatment in order for COPIND to be handled. It is important to also note that all these findings are only anecdotal evidence. There are three different ways explored to keep it under control and that is by antidepressants. SSRI’s (selective serotonin reuptake inhibitors) can help with suicidal thoughts and mood swings. There is also psychological treatment that a patient can undergo, which included counseling and support, rather than “formal psychotherapy” (Ahmed, Davies, Freer). One last way of manage COPIND is by general treatment which includes a prognosis of OP – induced diagnosis is uncertain, however there is no evidence of recovery. Op’s can lead to multi-system disorders such as peripheral and automatic neuropathy disorders, cardiorespiratory problems and possible premature osteoporosis.
Protecting Yourself from the Harmful Effects of Pesticides
Those in the greatest danger of pesticide illness are farmers and workers who mix and apply pesticides. Pesticide exposure causes farmworkers to suffer more chemical-related injuries and illnesses than any other workforce. People who reside near agricultural fields are more likely then urban residents to be exposed to farm chemicals. Chemicals affect everyone differently but children tend to be more sensitive to their effects. This is because they breathe in more air and eat more food relative to their body size, they also may not break down chemicals as effectively as adults do. One 2010 study found OP metabolites in 94 percent of children in the general population.
There are various ways to reduce your level of exposure to pesticides. You can buy organic and locally grown fruits and vegetables because non-organic fruits and vegetables are a major source of OP exposures among the general population. If you are on a limited budget, look for organic choices in the produce that you tend eat the most of if you can’t afford to go fully organic. National surveys have also shown that fruits and vegetables from farmers’ markets contain fewer pesticides even thought they may not organic.
Make sure to wash your fruits and vegetables before eating. You can even buy commercial vegetable and fruit washes that are available and formulated to remove chemical residue from produce. Know which vegetables have higher levels of pesticide residue. By knowing which fruits and vegetables pose the highest risks, you can take adequate precaution, such as washing those foods more carefully, peeling the skin on some fruit.
You can also protect yourself by drinking purified water because it is a well-established fact that we have pesticides in our tap water. Pesticide residues can get into our water supply from various sources such as farms, homes, or city parks. You should obtain Material Safety Data Sheets (MSDSs) for the pesticides you use. These sheets have details about precautions for use, safe handling and storage, manufacturer’s contact point, emergency procedures, health effects and first-aid.
Throughout this paper we have stressed the dangers and negative effects organophosphate pesticides have on the environment, and our bodies. Organophosphate chemicals are known for their effect on the human nervous system. It is important to take appropriate precautions noted in this paper to help reduce your exposure and protect your health.

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