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Organophosphate Pesticide Effects on Marginalized Communities

Pesticides are widely used the US agriculture economy. In 2007, organophosphates accounted for 35% of all pesticides used in the United States (US), and over 33 million pounds of it were sold in the US alone. Though there has been a significant reduction in usage and ubiquity since the 1990s, organophosphate pesticides are still used in conventional mass-production farming operations. Organophosphate pesticides are considered as a highly poisonous neurotoxin which targets central nervous system. The ubiquity of this pesticide, combined with the exposed population reveals a significant burden of risk for farmworkers, especially pregnant women and children.^[4][5] Although consumers are exposed to organophosphates as well, farmworkers are in contact with this pesticide in significantly higher quantities, and more frequently.^[6] Research shows that high-dose exposures can lead to measurable toxic effects in women (infertility) ^[7] and children (lower IQ),^[5] but the effects of long term, low-dose exposure are still debated.^[8]

Causal pathways and biology

Causal pathways

Organophosphates enter the human body via ingestion, dermal exposure, and inhalation.^[9] Although consumers can be exposed to organophosphates by eating crops treated with organophosphates, the primary concern with this chemical is with its ubiquity in farming operations across the world, and therefore, disproportionately affecting the farmworker population.^[6] Farmworkers are affected when they don't wear proper personal protective equipment ^[10]—in which case the chemical lands on skin, eyes, or other absorbent mucosal surfaces on the body— or, when they breathe in the chemical when it's sprayed in the field.^[11][10] Evidence suggests that dermal and inhalation exposure are the most toxic routes of expsure because substances do not have to pass through the liver for filtration as ingested substances do.^[9] Therefore, substances introduced to the body via breathing or skin contact are able to directly enter the blood stream, and to be distributed across the body more quickly and efficiently by bypassing the liver.^[9]

Biological systems affected

Nervous system

The primary symptoms of organophosphate poisoning are due to disrupted brain chemistry of the enzyme, acetylcholinesterase (AchE) and the neurotransmitter, acetylcholine (Ach).^[3] Ach is an essential neurotransmitter in the brain that controls several nervous systems and bodily functions. Normally in the brain, Ach is released by the presynaptic terminal and stimulates the postsynaptic terminal when it reaches the other side.^[12] However, Ach can only be broken down by its counter-enzyme, AchE. AchE plays a vital role in the neural synapse by regulating the levels of the neurotransmitter by breaking it down when appropriate.^[12] Too much or too little can cause overstimulation, or understimulation of neurons, which affects bodily function. In the case of organophosphate poisoning, the pesticide outcompetes Ach in the brain for the binding site of AchE, meaning the enzyme can't break down Ach, and causes enzyme inhibition.^[13] This leads to a build-up of Ach in the neural synaptic cleft, and results in overstimulation of the postsynaptic terminal.^[13] Organophosphate poisoning causes effects in the autonomic nervous system (parasympathetic and sympathetic), central nervous system, and the visceral motor system.^[13]

System Effects Autonomic Parasympathetic System Bronchospasm, Bronchorrhoea, Miosis, Lachrymation, Urination, Diarrhoea, Hypotension, Bradycardia, Vomiting, Salivation Autonomic Sympathetic System Tachycardia, Mydriasis, Hypertension, Sweating Central Nervous System Confusion, Agitation, Coma, Respiratory failure Visceral Motor System Muscle weakness, Paralysis, Fasciculations

Debated Carcinogenic Effects 

In a study conducted by the International Agency for Research on Cancer (IARC), an entity of the World Health Organization (WHO), organophosphates are were found to be attributed to a possibly increased cancer risk.^[14] However, different types of organophosphates have different carcinogenic risks— while tetrachlorvinphos and parathion were classified as "possibly carcinogenic", malathion, diazinon, and glyphosate have “limited evidence of carcinogenity”.^[14] The report acknowledges the limited information on the latter group of chemicals to determine causality, but the high correlation of cancer with malathion, diazinon, and glyphosate suggests this organophosphates are “probably carcinogenic” in humans.^[14] The report concluded that glyphosate has the potential to cause DNA or chromosomal damage, and may cause Non-Hodgkins’ lymphoma, or, cancer of lymph nodes.^[14]

The most commonly used organophosphate in this study group are glyphosates,^[14] the active ingredient^[15] in the common weed killer “Round-Up” produced by the Monsanto Corporation.^[15] Glyphosates are widely used on a global scale in crop agriculture as a weed killer.^[14] Round-up is also available for consumer purchase across home-improvement stores in the United States.^[14][15]

Due to the lack of scientific information and the significant financial implications for stakeholders around this product, there still lacks a consensus on the potential of glyphosate-caused cancers.^[16] In Mid-March 2017, a San Francisco judge ruled on some private emails between an EPA administrator and Monsanto that suggest the company had hired and paid scientists to ghostwrite industry led research.^[17] The resulting research report produced by Monsanto suggests that glyphosate does not have carcinogenic properties.^[17] However, there is also dispute within the US EPA, European Union, and other non-governmental organizations on the true carcinogenic properties of glyphosate, with parties on both sides of the argument.^[16][17] Further research is needed before a conclusive statement can be made.

Other effects

Reproductive system (luteal cells)

In an in-vitro study conducted in 2009,^[18] scientist found a strong correlation between organophosphate toxicity and the functionality of luteal cells. The luteal cells were exposed to cypermethrin, a pyrethroid at 90% concentration, and methamidophos, an organophosphate at 73% concentration.^[18] Though the study found more severe effects for the pyrethroid, the difference in effects were not statistically significant. This means that organophosphate exposure is highly correlated to decreased ability to produce progesterone in luteal cells, and also significantly increases the chance of luteal cell death.^[18]

Respiratory system

In a separate scientific article by scientists in 1991, a man in was accidentally exposed to organophosphates which led to the development of a rare respiratory disease, Adult Respiratory Distress Syndrome.[1]^[19] The patient also experienced extreme salivation and sweating, which are known parasympathetic effects of organophosphate poisoning.^[19]

Affected populations

According to the EPA, organophosphate use in 2004 accounts for 40% of all insecticide products used in the United States.^[20] Out of concerns for potential hazards of organophosphate exposure to child development, the EPA began phasing out forms of organophosphates used indoors in 2001.^[20] However, organophosphates are by far the most commonly used pesticide in the agricultural industry in the form of glyphosate, the primary ingredient of Roundup, totaling to about 185 million pounds per year, as compared to the second most commonly used pesticide, Atrazine, at 78 million pounds. While it is used in forestry, urban, and home applications as well, the general population has been observed to have low exposure.^[22] Thus, the primary affected population that faces exposure to organophosphates are farmworkers, especially those in countries that have fewer restrictions on its usage, such as India.^[23]

Contributing Factors to Farmworker Vulnerability in the United States

Race, Poverty, Documentation Status, and Linguistic Barriers

In the United States, migrant and seasonal farmworkers are the most susceptible to organophosphate exposure. Of the U.S. farmworker population, there are about 4.2 million seasonal or migrant men, women, and even children, 70% of which are born in Mexico and an overwhelming majority of 90% of all are Latino.^[24] This almost homogenous racial aspect of employment in farm work highly suggests social, economic, and political factors undercurrents that would explain their vulnerability in an increasingly anti-immigrant nation.^[25] Half of the farmworker population in the United States do not have legal documentation and two thirds live in poverty, making it difficult to fully understand and document the characteristics of this population with relative certainty.^[26] Furthermore, the group faces linguistic barriers, with about 70% of the migrant seasonal farmworker population reporting that they cannot speak English well.^[27]

In the United States, poverty and lack of documentation status puts migrant farmworkers in housing situations that make them far more likely to contract infectious or parasitic diseases and to suffer from chemical related ailments than the general U.S. population^[28]. Field workers who are exposed to pesticides continue to further expose their families in their residences, especially through contaminated clothing in which the residue settles as house dust. ^[27]

Economic, social, racial, and political barriers make passing policy and creating protective measures less likely to occur; in the context of their jobs, migrant seasonal farm workers are structurally vulnerable to exploitation and working conditions that are not up to health standards if they are unable to find the necessary physical and social resources to protect themselves.^[28]

Occupational Factors

The nature of their job demands constant exposure to toxins and pesticides and subjects them to increasingly extreme weather as climate change progresses. Thus, migrant farm work has been ranked conservatively as possibly the second most dangerous jobs in the country.^[29]

Developing World

Ethiopia

In Ethiopia, there are high rates of suicide associated with organophosphates. In a study conducted, the ratio of suicide of male:female is 1:1.5, where 45% of the cause is listed as due to "family disharmony" ^[41]. Though suicide is NOT a direct effect of organophosphate use, the ubiquity of this chemical in rural, poor, farming communities make it accessible as a means of suicide. ^[41]

Ghana

In Ghana, a study looked at the urinary concentrations of OPs in pregnant women. According to the study, third world populations are more susceptible to adverse health effects from chemicals due to 1) dumping 2) lack of regulations 3) ubiquitous use to control agricultural pests and vector diseases (malaria) ^[43]. In fact, the study found that there is more OP metabolites found in the women of the study, than compared to normal United States consumer exposures ^[43].

History of use

Organophosphates were first developed as a toxic nerve agent for biological warfare. In the 1930s,Gerhard Schrader, a German chemist, began work to develop organophosphate nerve gases under the Nazi government. Schrader and his team discovered the G-series which included tabun, sarin, and soman, all nerve agents. Though this chemical was not used in World War II, some of Schrader’s information was obtained by American companies and used to create pesticides after the war was over.^[32] This chemical was re-engineered to kill insects by targeting their neuralpathways, as opposed to that of humans. Many of the early pesticides were highly toxic but later corrected or toned down in toxicity. The use of pesticides in agriculture continues to cause adverse health effects for not only the farm workers, but many people who live in the surrounding area. Nerve agents were later put into use during the Iran-Iraq war from 1980-1988.^[33]

In the 1970s, organochlorine insecticides were banned, which paved the way for organophosphate insecticides.^[33] As a result, chemicals like DDT were banned in the United States but remnants remained in the water, air, and soil and can cause health issues. In fact, trace amounts are still found in chemical composition reports in people today. DDT's use in agriculture was banned in the United States but continued to be used in Mexico until 2000.^[34] It is reasons like this that contributed to its lingering effect on the environment.

Politics of Use

Trump Administration

President Donald Trump nominated Scott Pruitt, a republican politician from Oklahoma, to serve as the head of the Environmental Protection Agency (EPA) and assumed office February 17, 2017. Pruitt is an outspoken opponent of many of the EPA’s goals and programs, such as the degree of harm caused by Carbon Dioxide, the existence of climate change and the use of coal in modern industry. According to President Trump’s most recent budget proposal, the EPA’s annual budget will be cut by 33%. The EPA is already operating with a budget of $2 billion less that it had in 2010. In January of 2017, the EPA delayed the implementation of 30 different legislative regulations written by the Obama Administration. These actions dealt with the protection and limitations of environmental dangers including greenhouse gas emissions, renewable-fuel, and pollution limits. The blocking of these regulations is meant to either delay and revise or block entirely numerous crucial environmental policies.

Dow Chemical

Currently, a Dow Chemical, a large pesticide company, is pressuring President Trump to ignore studies on the damaging effects of pesticide use on crops and the effect on animals and people. Dow Chemical donated $1-million to the Trump inaugural festivities, as well as supporting the Trump campaign throughout the election. This pushback from Dow Chemical is seen in response to Pruitt’s recent announcement that he would be repealing the Obama Administration’s ban on the use of chlorpyrifos, a highly dangerous pesticide that has been linked to abnormal child brain development. Multiple studies, including over 10,000 pages of official research done by the Obama Administration, have all linked the use of organophosphates such as chlorpyifos and diazinon to birth defects, brain abnormalities and death, even when exposed at tiny amounts. Dow Chemical conducted its own study on the risks of organophosphates to counter the government’s and is using that study to attempt to ask the EPA to allow them. Chlorpyrifos is one of the most widely used pesticides in the United States. Given its frequent use on fruits and other crops, it often ends up in drinking water. A study conducted at UC Berkeley measured the levels of chlorpyrifos present in the umbilical cords of newly born babies and found that 87% of them tested positive for it.

While Trump and the associated members of the EPA are pushing for lighter regulations on pesticides, the congress is likely going to protect and uphold stronger laws about regulation. Congress is moving to reauthorize the Pesticide Registration Improvement Extension Act, which funds pesticide safety education and worker activities, funds reevaluation programs, information technology and labeling as well as stricter registration.