Pesticide poisoning
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A pesticide poisoning occurs when chemicals intended to control a pest affect non-target organisms such as humans, wildlife, or bees. Since label directions required by the FIFRA are specifically designed to protect applicators and other humans, wildlife, and other environmental resources, the majority of pesticide poisonings result from violations of the label directions.[citation needed]
A major exception to the above tendency, likely the worst single case of pesticide poisoning that has ever occurred, resulted from an industrial accident at a Union Carbide pesticide manufacturing plant in Bhopal, India. On the night of December 3, 1984, a leak erupted from one of the tanks of methyl isocyanate, a gas that is an intermediate step in the production of carbaryl and aldicarb. For two hours the gas poured out and into the surrounding community, killing at least 3,800 people, and permanently disabling 40 people. About 2,700 people were partly disabled and over 400,000 have lingering health effects. The worst damage was to the eyes and lungs of the victims, but there were many other physical and psychiatric symptoms as well. One reason the accident was so severe was that all safety and backup systems were either disabled or inadequate.
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[edit] Label
According to FIFRA, a pesticide is any substance or mixture of substances intended for preventing, destroying, repelling, or mitigating a living organism or any substance or mixture of substances intended for the use as a plant regulator, defoliant, or desiccant.
Pesticides are designed to kill organisms such as bacteria, bugs, fungi, or plants and can be toxic to other creatures as well, including: the applicator, workers (in fields or in professions that use disinfectants), birds, wild and domestic animals, and other beneficial organisms such as bees (our primary pollinators). The label for each chemical pesticide is designed after extensive company testing to maximize the effectiveness of the particular substance and to minimize risks. It often takes millions of dollars and several years to get a new substance labeled, i.e. approved for use, in the USA. Pesticide labels are also legal documents. Using the material contrary to the directions is a violation; deliberate use in violation of the label is a crime.
There are three important words used on pesticide labels have technical meaning:
- Caution: mildly toxic, more than an ounce would be a lethal dose for a human (less for children).
- Warning: more toxic, a teaspoon to a tablespoon is a lethal dose for an adult.
- Danger: (accompanied by the symbol of the skull and crossbones), highly toxic - a minute amount can kill an adult.
[edit] Acute poisoning of humans
It is critical, when pesticide poisoning is suspected, to get competent treatment as rapidly as possible. Since pesticides have different modes of action and different medical responses, it is also necessary to refer to the label. If you are using a pesticide, be sure a copy of the label is present and accessible before you begin use. If you are rendering first aid, if at all possible, obtain a copy of the pesticide label for yourself and for the medical personnel.
[edit] Anticholinesterase poisoning
| Pesticide poisoning | |
|---|---|
| Classification and external resources | |
| ICD-10 | T44.0 |
| ICD-9 | 971.0 |
If one is regularly using carbamate and organophosphate pesticides, it is important to obtain a baseline cholinesterase test. Cholinesterase is an important enzyme of the nervous system, and these chemical groups kill pests and potentially injure or kill humans by inhibiting cholinesterase. If one has had a baseline test and later suspects a poisoning, one can identify the extent of the problem by comparison of the current cholinesterase level with the baseline level.
Anticholinesterase poisoning may be treated with muscarinic antagonist, e.g. atropine.[1]
[edit] How poisonings occur
Pesticides can enter the body from inhalation, ingestion, or eye or skin contact. Many cases of poisoning occur to applicators who did not read the label and worked without proper protection. Another scenario is that pesticides are directly applied to farmworkers in the field, or that they re-enter a treated field before the toxicity levels drop to acceptable levels. Take-home exposure to children of workers has also been documented. Furthermore, self-poisoning with agricultural pesticides represents a major hidden public health problem. It is one of the most common forms of self-injury in the Global South. The World Health Organization estimates that 300,000 people die from self-harm each year in the Asia-Pacific region alone.[2] Contrary to the western stereotype of self-poisoning, most cases of intentional pesticide poisoning appear to be impulsive acts undertaken during stressful events, and the availability of pesticides strongly influences the incidence of self poisoning. NIOSH tracks occupational pesticide exposures in the United States, however it is thought that many—if not the majority—of exposures occur when unlicensed applicators apply over-the-counter pesticides.
[edit] Chronic poisoning, genetic damage, and birth defects in humans
Rachel Carson's Silent Spring brought about the first major wave of public concern over the chronic effects of pesticides. The organochlorine pesticides, like DDT, aldrin, and dieldrin are extremely persistent and accumulate in fatty tissue. Through the process of bioaccumulation (lower amounts in the environment get magnified sequentially up the food chain), large amounts of organochlorines can accumulate in top species like humans. There is substantial evidence to suggest that DDT, and its metabolite DDE, act as endocrine disruptors, interfering with hormonal function of estrogen, testosterone, and other steroid hormones.
There is speculation of a pesticide contribution to Parkinson's disease, see section on Toxins.
Certain organophosphates have long been known to cause a delayed-onset toxicity to nerve cells, which is often irreversible. Several studies have shown persistent deficits in cognitive function in workers chronically exposed to pesticides (Jamal et al. 2000). Newer evidence suggests that these pesticides may cause developmental neurotoxicity at much lower doses and without depression of plasma cholinesterase levels.
[edit] Statistics
Acute pesticide poisoning is a large-scale problem, especially in developing countries.
"Most estimates concerning the extent of acute pesticide poisoning have been based on data from hospital admissions which would include only the more serious cases. The latest estimate by a WHO task group indicates that there may be 1 million serious unintentional poisonings each year and in addition 2 million people hospitalized for suicide attempts with pesticides. This necessarily reflects only a fraction of the real problem. On the basis of a survey of self-reported minor poisoning carried out in the Asian region, it is estimated that there could be as many as 25 million agricultural workers in the developing world suffering an episode of poisoning each year." (Jeyaratnam J., 1990).
Estimating the numbers of chronic poisonings worldwide is even more difficult.
[edit] Poisoning of other non-target organisms (wildlife, bees)
An obvious side effect of using a chemical meant to kill is that one is likely to kill more than just the desired organism. Contact with a sprayed plant or "weed" can have an effect upon local wildlife, most notably insects.
[edit] References
- ^ Rang, H. P. (2003). Pharmacology. Edinburgh: Churchill Livingstone. ISBN 0-443-07145-4. Page 147
- ^ WHO. The impact of pesticides on health: preventing intentional and unintentional deaths from pesticide poisoning. 2004: http://www.who.int/mental_health/prevention/suicide/en/PesticidesHealth2.pdf
[edit] Notes
- Jamal GA, Hansen S, Julu PO. Low level exposures to organophosphorus esters may cause neurotoxicity. Toxicology. 2002 Dec 27;181-182:23-33. Review. PMID 12505280
- Jeyaratnam J. Acute pesticide poisoning: a major global health problem. World Health Statistics Quarterly. 1990;43(3):139-44.
[edit] Further reading
Pesticides, a toxic time bomb in our midst. Marvin J. Levine, Praeger Publishing 2007.
[edit] See also
[edit] External links
- National Pesticide Information Center (NPIC) - Objective, science-based information about pesticide-related topics
- Physician's Guide to Pesticide Poisoning
- Environmental Protection Agency - Recognition and Management of Pesticide Poisonings
- The Pollution in Newborns - From the Environmental Working Group
- Find Your Local Poison Control Center (Worldwide)
- WikiTox Information & Teaching material on human toxicology
- Texas Department of State Health Services Pesticide Exposure Surveillance in Texas program information and useful links
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