Tag: Health

Monocrotophos (The killer insecticide)

Monocrotophos is an organophospate insecticide mainly used on on citrus, olives, rice, maize, sorghum, sugar cane, sugar beet, peanuts, potatoes, soya beans, vegetables, ornamentals and tobacco and cotton. This highly toxic insecticide is prohibited in many countries.

English: A sign warning about pesticide exposure.
English: A sign warning about pesticide exposure. (Photo credit: Wikipedia)

Monocrotophos has oral, dermal and inhalation toxicity. This has resulted in death due to accidental exposure and suicides. Symptoms after oral exposure includes but not limited to excessive sweating, headache, weakness, giddiness, nausea, vomiting, hypersalivation, abdominal cramps, diarrhea, blurred vision and slurred speech. Inhalation and dermal routes may not show initial symptoms.

Severe poisoning will affect the central nervous system, producing inco-ordination, slurred speech, loss of reflexes, weakness, fatigue, involuntary muscle contractions, twitching, tremors of the tongue or eyelids and eventually paralysis of the body extremities and the respiratory muscles. In severe cases there may also be involuntary defecation or urination, psychosis, irregular heart beat, unconsciousness, convulsions and coma. Ingestion of 120 mg monocrotophos can be fatal.

Many incidents in developing countries have been linked to monocrotophos.  Monocrotophos has been pointed to as a cause, in the following:

Brazil, Parana State Monocrotophos caused 107 of 412 reported incidents analysed in 1990, and the toxicology centre and health clinics also noted 1,650 incidents involving monocrotophos between 1982 and 1991.

Paraguay In a region where monocrotophos is one of the most commonly used active ingredients there have been numerous cases of pesticide poisoning; monocrotophos was identified as the cause of paralysis in children in cotton-growing areas by the Ministry of Public Health and Welfare which found that 2–3 weeks of frequent exposure caused paralysis in children and acute poisoning in adults.

Egypt In a cotton growing region of Egypt the health of 14 farmers who spray was compared with a control group from the same region. Monocrotophos is widely used and 61% of those surveyed showed symptoms of chronic pesticide poisoning.

Philippines, Cordillera region Monocrotophos was one of the pesticides widely used by farmers in a survey that found all farmers suffered some adverse health effects.

Indonesia In observations of 906 spray operations of 214 farmers commonly using monocrotophos and other OPs, over a three-month period, researcher found a significant increase-from two to fiftyfold-in the symptoms of pesticide toxicity during the spraying period. Of these spray operations, 21% brought on three or more neurobehavioural and intestinal signs of poisoning.

India The 2013 incident where 23 schoolchildren in north-eastern India died from eating a contaminated school lunch is believed to have been caused by cooking oil stored in a container formerly used to store monocrotophos.

(Above quoted from Wikipedia)

English: Monsanto pesticide to be sprayed on f...
English: Monsanto pesticide to be sprayed on food crops. Français : Remplissage d’un épandeur (Photo credit: Wikipedia)

Transport regulation classifies Monocrotophos pesticides under class 6.1, toxic substances, packing group II or III depending on the products’ toxicity level.

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Toxicity – Transport Classification

Paracelsus, knows as father of toxicology wrote, “All things are poison, and nothing is without poison; only the dose permits something not to be poisonous.”

Paracelsus (born Philippus Aureolus Theophrastus Bombastus von Hohenheim, 11 November or 17 December 1493 – 24 September 1541)
Paracelsus (born Philippus Aureolus Theophrastus Bombastus von Hohenheim, 11 November or 17 December 1493 – 24 September 1541)

Poisoning can be caused by Chemical toxicants, Biological toxicants and Physical toxicants. Poisoning can effect the entire organism, specific organs or cells. The routes through which poison enter the body are oral, dermal or by inhalation.

As said by Paracelsus a specific dosage or above is required to cause poisoning. This dosage is measured in LD50   value for dermal and oral toxicity and LC50 value for inhalation toxicity.

Active/Lethal Dose Ratio and Dependence Potent...
Active/Lethal Dose Ratio and Dependence Potential of Psychoactive Drugs. Data source is Gable, R. S. (2006). Acute toxicity of drugs versus regulatory status. In J. M. Fish (Ed.),Drugs and Society: U.S. Public Policy, pp.149-162, Lanham, MD: Rowman & Littlefield Publishers. This is simply a rescaled version of the file listed in "other versions". (Photo credit: Wikipedia)

Let’s understand the basic concepts of LD50 and LC50 values.

LD50 = Lethal Dosage. Dosage required to kill 50 percent of the test animals, dosage, measured in mg/kg body weight.

LC50 = Lethal concentration. Dosage required to kill 50 percent of test animals, dosage measured in mg/per liter of volume of air.

Some examples

Placard for Toxic Substances
Placard for Toxic Substances (Photo credit: Wikipedia)
The hazard symbol for highly toxic substances ...
The hazard symbol for highly toxic substances according to directive 67/548/EWG by the European Chemicals Bureau. (Photo credit: Wikipedia)

IMDG Code

The word “toxic” has the same meaning as “poisonous” in IMDG Code. Toxic substances, liquids and solids, are classified under Class 6.1 and toxic gases under Class 2.3.

Definitions and properties according to IMDG Code

LD50 (median lethal dose) for acute oral toxicity is the statistically derived single dose of a substance that can be expected to cause death within 14 days in 50 per cent of young adult albino rats when administered by the oral route. The LD50 value is expressed in terms of mass of test substance per mass of test animal (mg/kg).

LD50 for acute dermal toxicity is that dose of the substance which, administered by continuous contact for 24 hours with the bare skin of the albino rabbit, is most likely to cause death within 14 days in one half of the animals tested. The number of animals tested shall be sufficient to give a statistically significant result and be in conformity with good pharmacological practices. The result is expressed in milligrams per kilogram body mass.

LC50 for acute toxicity on inhalation is that concentration of vapour, mist or dust which, administered by continuous inhalation to both male and female young adult albino rats for one hour, is most likely to cause death within 14 days in one half of the animals tested. A solid substance shall be tested if at least 10% (by mass) of its total mass is likely to be dust in the respirable range, such as the aerodynamic diameter of that particle fraction is 10 microns or less. A liquid substance shall be tested if a mist is likely to be generated in a leakage of the transport  containment. For both solid and liquid substances, more than 90% (by mass) of a specimen prepared for inhalation toxicity testing shall be in the respirable range as defined above. The result is expressed in milligrams per litre of air for dusts and mists or in millilitres per cubic metre of air (parts per million) for vapours.

Class 6.1, Toxic substances for packing purposes been assigned with packing groups according to the degree of their toxic hazards in transport.

Packing group I:   substances and preparations presenting a high toxicity risk;

Packing group II:  substances and preparations presenting a medium toxicity risk;

Packing group III: substances and preparations presenting a low toxicity risk.

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what is LD50?

In many Material Safety Data Sheets we see LD50 , What is LD50 ?

Definition of LD50 given in IMDG Code is “LD50 (median lethal dose) for acute oral toxicity is the statistically derived single dose of a substance that can be expected to cause death within 14 days in 50 per cent of young adult albino rats when administered by the oral route. The LD50 value is expressed in terms of mass of test substance per mass of test animal (mg/kg).”

The hazard symbol for toxic/highly toxic subst...
The hazard symbol for toxic/highly toxic substances according to directive 67/548/EWG by the European Chemicals Bureau. (Photo credit: Wikipedia)

Which means the amount of a substance required to kill at least 50% test animal when administered orally (in above case) with respect to their body weight.

LD50 is issued for toxicity in oral and dermal route and LC50 is used for toxicity in inhalation route.

Let us see some examples of LD50 which can kill 50% of adult albino rats compared to humans

LD50 for paracetamol is 1.944g , over dosage may cause death due to liver failure.

However this is not an absolute figure some may be killed with much less dosage than LD50 and some may survive much higher dosage.  These LD50 figures assist the experts in predicting toxicity giving a safe margin in practical applications.

LC50 – Lethal Concentration is also measured in same way for inhalation toxicity.

Skull and crossbones
Skull and crossbones (Photo credit: Wikipedia)

Dermal

LD50 for acute dermal toxicity is that dose of the substance which, administered by continuous contact for 24 hours with the bare skin of the albino rabbit, is most likely to cause death within 14 days in one half of the animals tested. The number of animals tested shall be sufficient to give a statistically significant result and be in conformity with good pharmacological practices. The result is expressed in milligrams per kilogram body mass.

Inhalation

LC50 for acute toxicity on inhalation is that concentration of vapour, mist or dust which, administered by continuous inhalation to both male and female young adult albino rats for one hour, is most likely to cause death within 14 days in one half of the animals tested. A solid substance shall be tested if at least 10% (by mass) of its total mass is likely to be dust in the respirable range, such as the aerodynamic diameter of that particle fraction is 10 microns or less. A liquid substance shall be tested if a mist is likely to be generated in a leakage of the transport containment. For both solid and liquid substances, more than 90% (by mass) of a specimen prepared for inhalation toxicity testing shall be in the respirable range as defined above. The result is expressed in milligrams per litre of air for dusts and mists or in millilitres per cubic metre of air (parts per million) for vapours.

Toxicity Classification for Sea Transport

Refer IMDG Code chapter 2.6 for classification criteria of toxic substances for sea transport.

ASTHMA INHALERS

Aerosol inhaler for asthma is a pressurized aerosol which when used will eject the medicine as aerosol into the lungs.

The content inside asthma aerosol inhalers is propellant and the medicine. Typically the propellant is almost 99% of the content.

CFC propellants are replaced by HFA (hydrofluoroalkane) propellants as CFC is an ozone depleting substance.  More information about HFA propellant inhalers can be found here.

Some of the asthma inhalers use 1,1,1,2-TETRAFLUOROETHANE as the propellant.

Cipla CFC-free inhaler (Generic Ventolin)
Cipla CFC-free inhaler (Generic Ventolin) (Photo credit: Wikipedia)

Since these inhalers are pressurized devices they will come under classification criteria of transport regulations. Aerosols are classified under UN 1950 in UN Model regulations.

Class 2.1 for flammables aerosols and class 2.2 for non-flammable aerosols.

However special provision 190 of model regulations states “Aerosols with a capacity not exceeding 50 ml containing only non-toxic constituents are not subject to the provisions of this Code.”

Inhaler capacity greater than 50 ML        = UN 1950 2.2

Inhaler capacity not more than 50 ml      = not hazardous for transport

Salbutamal metered dose inhaler.

IODINE

Iodine is an essential element for life. Deficiency of Iodine leads to hypothyroidism, goitre, mental slowing, depression, weight gain etc. Iodine is mainly used for nutrition and also for production of Acetic Acid.

Hypothroydism in Indonesia

Even though every essential for life, large quantity of Iodine is poisonous and this substance is also corrosive to most metals.

Based on human experience without using classification criteria of UN Model Regulations Iodine is listed under Class 8 ( Corrosive substances) with subsidiary risk 6.1 ( Toxic Substances ) UN 3495 and assigned to packing group III.

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