The New Straits Times, April 24,1995
This week, the column that aims to educate and increase public awareness about what a poison is an how it affects us deals with arsenic, the kecubong plant, and glyphostate.
Question: Arsenic has been used in some herbicides, insecticides and rodenticides. It is also used in the treatment of timber. Given its wide usage, how can this poisonous element affect human beings?
Answer: Arsenic is a very common element in our environment. It is widely distributed in nature and mainly transported in the environment by water. Arsenic compounds are available in many forms and they differ substantially in their toxicity to mammals. The most to toxic arsenic compound is arsine gas. The solid form of arsenic salts have varying degrees of toxicity. If ingested, these salts can be rapidly excreted by the kidneys. Some arsenic compounds are apparently not toxic.
However, long-term exposure can lead to chronic poisoning with the following characteristic features:
joint pains (polyneuropathy), typically of the soles of the feet:
general complaints of fatigue, colic, and anorexia;
varying degrees of mental disturbances (encephalopathy);
skin problems including redness of the skin (erythema), hyperpigmentation, brittle nails, hyperkeratosis and baldness (alopecia);
decrease in the number of red and white blood cells; and
inflammation of the liver (hepatitis) and occasionally liver tissue death (cirrhosis)
In low concentrations of exposure, no significant symptoms are observed since human beings generally can cope with it.
In acute poisoning, the signs and symptoms may vary greatly, depending on the type of arsenic compound, dose, rate of ingestion and patient characteristics. Victims may experience metallic taste, burning and dryness of the oral and oesophagel mucosa. Subsequently, abdominal distress, headache, nausea, vomiting and diarrhoea may develop. The victim may have a garlic odour on their breath. With ingestion compounds, dilation of the blood vessels, a drop in blood pressure, mental disturbances and renal damage may occur. Hepatitis is also a frequent consequence of acute arsenic poisoning but this can usually be resolved in a matter of weeks.
Q: Why should the kecubong plant be planted away from the house?
A: The kecubong plant, also known as terung pungak, Datura starmonium or thorn apple has been known through the ages. It grows about 60 cm to 150cm tall with large leaves and funnel-shaped flowers. It is found everywhere, and has been quite commonly associated with plant poisoning. The entire plant, including the nectar (honey) it toxic. It contains alkaloids (hyoscyamine, atropine and scopolamine) which have a toxic effect when chewed or brewed.
The symptoms of intoxication include warm, dry, red skin; blurring vision; dry mouth; tachycardia; hallucinations; hypotension or hypertension; urinary retention; delirium, convulsions, coma; and death. Rising body temperature can occur in children. A couple of grammes of plant material can be lethal to a child.
Q: I have been using a weed-killer containing glyphosate. How safe is it?
A: Glyphosate is one of the many ingredients used in agriculture as a herbicide to inhibit the growth of unwanted weeds. Currently, there are about 75 registered herbicide products in Malaysia that contain glyphosate as the main constituent.
A number of research reports indicate that glyphosate exhibits its action selectively in plants and is relatively less harmful to animals and humans. Despite this, deaths have been reported from ingestion of a considerable amount of glyphosate products. Animal studies show that the toxicity of such products is attributable to an additive which acts as a surface-active agent or surfactant, normally used in conjunction with glyphosate.
The function of the agent is to increase the contact of water to glyphosate and hence increase the toxicity of the chemical. In case of glyphosate poisoning, there is no specific antidote and treatment is entirely supportive in nature. The signs and symptoms arising from such poisoning include sore throat, abdominal pain, vomiting with the presence of blood in the vomitus, difficulty in breathing, renal failure, cardiac failure and seizures. Thus, extra care should taken in storing and using these products.
