Malaria as One of the Leading Causes of High Mortality - Article Example

Malaria is one of the leading causes of high mortality rate especially to young children below the age of five years and pregnant women in Africa (ATSDR, 2002). High resistance to drugs and insecticides has made the control of malaria a challenging task globally. However, of all insecticides used to control malaria vectors, DDT has the highest proven efficacy. The use of DDT for internal residual spraying is one of the most effective methods of controlling the spread of malaria (WHO, 2007). DDT has high toxicity levels to human health and environment and these factors have lead to its restrictive use even in malaria endemic regions like Africa by environmental and health stakeholders. However, due to high prevalence and mortality rate associated with malaria, I suggest review of the policy governing the use of DDT and the insecticide be reintroduced to prevent high malaria outbreak in African continent. To make this decision, it is important to have toxicological data on the effects of the insecticide on human health and the environment. Concerns about toxicity of DDT on human health are based on the storage of the compound and its metabolites in the human body fat, the occurrence of DDT residues and its radicals in human milk, the potential of causing cancer in addition to fears of interfering with hormones in the body (WHO, 2007). From these concerns, it is important to have toxicological data regarding its effects on various physiological processes in the body. These include effects on respiratory, reproductive and circulatory systems among others. Currently, toxicological data on DDT indicates that exposure to high concentration of the insecticide within half an hour does not cause permanent health effects (CDC, 2010). In addition, the insecticide has low order of severe toxicity when inhaled (CDC, 2010). ATSDR (2002) lists the four phases of disposition of toxic compound in assessment of its toxicity. Absorption of a compound into the body is the first phase, followed by its distribution in the body in the second stage. The third phase entails metabolism or the breakdown of the compound in the body and finally secretion of the chemicals from the body is the fourth and final phase (ATSDR, 2002). DDT enters the body through contact of the chemical with skin and the mouth when swallowed. WHO (2007) notes that the insecticide has marginal severe toxicity on dermal contact but is extremely poisonous when taken orally. The first phase of absorption involves the movement of molecules across membranes. In this respect, the type of membrane that a toxic compound comes into contact with plays a great role in determining subsequent level of poisoning. DDT is soluble in lipids and as a result, it is absorbed into the body through passive diffusion. This process depends on the solubility of a particular compound in the lipid layer of the particular membrane. Therefore, the high solubility of DDT in lipid enhances its absorption into the body (ATSDR, 2002). The plasma normally undertakes the role of distributing DDT and other compounds in the body tissues, organs and cells. According to ATSDR (2002), the process of distribution is complicated but it mainly depends on the attraction of the particular substance to the various issues in the body. Most chemical compounds that attach to the plasma are bind to albumin, a very important protein in the plasma that plays a critical role in distribution of substances in the body. According to ATSDR (2002), toxic chemicals including DDT compete and eventually displace the endogenous compounds that bind naturally to proteins in the plasma. In addition, artificially introduced chemicals in the body including drugs and other environmental substances sometimes compete with each other for binding sites and dislodge one another from the active transport sites. DDT is distributed in similar mechanism in the body and it is eventually stored in various body tissues (ATSDR, 2002). DDT metabolism occurs through various processes including atmospheric photo oxidation, photolysis in water and soil in addition to slow biodegradation of the compound to form DDE and DDD metabolites. These substances could be decomposed further to form other metabolites. The longevity of DDT and its metabolites in addition to their high solubility in body lipids have enhanced their bioaccumulation and biomagnification in the body tissues and the environment (ATSDR, 2002). ATSDR (2002, p 85) defines bioaccumulation as “the increasing concentration of chemicals or compounds to a level that is higher than the environment in which the organism lives”. Biomagnification refers to “the proportionate increase of accumulated substance in the body of an organism in relation to the trophic level of the organism” (ATSDR, 2002). This implies that organisms higher in trophic levels have higher accumulation of DDT and other toxic chemicals than those in lower levels (ATSDR, 2002, p 126). The absorbed DDT and the subsequent metabolites are normally stored in the adipose tissue of organisms (WHO, 2007). The level of accumulation depends on the duration of exposure and the quantity of DDT absorbed into the body. DDT is excreted through various pathways including milk and urine because of its high solubility in lipids (ATSDR, 2002). Therefore consuming milk from an animal contaminated with DDT leads to the introduction the compound in the body. Infants can also ingest the compound by suckling milk from mothers exposed to the compound. Therefore, exposure to DDT in human beings arises from skin contact, swallowing the toxic compound or consuming organisms that have been previously exposed to the compound. Accumulation of the compound through the food chains in the most common pathway through which the chemical accumulates in the body (ATSDR, 2002). DDT causes various effects on the body. Some of the adverse effects include impairment of nerve impulse coordination. According to ATSDR (2002), nervous impairments have been observed in animals and human beings and they are often characterized with tremors and convulsions. However, human beings have higher tolerance to the chemical than other animals. Animals exposed to the compound normally die from respiratory arrest. Other concerns about exposure to DDT include interference with reproductive system and causing various types of cancers (WHO, 2007). It is apparent that DDT has serious health and environmental effects to human beings and animals in spite of its high effectiveness on malarial vectors. However, Malaria is one of the leading causes of high mortality rate in Africa in spite of implementation of various the vector control initiatives. Continuous use of DDT could help in eliminating the malaria vectors that have become increasingly resistant to pyrethroid-based insecticide. However, application of DDT should be done with extreme caution to minimize exposure of the chemical to animals and human beings. References ATSDR (Agency of Toxic Substances and Disease Registry).(2002). Toxicological profile for DDT, DDE and DDD. Washington DC: Public Health Service, Department of Health and Human Services. CDC (2010). Documentation for immediately dangerous to life or health concentrations: DDT. Retrieved on September, 2, 2011, from http://www.cdc.gov/niosh/idlh/50293.HTML WHO (World Health Organization). (2007). The use of DDT in malarial vector control: WHO position statement. Retrieved on September 1, 2011 from http://whqlibdoc.who.int/hq/2007/WHO_HTM_GMP_2007_eng.pdf Read More