Chemistry

A majority of substances used by humans in daily life such as air, water and food contain thousands of unknown substances. Other organisms also present in the environment such as insects, animals and microorganisms may be harmful to humans and can result in serious health effects on human beings. The following paper will examine health risks in relation to pesticides, chemical contaminants and natural toxins.

Their history, mode of manufacture, safety and toxicity, relevance and importance based on their current uses and their relation to laws and legislative issues will also be discussed. Finally, measures taken to prevent harm and poisoning due to these substances will be looked at and future needs and concerns analyzed

Introduction
Most harmful organisms are normally present in the form of pests and include house flies, mosquitoes, weevils, locusts and disease  pathogens such as bacteria, viruses and fungi .some of these transmit disease vectors directly to humans while others attack foodstuff like vegetables and fruits which if ingested lead to health problems. Some foods have natural toxins which enable them to resist these insects. They include potatoes which contain a toxic component known as solanine among other glycoalkaloids that usually occur at low level (NZFSA, 2010).

As a result, when these foods are wrongly handled they can in turn cause food poisoning. Pesticides, which are also developed to destroy certain harmful insects and prevent diseases, can be harmful to human beings when they are exposed to certain levels as they are mostly sprayed. On the other hand, chemical contaminants may be chemicals related to cooking and heating procedures and include acrylamide (Health Canada, 2010) .

Pesticides are designed in a toxic manner to certain forms of life and are widely used in the environment as a control against pests. However, huge public concern is developing in relation to their use as they can pose serious health problems. This is due to contamination of drinking water in both agricultural and urban regions. The residues are also found in almost all places including offices, homes, on food and in the air. This necessitates the continuous monitoring to protect human populations from this problem (Levine, 2007)
Among the various forms of pesticides are the chlorinated hydrocarbons (Levine, 2007). An example of these forms is dichlorodiphenyltrichloroethane or DDT. The IUPAC name for this chemical which has a molecular formula of C14H9Cl5 is 1,1,1-trichloro-2,2-di(4-chlorophenyl)ethane. The molecular structure of DDT is as shown in Figure 1.

Although it is not a very chemically reactive chemical, it is normally involved in one important dehydrochlorination chemical reaction to form 2,2-bis(p-chlorophenyl)-1,1-dichloroethene or p,p-DDE. This occurs in the presence of KOH, NAOH, and other strong alkalis.(National Research Council  US, 1952) as shown
(C6H4Cl)2 CHCCl3  OH-  (C6H4Cl)2CCCl2  Cl-  H2O.

The chlorine produced from this reaction is measurable, aqueous and depleted isotopically, and is therefore usefully used as a tracer of these reactions in environments with fresh water (National Research Council US, 1952).

On the other hand natural toxins occur naturally in food and in some plants which have the ability to produce toxic compounds if ingested by humans under certain conditions such as when raw or when improperly prepared or cooked (Health Canada, 2010). Some of the naturally occurring toxins include ipomeamarone, furocoumarins, lectins, oxalic acid, cucurbitacins,cyanogenic glycosides, and toxic honey (NZFSA, 2010) Some of these natural toxins can however at times be man made.

Another major health risk can be posed by food-borne chemical contaminants which can either be organic, inorganic or radioactive (Artiola, Pepper  Brusseau, 2004). These chemical contaminants become pollutants only when their levels accumulate sufficiently to cause negative environmental and health effects. They include Acrylamide, industrial chemicals such as dioxins, furan, radionuclides and melamine (FDA, 2009). Most sources of fish also contain these chemical contaminants like mercury posing serious effects if eaten.

Production and the Adverse Effects on Humans
Pesticides can get into ground water and hence contaminating drinking water in different sources. Their negative health effects are experienced by all people but are majorly found among children, pregnant women, farmers and farm workers, and the elderly (Levine, 2007 p.1). They include acute poisoning, cancer, damage to the neurological system, birth defects and harm associated to reproduction and development. In addition, the normal responsiveness of a persons immune system has been found to be suppressed resulting to vulnerability of the body to invading pathogens such as viruses, bacteria, parasites and tumors. Moreover, the exposure to pesticides has revealed a decrease in sperm counts (Levine, 2007).

Some of the foods that may contain natural toxins include fruit seeds and pits like apple and pears seeds and Kernel of apricots and peach contain naturally occurring substance called amygdalin which can turn into hydrogen cyanide in the stomach causing discomfort or sickness. Other examples include kumara, potatoes, kidney beans, zucchini, toxic honey and rhubarb (NZFSA, 2010).

Although the degree of reactions and symptoms experienced depend on an individuals sensitivity to a toxin and the amount of concentrations, natural toxins present general side effects. These include vomiting, stomach cramps, diarrhea, collapse, muscle twitching, cramps, decreased breathing and heart action, pain, headache, convulsions and coma and at times they cause a painful skin reaction when ultra-violet rays of the sun are combined in the contact with the parsnip plant. In worse situations they can even lead to death (NZFSA, 2010).

Before the advent of synthetic pesticides was introduced in the nineteenth century with the use of sulphur compounds as fungicides, naturally occurring substances such as pyrethrum were being used by farmers. Arsenic compounds were later developed to control insects which attacked fruits like apples and grapes and vegetables. For instance, DDT was first synthesized by Othmar Zeidler in 1874 (WHO, 1979). However, its properties were only discovered in 1948 by Paul Hermann Muller, a Swiss scientist who won a nobel price award for his efforts in physiology of medicine (Nobelprice.org, 2010).

As there was a short supply of pyrethrum at that time, DDT became widely used in Europe during the Second World War to control insect vectors that caused typhus and also as weapons of war. As a result, it almost wiped the disease out completely.  With additional impressive effects, it was also used in the South pacific for malaria control where it was aerially sprayed to kill the mosquitoes. The use of pesticides also ensured increased agricultural production because they decreased the number of insects which were a natural threat to crops (Levine, 2007).

Whereas natural toxins were discovered by Homo sapiens in ancient times and were used in hunting as arrow poison, they are still currently put to use in hunting and for ethnic wars in Asia, Africa and South America. They are also used as molecular markers in studies of designing functional membrane and structures of cells due to their high efficiency and selective effect they are used as molecular (Gelashvili, 2002).

The manufacturing process of pesticides involves the manufacture of major compounds such as carbamates and dithiocarbamates, chlorophenol compounds, organochlorines, and miscellenious compounds like biopesticides and pyrethroids. It goes through the main processes of preparing process intermediaries, functional groups introduction, coupling and esterification, processes that involve separation and final product purification. Emissions of substances in the air such as volatile organic compounds and particulate matter, liquid effluents that contain pesticide residues and toxic organics as a result of equipment cleaning after operations and solid wastes are generated from each of these steps (World Bank Group, 1998).

Natural toxins are therefore natural chemicals that occur in food which include carbohydrates, protein, sugar and vitamins essential for growth and health. However, when they are contained in some foods they become possibly harmful. At times, certain climatic conditions favor growth of toxic producing fungi on food crops. Furthermore there can also be bacterial toxins as well as those produced by algae and molds (Phelps  McKillip, 2002).

Chemical contaminants can be environment related where the chemicals manufactured for industrial use break down easily due to their stability hence can enter the food chain when released (Williams  Hammit, 2001). Others although they occur naturally, their mobility is increased by industrial activities making their entry levels in food chains higher than usual. Some contaminations are induced by food processing as a result of reactions between naturally occurring food components or the intentional use of food additives which react with another compound (Health Canada, 2010).

Current Uses
Besides the control of malaria among other diseases spread by insects, pesticides can also be used for agricultural activities (Levine, 2007). Currently, the types of pesticides in use are grouped into three. They include insecticides, which are meant to eliminate destructive insects. These can be sprayed directly or used to dose a particular area. There are also herbicides or weed- killers, which like insecticides, can be selective for particular kinds of unwanted plant. Fungicides on the other hand are used for moulds, rots and several plant diseases. They must be sprayed widely since they have to come to direct contact with the fungus.
On the contrary, is not yet clear why the natural toxins occur in some plants. The presence of natural toxins in some plants, however, act as natural pesticides to prevent the attack by insects, as a reaction when the plant has been stressed by micro-organisms, and damaged such as in bruising, and also as response to injury.

They are additionally available to prevent the plant from spoilage when damaged by weather. Toxins may also be produced to protect the plant from ultra-violet light, handling or microbes (NZFSA, 2010).
Additionally, agricultural chemicals are used for increase of crop yields, weeds and pest controls and prevention of crop and livestock diseases and can also be classified as chemical contaminants. These include pesticides, herbicides, regulators of plant growth, growth hormones and veterinary drugs or antibiotics (Dionex Corporation, 2010).

Legislative Issues for Prevention and Control against Harm by Toxic Substances
There is however some hope since there are ways to reduce pesticide use and exposure (Levine, 2007), because a lot of emphasis has currently been laid on microbial safety and food defense with regards to the food industry (DeVries, 2006). Various laws and regulations such as environmental law, water quality regulation, and pesticide regulation among others have been set up to provide guidance on how people should handle wastes, food and other substances with regards to safety (Levine, 2007) . Agencies such as the UK Food Standards Agency give recommendations on the specific amount of food substances to be included in a dietary intake for example not more than two apricot kernels daily (NZFSA, 2010). They also provide guidelines on how to prepare and cook various foods that contain toxic substances
In order to prevent such bodily harm to consumers, food producers should test plants and animals for chemical residues. The introduction or delivery of food into consumer markets and global trade in general is also regulated by bodies such as the Federal Food, Drug and Cosmetic Act (FFDCA). This ensures that those purchased and consumed do not contain any poisonous or dangerous substances like chemical contaminants which may be harmful to human health hence overseeing food safety. As a result natural toxins such as mycotoxins, pesticides, industrial chemical which include dioxins are assessed and potential exposure and risk eliminated (FDA, 2009).

Research is also conducted by health scientists to assess and understand effects of certain chemicals on the human body. As in the case of chemical contaminants, there are set regulations concerning the annual or lifetime rates of application for pollutants such as heavy metals which are sometimes used as plant or animal micronutrients. There are also restrictions as to the maximum amount of organic pollutants in biosolids such as pesticides allowed for use (Artiola, Pepper  Brusseau, 2004).

Efforts should also be made for replacement of highly toxic and persistent pesticides ingredients with those that are degradable and less toxic. To prevent pollution some of the recommendations are use of high pressure hoses to clean equipment and reduce waste water, the reuse of processes by products as raw materials or substitutes for raw materials in other processes and the appropriate use of nitrogen blanketing on pumps, storage tanks and other equipment to reduce the amount of toxic organics released (World Bank Group, 1998). Consequently, due to presence of food toxins, a number of products have been recalled, alerts provided on public health and trade issues have occurred (DeVries, 2006)

Conclusion
In general, due to the detrimental effects of toxins, strict measures should be taken to avoid diseases caused by such toxic materials. Food should be well prepared and properly cooked to prevent poisoning from natural toxins. Good manufacturing practices should also be implemented to destroy natural toxins. In addition, manufacturing companies that deal with the production of such material and pesticides should minimize the amount of toxic waste products released or treat them to remove toxicity. Agricultural chemicals and wastes from factories should be correctly handled to prevent them from getting into water sources or accumulate to dangerous levels in the soil.

More specific laws and regulations should be established and strictly adhered to so as to ensure the safety of consumables. In addition, before the toxicity of a new substance is established, it should be held back till the necessary research is completed and it is found to be harmless. If such steps are taken, it will help in elimination of risks associated with these and many more substances.