Toxicological Effect on Behaviour and Body Weight of Broiler Chicks Exposed to Carbaryl and Zinc

Table of contents

Summary

Chapter One
Introduction

Chapter Two
Toxicological profile of carbaryl
Toxicological profile of zinc

Chapter Three
Health effects of carbaryl
Health effects of zinc

Chapter Four
Methodology

Chapter Five
Results and Discussion
Effect of carbaryl on body weight
Behavioural effects of carbaryl
Effect of zinc on body weight
Behavioural effects of zinc

Bibliography

List of tables

Table No.1: Recommended Dietary Allowances (RDA) of Zinc by different age groups and Gender

Table No. 2: Values of Acute LD50 0f Carbaryl for various Birds species

Table No. 3: Different carbamate pesticides with their toxicity level

Table No. 4: Effect 0f Carbaryl for various Birds species

Table No. 5: Effect of Zinc on different body parts of Humans

Table No. 6: Sources and symptoms of zinc poisoning in birds

Table No. 7: Types of Pesticides and their health effects

Table No. 8: Carbamate Pesticides and Their Effects on Endocrine System

Table No. 9: Zinc content in different foods

Table No. 10: Body weight changes (Mean±S.E.) in broiler chicks exposed to different doses of carbaryl (n=5)

Table No. 11: Body weight changes (Mean±S.E.) in broiler chicks exposed to different doses of Zinc (n=5)

List of figures

Figure. 1: Chemical Structure of Carbaryl

Figure. 2: Mode of action of Carbamate Insecticide

Figure. 3: Effect of carbaryl administration on body weight in broiler chicks

Figure 4: Effect of Zinc administration on Body weight in broiler chicks

Summary

Pesticides and heavy metals are of great importance for pest control in agriculture, various diseases in poultry and for growth in poultry simultaneously. Carbaryl a carbamate insecticide is used in poultry industry for destroying and preventing the pest and vectors for various animal diseases. Carbaryl inhibit the acetylcholinesterase (AChE) activity in vertebrates, insects and human beings. While zinc is used in poultry industry for their growth and for normal functioning of different biochemical process in the body. If pesticide enter in the body in excess i.e., above the lethal dose than it can change the function of hormones, neurotransmitters, physiology, morphology and behaviour. This study was conducted to examine the effect of Carbaryl and Zinc on body weight and behaviour of broiler chicks.

Statistically insignificant (p>0.005) increase in the body weight were found in the experimental animals as compared to control was recorded with different doses of carbaryl. While in zinc treated chickens statistically insignificant p>0.005 increases in the body weight of the experimental animals were found as compared to control were recorded with different doses of zinc.

Behavioural impacts were examined by looking at changes in activity patterns. Leg weakness ,frequent defecation, less food consumption and dizziness in broiler chicks were found given high dose of carbaryl after one week but the birds fed zinc showed an increase in behavior with increasing concentration up to a certain point, nervousness, leg weakness, and fluffed feathers were found in intermediate and high dose groups. On the other hand, relaxed, happy broiler chicks will vocalize frequently, eat hungrily, preen normally in control group.

Chapter One

Introduction

Concern regarding the welfare of animals permeate are all levels of society. The increasing pollution, decreasing habitats and the destruction of feeding and breeding areas has pushed animals to the very extreme living conditions. Birds suffer most of all as they live near humans more than any other species. 87% of threatened bird species affected by agriculture(BLI, 2008).Various bird species are indicators of ecological integrity. If the number of bird species decline continuously it leads to collapsing ecosystem (US FWS, 2002) because birds have unique role in ecosystem functioning such as pollination and dispersal and also play important role in restoration of disturbed ecosystem (Sekercioglu et al., 2004). Pesticides are of great importance for pest control in agriculture, in homes and for controlling the pest and various diseases in poultry (Crespo-Corral et al., 2008).

Pesticide is a substance or mixture of substances which is intended for destroying, preventing and controlling the pest and vectors of human and animal diseases and harmful species of human and plants which causing harm during the production, storage, processing of food, agricultural commodities which may administered to animals for control of insect and other pests in their bodies (FAO, 1986a). Some of the pesticides are of biological origin such as Bacillus thuringiensis which is used in public health programmes to control mosquitos and malaria. Pesticides have become omnipresent contaminants of environment, found in water, air and soil. Exposure of humans and animals to pesticides causes severe abnormalities in both pesticides penetrate through skin and accumulate in the tissues of both humans and animals (Anwar, 1997).

Humans and animals are unintentionally exposed to lethal and sub-lethal doses of various pesticides. Both can be exposed to pesticides directly by ingestion and inhalation (Eddlestone, 2000; Martin et al., 2003). Some of the pesticides store in mammary glands because these pesticides are lipophilic and bioaccumulate in lipid stores. These lipophilic pesticides passed to the developing fetus during pregnancy and lactation along with lipid or via placental transfer(Sonawane, 1995; Khanna et al., 1991; Sitarska et al., 1995).Various human disease vectors are controlled by spraying or by treating surface water with insecticides and herbicides to control aquatic weeds. Water may be polluted when:

- Leakage and run- off of pesticide

- After spraying discharge of surplus pesticides
- Equipments which are used for spraying are washing or poured into the rivers, lakes and ponds
- When pesticides apply to the rivers and ponds to kill aquatic weeds
- Accidental spillage of Pesticides

The use of pesticides in agriculture has increased the productivity but it has associated with negative effects on humans because by the use of pesticides the concentration of pesticides significantly increased in food and in our environment. Millions of pesticide poisoning cases are found annually (Richter, 2002). Most of the pesticides travel long distances from their source of origin. Many of the birds species get exposed to these pesticides during traveling. When birds exposed to pesticides birds suffer by many problems like behavioural changes, endocrine dysfunction, immune disfunction, birth defects, cancers, reproductive dysfunction etc. (Orris et al., 2000). Pesticides are lethal when its concentration is very high and cause density-mediated indirect effects (Fleeger et al., 2003). It can change the function of hormones, neurotransmitters, physiology, morphology and behaviour at sub-lethal concentrations (Abrams, 1995).

Carbaryl is a member of carbamate pesticide.Chemically carbaryl is 1-naphthalenyl methylcarbamate which is consists of a naphthalene ring and methylcarbamate (-OCO-NH-CH3).

illustration not visible in this excerpt

Fig. 1. Chemical Structure of Carbaryl ( Source: ChemEssen.com)

Carbaryl has been registered for use in more than 400 types of application and it is used as insecticide since 1959 (U.S. EPA/OPP 2004a). Carbaryl is the first carbamate insecticide which acts on nervous system in insects by blocking acetylcholine. Carbaryl is degraded in water by light, pH and temperature. carbaryl also degraded in soil by some microbial actions, hydrolysis and photolysis (Mount and Oehme, 1981; TOXNET, 1988). The U.S. Department of Agriculture uses carbaryl in forests to control various insects which causes severe damage.

Carbaryl is widely used in the poultry industry to protect from diseases and some insects like ticks and mites. Some of these pests have also been shown to be capable of transmitting leucosis a disease of poultry (Draper, 1967). Carbaryl inhibit the acetylcholinesterase (AChE) activity in vertebrates, insects and human beings. Acetylcholinesterase is the important enzyme of nervous system which plays important role in breaking down acetylcholine (Ach) found in nervous system of insects and mammals (WHO, 1994d). Carbaryl control the pest by inhibiting the acetylcholinesterase activity but carbaryl also posses risks to some non-targeted animals like humans. Carbaryl can penetrate into the body by skin, respiratory tract and gastrointestinal tract (Dorough and Casida, 1964; Fukuto, 1972).

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Figure 2: Mode of Action of Carbamate Insecticide

Author ’ s own work

Various pesticides causes eggshell thinning, reduced hatching and reduced fertility in various bird species such as eastern screech-owls (Otusasio) and American Kestrels (Falco spar-veruis) (Clark et al., 1995; MacLellan et al., 1996). Due to reduced level of anticholinesterase detoxifying enzymes, birds are more sensitive to acute exposure to such types of pesticides (Parker and Goldstein, 2000). Carbamate pesticides are more rapidly bind to AChE of birds than other vertebrates due to high activity of AChE in the brain of birds (Westlake et al., 1983; Hill, 1992).

Daily acceptable intake (ADI) of carbaryl in water was established by Food and Agriculture Organisation (FAO) and World Health Organisation (WHO) (FAO/WHO, 1975; Wills et al., 1968) as 0.01 mg/kg bw per day for humans and 10 mg/kg bw per day for rats (Carpenter et al., 1961). Maximum acceptable concentrations (MAC) for carbaryl in water may be calculated by the formula:

MAC = 0.01 mg/kg bw per day× 70 kg bw × 0.20 ∼ 0.09 mg/L

1.5 L/d

Where:

- ADI established by the FAO and WHO: 0.01 mg/kg bw
- Average body weight of adult: 70 kg
- Proportion of daily intake of carbaryl in water: 0.20
- Average daily consumption of water by adult: 1.5 L/d

Chickens are vulnerable to carbaryl toxicity because poultry houses and birds are dusted with this pesticide. Such exposure of poultry to chemical pesticide causes various health consequences to poultry birds which causes great economic loss and also posing potential threat to public health due to presence of pesticides residues in poultry meat. The use of pesticides on crops, storehouses, poultry houses and non-judicious application for spraying animals to prevent ectoparasites leaves residues which causes serious health effects to both animals and humans (Pal and Kushwah, 1990, 2000).

Some heavy metals such as iron, copper, magnesium and zinc are essential for growth of broiler chicks. It is also involved in many physiological processes, digestive and biosynthetic processes in the body. heavy metals primarily function as a catalyst in various enzyme systems in the body cells. Such heavy metals are supplemented in the form of sulphates, bicarbonates, and oxides. The primary role of zinc in the body is to make the association of enzyme and proteins to form enzyme-protein molecule which act as an activator (Bales et al., 1994).

Zinc is nutritionally essential for body, deficiency of zinc results in many severe health consequences. Zinc is present in most of the foodstuffs, air and water. In the atmosphere level of zinc increased by industries. Suggested limit of daily intake of zinc is approximately 12 to 15 mg per day from food. Zinc toxicity have been reported by following ingestion of beverages which are kept in galvanized cans which leads to gastrointestinal distress, diarrhoea, hematologic, hepatic or renal toxicity in humans, but teratogenic and carcinogenic toxicity was observed in animals (Goyer, 1991; Furst, 1984; Leonard et al., 1986; Rogers, 1996). Absorption of zinc is a carrier-mediated process which is controlled homeostatically, about 20 to 30 percent of ingested zinc is absorbed by this process (Davies, 1980).

Table 1: Recommended Dietary Allowances (RDA) of Zinc by different Age groups and Gender

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Source: IOM 2002

Zinc plays various important functions in humans such as:

- Protein synthesis
- Energy metabolism
- Vitamin A metabolism
- Synaptogenesis, Neurogenesis and Neuronal growth
- Release and storage of Insulin
- Cellular division
- DNA repair and metabolism
- Cell differentiation, proliferation and apoptosis of cell
- Spermatogenesis

Chapter Two

Toxicological profile of carbaryl

Carbamate insecticides are solids and poorly soluble in water. Acute poisoning of carbamate is less frequent. Carbaryl is the most toxic carbamate insecticide which is embryotoxic, cardiotoxic, hepatotoxic, teratogenic and carcinogenic effects (White-Stevens, 1977; Farage-Elawar, 1990; Farage-Elawar and Blaker, 1992; Shukla et al., 1992).Neurotoxic effects of carbaryl involves synapses which chemically transfer impulses through cholinesterase. Severity of exposure of pesticides and its toxic effects depend on:

- Dose
- Routes of exposure i.e., direct or indirect
- Types of effects of pesticides and its metabolites
- Health status of the individual
- Accumulation in the body
- Persistence in the body

Table 2: Values of Acute LD50 0f Carbaryl for various Birds species

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Source: www.sera-inc.com

Carbaryl inhibits cholinesterase which alters neural conductivity. Such type of neurotoxins are very much toxic to exothermic animals, since they have evolved no such mechanism and their nerve cells are constantly excited which leads to death (Alloway and Ayres, 1999). Biochemical basis of toxicity of carbaryl and other inhibitors of AChE activity is directly related to the function of AChE. Neural impulses transmitted between nerve cells and effector cells by acetylcholine in the cholinergic system. Receptor cells stimulated when acetylcholine reaches its certain level. When carbaryl enters in the body it inhibits the AChE activity and acetylcholine persists and continues to accumulate at the synapse- it is the space between two cells. Accumulation of acetylcholine initially cause continuous stimulation of cholinergic system which may followed by paralysis due to cell fatigue. Some researchers reported oral intoxication in white leghorn chickens (Gallus gallus domesticus) when treated with 500mg/kg/day of bromacil a herbicide and 1000mg/kg/day of bromacil to mallard ducks (Anas platyrhynchos) (Palmer u. Radeleff, 1969; Washington State Department of Transportation, 2006).

Table 3: Different carbamate pesticides with their toxicity level

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Source: IPCS, 1986

Birds are very sensitive to neurotoxic compounds such as carbamates and organophosphates because they are cholinesterase inhibitors, fipronil (GABA-R inhibitor), Indoxacarb (sodium channel blocker), and Dithiols (nACh-R inhibitor).There are 50% of documented cases of pesticide poisoning in birds are caused by carbamate and organophosphate pesticide reported by the U.S. Department of Interior’s National Wildlife Health Centre (Madison, 1993). Such type of poisoning in birds are caused due to consumption of seeds and contaminated insects because they contain lethal amount of insecticides on their surface (Prosser and Hart, 2005). Toxicity of pesticides influenced by some environmental factors such as temperature.

Table 4: Effect of Carbaryl on Various Birds Species

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Source: www.sera-inc.com

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