eChapters

Key facts
    
•    Dioxins are the most dangerous and ‘super toxic’ chemicals so far known on the earth and three closely related families are collectively known as dioxins. These are Polychlorinated dibenzo-p-dioxin or dioxins (PCDDs), Polychlorinated dibenzofurans or furans (PCDFs) and polychlorinated biphenyls (PCBs).
    
•    2, 3, 7, 8-TCDD (or called TCDD) is the most potent of all the congeners. The toxicity equivalency factor or TEF of TCDD has been assigned as 1, while all other congeners assigned in order of toxicity ranking magnitude relative to TCDD.
    
•    There are 75 compounds/congeners in the dioxin family (PCDD), 135 compounds in the furan family (PCDF) and 209 possible compounds in the PCBs based on the possible number of chlorine atoms.
    
•    The toxicity of dioxins and dioxin-like compounds vary substantially among the different PCDDs, PCDFs and PCBs. It is generally accepted that only 29 out of the 419 congeners of dibenzo-p-dioxins, dibenzofurans and polychlorinated biphenyls are toxic to humans and other organisms. The TCDD is most toxic and registered by the WHO as carcinogenic for humans.

Key facts

    
•    Endocrine disrupting chemicals (EDCs) are micropollutants with estrogenic or androgenic activities at very low concentrations and are emerging as a major concern for water quality.
    
•    EDCs include natural and synthetic hormones (Estrone or E1, 17b-estradiol or E2, Estriol or E3, 17a-ethynylestradiol or EE2); alkylphenols (nonylphenol or NP; octyphenol or OP), phenols (bisphenol-A or BPA), phthalates (Di-n-butyl phthalate or DBP, Di-2-(ethylhexyl)-phthalate or DEHP); organotins (tributyltin or TBT); and phytoestrogens (b-sitosterol, coumestrols, genistein). 
    
•    Wastewater treatment plants, intensive livestock effluents, industrial wastewaters, landfill, paper and pulp mill effluents and antifouling paints are important sources of EDCs in the environment.

Key facts
    
•    Pesticides are chemicals that are broadly used to protect crops, livestock and other animals and plants from pests and diseases. They are classified according to the type of pest to be controlled (algicides, herbicides, fungicides and insecticides).
    
•    Commercial production of DDT began in 1943. At that time, DDT was considered to be a wonderful invention. It was cheap to produce, very toxic to insects and much less toxic to mammals and its usage resulted in a sharp decline of mosquito borne diseases. In 1962, it was discovered that DDT was causing egg-shell thinning in bird eggs and thus was leading to the near extinction of bird species such as peregrine falcons and bald eagles.
    
•    Pesticides use has greatly helped to increase and improve the world food production. Use of pesticides also increases farmer’s profits by preventing crop losses due to pest attacks and weed infestation.

Key facts
    
•    Biotoxins are naturally occurring toxic compounds produced by some freshwater cyanobacteria (blue-green algae) and marine algal species (dinoflagellates, diatoms).
    
•    Tonnes of pharmacologically active substances are used annually in human and veterinary medicines, some of these substances are excreted (human and animal) non-metabolised or an active metabolites and enter into the environment since waste water treatment plant (WWTP) cannot degrade them.
    
•    In Europe, around 4,000 different pharmaceutically active compounds are used as human and veterinary drugs and the annual consumption is about several hundred tonnes.
    
•    European Union and the United States laws require an assessment of potential risks to the environment as part of license application processes for new medicinal products.

•    Pharmaceutical products are generally polar, water soluble and low volatile molecules, it means that they have high mobility in the environment.

Key Facts

    •    The heavy metals (HM) or trace metals in an aquatic environment can come from natural (e.g. geological minerals, wind blown silicate dust, volcanic emissions, sea spray and combustion) and anthropogenic sources (e.g. mining, industry and sewage treatment discharges as well as electronic waste and agriculture fertilisers). In aquatic systems, the heavy metals of greatest concerns are cadmium, copper, lead, mercury and zinc.
    •    Metals may exist in a number of physico-chemical states in aqueous systems such as particulate matter and dissolved forms. Metal speciation in freshwater is strongly influenced by hardness, alkalinity, pH, natural dissolved organic matter (DOM) and redox potential. 
    •    Water hardness is quantitatively related to metal toxicity in freshwater (i.e. toxicity of heavy metals decrease with increasing hardness and alkalinity; on the other hand, toxicity increases with decreasing salinity, dissolved organic matter and chelators). The uptake and toxicity of heavy metals of most metals in marine waters is low as compared to freshwater because metals are easily complexed with chloride ions.
    •    The toxicity of HMs is related to the dissolved ionic form of the metal rather than total concentration of the metal. Each different physico-chemical forms of an element has a different toxicity, for example, if the element (e.g. Cu) is absorbed on a colloidal particles it is expected to be of little or no effect on aquatic organisms, however,  if the copper is available as free Cu (II) ion, few aquatic organisms may survive.

INTRODUCTION

The use of chemical for protecting plants from the ravages of the pathogens is not an innovation of the 20th century. Chemicals have been used for over 200 years to protect plants against fungal diseases. At present about 150 chemicals belonging to different classes are used as fungicides in world agriculture. Most of the recommended treatments generally provide 90% or greater control of target diseses. Even when a crop has been grown from pathogen free soil and the crop seems superficially healthy, the use of fungicides in some circumstances become unavoidable. Resistant varieties of potato are attacked by late blight if rain occurs during tuber formation. To control this disease use of fungicides become vital to avoid any loss of the crop. Thus, even in the case of resistant varieties, judicious use of chemical protection will extend the life of resistance in the variety. For killing different groups of pathogens, different types of chemicals are required. The chemicals mainly used for controlling diseases are: fungicides for killing fungus, bactericide for killing barteria, nematicides for killing nematodes, and viricides for killing viruses.

Anti-pathogen Chemicals
The chemical substances that help to retard the activity of pathogens like fungus, bacteria and nematodes are said to be anti-pathogen chemicals.
Aim of use of chemicals in plant disease control
The aim and of use of chemicals in plant disease control are
• To create a toxic barrier between the host surface or tissue and the pathogen .
• To eradicate the pathogen present at a particular site on the host, such as seed, foliage, roots etc.
Functions of chemicals in plant disease control
• Reduction in inoculum density or eradication of inoculum from source of growth, multiplication and survival.
• Inactivaion or destruction of the pathogen when it lands on the treated surface, and
• Cure of the diseased plant.

Introduction and Concept

The word fungicide has originated from two Latin words: viz. fungus and caedo (to kill). So literally, a fungicide would be any physical or chemical agency which kills a fungus. However, the word is restricted to chemicals. Hence, the word fungicide should mean a chemical capable of killing fungi. However, there are a number of compounds which do not kill the fungus. They simply inhibit growth or spore germination temporarily. If the fungus is freed from such substances, it would revive. Such a chemical is called a fungistat. and the phenomenon as fungistasis. Some other chemicals, like certain phenantherene derivatives and bordeaux mixture may inhibit spore production without affecting vegetative growth. These are called antisporulants. There are other groups of chemicals which exhibit very poor or no antifungal activity in vitro condition but provide protection to the plants either by inhibiting the penetration of host surface by the fungi or by inducing the host defense system. The former type of chemicals are termed as antipenetrants and later as antipathic agents. Even though fungistats, antisporulants, antipenentrants, and antipathic agents do not kill fungi, they are included under the broad term fungicide because by common usage, the word fungicide has been defined as chemical substance which has ability to prevent damage caused by fungi to plants and their products. Fungicide which is effective only if applied prior to fungal infection is called protectants. On the other hand, fungicide which is capable of eradicating a fungus after it has caused infection, and thereby curing the plant, is called therapeutant.

Introduction

The metal particles in nanometer scale shows exciting optical and electronic characteristics when compared with respective bulk metals. Because of the inherent electronic properties of the metal and metal oxide nanoparticles these nanostructure materials are applied in various disciplines in recent days. Mostly these nanoparticles can be synthesized either top down or bottom up approaches. The conversion of bigger size particle or matter into tiny particles is called top down approach where as smaller particles or atoms joined together forming particles in regular shape within nanometer scale dimension is called bottom up approach. The formation of nanoparticles by chemical reduction is an example for the later one and the reduction size with the help of mechanical crusing leads to the formation of fine nanoparticles is named as top down approach. Mostly nanoparticles can be synthesized by chemical method because of its easiness to synthesis particles with uniform size and high purity.

In the previous chapter the physical methods of fruit and vegetables processing and preservation have been discussed. The present chapter deals with chemical method of fruit and vegetable preservation. In this method of preservation of fruits and vegetables, chemicals as preservatives are used to prevent the spoilage of fruit and vegetable products. These preservatives react with food (produce) constituents or microorganisms and create unfavourable conditions which hinder growth, activities and multiplication of microbes responsible for spoilage of food products. These chemical agents have maximum permissible limit of their use as law. They can be classified into two classes class I and class II.

Class I: Sugar, Salt and Oils

Class II: Sodium benzoate, Potassium metabisulphite (K M S) and Sorbic acid

Chemical synthesis is spontaneous organization of molecules into stable, structurally well-defined aggregates at the nanometer length scale. Chemical synthesis is largely an art form (i.e., theory often does not quantitatively predict how to make new materials from molecules).Yet, chemical synthesis can be quite powerful (e.g., proteins and complex organic molecules can be made from simple reagents) Semiconductor nanocrystals have been synthesized via “natural self-assembly” in two steps:

1.Capped cluster molecule forms spontaneously from molecular reagents in solution

2.Cluster molecules crystallize out of solution

18.1 Introduction

Recycling of industrial wastewater is not only environmentally beneficial, but it is typically more cost effective than conventional treatment and discharge. Through application of stream segregation and appropriate treatment technologies, high purity water is produced for continuous reuse where by metals are recovered and solid wastes reduced. Recycling of industrial effluent by chemical treatment includes many separation methods for getting pure waters. It is very essential to discuss about reverse osmosis, filtration, adsorption evaporation etc. This chapter includes the discussion about the methodology of chemical treatments.

18.2 Conventional Treatments

The oldest and most widely applied method of wastewater treatment involves the addition of chemicals and applications of aerators etc. to alter the make-up constituents of a waste. Although generally downsized, the process continues to play an important role in newer systems used today. Automated controls and advanced instrumentation have improved this technology in recent years. (Tomer et.al., 1997)

Introduction

Packaging of food material is an essential component of food industry since packaging provides protection, physical tampering resistance and unique appearance to the food products which attracts the customers (Robertson, 2006). The handling of food products would be inefficient and costly if they are not packed properly (Robertson, 2006). The style and design of packaging influence their sale as well as demand. The main aim of packaging is to corroborate the safety and quality of food by preventing microbial contamination (Lee K.M, 2010). Plastics, papers, glass and metals are the common materials used for packaging of food products (Arvanitoyannis and Bosnea, 2004). Among these plastics are most commonly used packaging material because of their low cost, light weight, design freedom and high durability (British Plastic Federation). Various additives are added to the plastics to achieve desired physical and chemical properties. These additives are stabilizers, plasticisers, lubricants and f lame retardants. These additives have potential to transfer from the packaging materials to the food stuffs(K Bunia et al., 2013).

The efficient food packaging solutions are the need of the hour for the Earth. The food losses including the production, post harvest, processing stages of the supply chain and food wastage includes loss of edible food occurring at the f inal stages of food chain that is during retail supply or ultimate consumption. The food born illnesses cannot be ignored which are a consequence of the contamination of food by bacteria, viruses, parasites, new chemical entities or toxicants. We need to optimise the food supply chain, increase food shelf life and consciousness amidst food producers to food consumers. The active and intelligent packaging may help the globe through sufficient food for the increasing population. Scavengers/ absorbers are important solutions which may absorb substances from the packaging inner atmosphere (ethylene absorbers, oxygen scavengers; emitters and antioxidants).

Nematodes are multicellular, unsegmented, bilaterally symmetrical roundworms belonging to pseudocoelomates class of creatures. Many of them are parasites of plants. Different crops species are susceptible to several species of plant parasitic nematodes which limits the yield and quality of the food harvest. Root-knot nematodes (Meloidogyne spp.), foliar nematodes (Aphelenchoides spp.), root-lesion nematodes (Pratylenchus spp.) reniform nematodes (Rotylenchulus spp.) and other ectoparasitic nematodes are the important nematodes species to infect the crop plants.

Weeds can be defined as plants which are undesirable, persistent, damaging and interfere with growth of other crop plants thus affecting agriculture, natural resources and economy of the country. These plants influence the produce of farmers in several ways.

It is used in the control of bacterial leaf spots, blights, and cankers mostly on fruits crops and ornamentals. The Bordeaux mixture, however, can cause burning of leaves or russeting of fruit such as apples when applied in cool, wet weather. The phytotoxicity of Bordeaux is reduced by increasing the ratio of hydrated lime to copper sulfate. Copper is the only ingredient in the Bordeaux mixture that is toxic to pathogens and, sometimes, to plants, whereas the role of lime is primarily that of a “safener.”

The algae associated with the plants belongs to the Order Trentepohliales (Ulvophyceae, Chlorophyta). These are filamentous green algae parasitic to higher plants, generally causing minor diseases characterized by negligible leaf spots, but on certain crops, in moist environments, these algal diseases can cause economic injury to plant leaves, fruits, and stems (Nelson, 2008).

Plant viruses cause severe crop losses worldwide. Conventional control strategies, such as cultural methods and biocide applications have limited success at mitigating the impact of plant viruses.

Introduction

The mammary glands of female mammals secrete milk, a necessary food that is liquid and meets the newborn’s nutritional needs. All mammals consider milk to be a complete food for their newborns. It is considered a necessary food for humans and can be consumed as a product or as liquid milk. It contains almost all essential nutrients except iron, which is very low in milk. In essence, milk is an emulsion of protein and fat in water, supplemented with carbohydrates, vitamins, and minerals.

Definition of Milk

• Milk is a complex biological fluid that differs from species to species in both composition and physical properties. It is the full lacteal secretion of a mammary gland that is obtained by milking mammals for a minimum of 72 h after calving or until the milk is free from colostrum.

• FSSAI defines milk as the normal mammary secretion derived from the complete milking of healthy milch animals. It should be free from colostrum.

From a chemical perspective, milk is a dynamically balanced mixture that comes in different forms such as emulsion, colloidal suspension, and true solution. It also contains varying amounts of proteins, fats, carbohydrates, salts, and water.

Gross Composition of Milk

Milk composition varies among different mammals. The average chemical composition of milk in various species is given in Table 1. Buffalo milk and sheep milk contain higher amounts of fat, while human milk comparatively has the highest lactose content. Human milk has lower protein content as compared to milk of other species.

Sixteen chemical elements are known to be important for a plant growth, their metabolic activities and survival. These can be divided in to two main groups