A risk is the probability of suffering harm from a hazard that can cause injury, disease, death, economic loss, or damage.
Probability—a mathematical statement about the likelihood that harm will be suffered from a hazard.
“The lifetime probability of developing lung cancer from smoking one pack of cigarettes per day is 1 in 250.” This means that 1 of every 250 people who smoke a pack of cigarettes every day will likely develop lung cancer over a typical lifetime
1. Plants are exposed to various stresses from both human activities and natural causes that can increase the production of reactive oxygen species (ROS) in plant tissues.
2. ROS are generated during normal plant metabolic processes and photosynthesis, but stress situations increase their toxic production.
3. Plants have developed complex antioxidant defense systems using enzymatic and non-enzymatic components like ascorbate, glutathione, phenolics and antioxidant enzymes to scavenge ROS and protect against oxidative damage.
Plants have evolved chemical defenses like proteinase inhibitors and toxic compounds to protect themselves from damage. Jasmonic acid (JA) is a key signaling compound that induces these defenses. JA is synthesized from linolenic acid through the octadecanoid pathway. It regulates processes like growth, photosynthesis, and defense. JA signaling involves peptide signals like systemin and leads to both local and systemic responses in plants.
Wind as an Ecological Factor by Salman SaeedSalman Saeed
Wind as an Ecological Factor lecture for Biology, Botany, Zoology, and Chemistry Students by Salman Saeed lecturer Botany University College of Management and Sciences Khanewal, Pakistan.
About Author: Salman Saeed
Qualification: M.SC (Botany), M. Phil (Biotechnology) from BZU Multan.
M. Ed & B. Ed from GCU Faisalabad, Pakistan.
This document classifies and describes different divisions of algae. It discusses five main divisions: Chlorophyta, Euglenophyta, Pyrrophyta, Chrysophyta, and Cyanophyta. For each division, it outlines their characteristic classes, orders, pigments, food reserves, thallus structure, and modes of reproduction. Key examples are provided for representative orders within each division. The classification system serves to organize the wide diversity of algal types based on their shared morphological and physiological traits.
- Green algae are thought to be the ancestors of modern plants. They may have lived on land over 500 million years ago.
- Plants evolved adaptations like roots, leaves, and vascular tissue to survive on land. They obtain water and minerals from roots and CO2 from the air through leaves.
- Plants have alternation of generations, where the haploid gametophyte produces gametes and the diploid sporophyte produces spores through meiosis. This life cycle is seen in mosses, ferns, and seed plants.
This document discusses various types of plant movements, including:
- Hygroscopic movements that occur due to gain or loss of water
- Vital movements like nutation, circumnutation, hyponasty and epinasty that involve differential growth
- Turgor movements seen in plants like Mimosa pudica that fold their leaves in response to touch
- Autonomous movements of locomotion including ciliary movements, amoeboid movement, and cyclosis
- Tactic movements involving responses to stimuli like phototaxis, chemotaxis, and thermotaxis
- Tropic movements including phototropism, gravitropism, and thigmotropism mediated by plant hormones
economic importance of gymnosperms.Gymnosperms are simple and primitive seed-bearing plants without flowers.
The plant body is sporophytic and is differentiated into root,stem and leaves.
All gymnosperms are usually wind-pollinated.
Leaves have thick cuticle and sunken stomata.
Gymnosperms are heterosporous.magasporangia and microsporangia occur on mega and microsporophylls respectively.
Anatomy of Reproductive Parts: Flower, Fruit,SeedFatima Ramay
A flower, sometimes known as a bloom or blossom, is the reproductive structure found in flowering plants (plants of the division Magnoliophyta, also called angiosperms). The biological function of a flower is to effect reproduction, usually by providing a mechanism for the union of sperm with eggs. Flowers may facilitate outcrossing (fusion of sperm and eggs from different individuals in a population) or allow selfing (fusion of sperm and egg from the same flower). Some flowers produce diaspores without fertilization (parthenocarpy). Flowers contain sporangia and are the site where gametophytes develop. Flowers give rise to fruit and seeds. Many flowers have evolved to be attractive to animals, so as to cause them to be vectors for the transfer of pollen.
Fruit anatomy is the internal structure of fruits.
Fruits are the mature ovary or ovaries of one or more flowers. In fleshy fruits, the outer layer (which is often edible) is the pericarp, which is the tissue that develops from the ovary wall of the flower and surrounds the seeds.
But in some seemingly pericarp fruits, the edible portion is not derived from the ovary. For example, in the fruit of the ackee tree the edible portion is an aril, and in the pineapple several tissues from the flower and stem are involved.
The outer covering of a seed is tough because the parent plant needs to protect the plant growing.
A seed is an embryonic plant enclosed in a protective outer covering known as the seed coat.
It is a characteristic of spermatophytes (gymnosperm and angiosperm plants) and the product of the ripened ovule which occurs after fertilization and some growth within the mother plant. The formation of the seed completes the process of reproduction in seed plants (started with the development of flowers and pollination), with the embryo developed from the zygote and the seed coat from the integuments of the ovule.
Seeds have been an important development in the reproduction and spread of gymnosperm and angiosperm plants.
1. Plants are exposed to various stresses from both human activities and natural causes that can increase the production of reactive oxygen species (ROS) in plant tissues.
2. ROS are generated during normal plant metabolic processes and photosynthesis, but stress situations increase their toxic production.
3. Plants have developed complex antioxidant defense systems using enzymatic and non-enzymatic components like ascorbate, glutathione, phenolics and antioxidant enzymes to scavenge ROS and protect against oxidative damage.
Plants have evolved chemical defenses like proteinase inhibitors and toxic compounds to protect themselves from damage. Jasmonic acid (JA) is a key signaling compound that induces these defenses. JA is synthesized from linolenic acid through the octadecanoid pathway. It regulates processes like growth, photosynthesis, and defense. JA signaling involves peptide signals like systemin and leads to both local and systemic responses in plants.
Wind as an Ecological Factor by Salman SaeedSalman Saeed
Wind as an Ecological Factor lecture for Biology, Botany, Zoology, and Chemistry Students by Salman Saeed lecturer Botany University College of Management and Sciences Khanewal, Pakistan.
About Author: Salman Saeed
Qualification: M.SC (Botany), M. Phil (Biotechnology) from BZU Multan.
M. Ed & B. Ed from GCU Faisalabad, Pakistan.
This document classifies and describes different divisions of algae. It discusses five main divisions: Chlorophyta, Euglenophyta, Pyrrophyta, Chrysophyta, and Cyanophyta. For each division, it outlines their characteristic classes, orders, pigments, food reserves, thallus structure, and modes of reproduction. Key examples are provided for representative orders within each division. The classification system serves to organize the wide diversity of algal types based on their shared morphological and physiological traits.
- Green algae are thought to be the ancestors of modern plants. They may have lived on land over 500 million years ago.
- Plants evolved adaptations like roots, leaves, and vascular tissue to survive on land. They obtain water and minerals from roots and CO2 from the air through leaves.
- Plants have alternation of generations, where the haploid gametophyte produces gametes and the diploid sporophyte produces spores through meiosis. This life cycle is seen in mosses, ferns, and seed plants.
This document discusses various types of plant movements, including:
- Hygroscopic movements that occur due to gain or loss of water
- Vital movements like nutation, circumnutation, hyponasty and epinasty that involve differential growth
- Turgor movements seen in plants like Mimosa pudica that fold their leaves in response to touch
- Autonomous movements of locomotion including ciliary movements, amoeboid movement, and cyclosis
- Tactic movements involving responses to stimuli like phototaxis, chemotaxis, and thermotaxis
- Tropic movements including phototropism, gravitropism, and thigmotropism mediated by plant hormones
economic importance of gymnosperms.Gymnosperms are simple and primitive seed-bearing plants without flowers.
The plant body is sporophytic and is differentiated into root,stem and leaves.
All gymnosperms are usually wind-pollinated.
Leaves have thick cuticle and sunken stomata.
Gymnosperms are heterosporous.magasporangia and microsporangia occur on mega and microsporophylls respectively.
Anatomy of Reproductive Parts: Flower, Fruit,SeedFatima Ramay
A flower, sometimes known as a bloom or blossom, is the reproductive structure found in flowering plants (plants of the division Magnoliophyta, also called angiosperms). The biological function of a flower is to effect reproduction, usually by providing a mechanism for the union of sperm with eggs. Flowers may facilitate outcrossing (fusion of sperm and eggs from different individuals in a population) or allow selfing (fusion of sperm and egg from the same flower). Some flowers produce diaspores without fertilization (parthenocarpy). Flowers contain sporangia and are the site where gametophytes develop. Flowers give rise to fruit and seeds. Many flowers have evolved to be attractive to animals, so as to cause them to be vectors for the transfer of pollen.
Fruit anatomy is the internal structure of fruits.
Fruits are the mature ovary or ovaries of one or more flowers. In fleshy fruits, the outer layer (which is often edible) is the pericarp, which is the tissue that develops from the ovary wall of the flower and surrounds the seeds.
But in some seemingly pericarp fruits, the edible portion is not derived from the ovary. For example, in the fruit of the ackee tree the edible portion is an aril, and in the pineapple several tissues from the flower and stem are involved.
The outer covering of a seed is tough because the parent plant needs to protect the plant growing.
A seed is an embryonic plant enclosed in a protective outer covering known as the seed coat.
It is a characteristic of spermatophytes (gymnosperm and angiosperm plants) and the product of the ripened ovule which occurs after fertilization and some growth within the mother plant. The formation of the seed completes the process of reproduction in seed plants (started with the development of flowers and pollination), with the embryo developed from the zygote and the seed coat from the integuments of the ovule.
Seeds have been an important development in the reproduction and spread of gymnosperm and angiosperm plants.
This document discusses auxin, the first discovered plant growth hormone. It describes auxin's role in plant development processes like stem elongation and root initiation. Indole-3-acetic acid was identified as the principal natural auxin. Auxin is synthesized in shoot and root apical meristems and transported polarly from cell to cell in a chemiosmotic process involving PIN and ABCB transporters. Auxin influences developmental processes like phototropism and gravitropism through redistribution mediated by these transporters. It acts as a signal in tropic responses and directs plant organogenesis through polar auxin transport streams.
This document provides a history of taxonomy from ancient times through the modern era. It discusses how early ancient Chinese, Egyptian, Greek, and Roman scholars began classifying and organizing plants and animals. Key early taxonomists mentioned include Aristotle, Theophrastus, Dioscorides, and Pliny. It then covers the contributions of later taxonomists like Caesalpino, the Bauhin brothers, John Ray, and Joseph Pitton de Tournefort. The era of Carl Linnaeus is described as revolutionizing taxonomy through his introduction of binomial nomenclature. The document outlines how Linnaeus helped transform botany and zoology into scientific disciplines. It concludes with a discussion of developments like cl
The document discusses the phenomenon of polyembryony in plants. It defines polyembryony as the occurrence of more than one embryo in a seed. Polyembryony is classified into true and false polyembryony. True polyembryony includes cleavage polyembryony, where embryos arise from egg cleavage or other embryo sac cells, and adventive polyembryony, where embryos arise from tissues outside the sac. False polyembryony results from multiple embryo sacs. Causes of polyembryony include the necrohormone theory of degenerating cells stimulating embryo formation and the hybridization theory of gene recombination enabling multiple embryos. Polyembryony has importance for plant breeding, propagation of
Presentation on Gymnosperms. Prepared by Rahmat Alam Puniyali, Student of BS IV at Karakoram International University Gilgit, Pakistan. Photos of related plants are taken by the creator at KIU (Karakoram International University) campus.
(Some of the pictures and diagrams are taken from the websites of their resembling organizations (The McGraw-Hill Companies))
Photorespiration - Introduction, why is it occur in plants, pathway of photorespiration, Enzymes names, pathway step by step explanation, Benefits of photorespiration, additional information related to photorespiration, Rubisco enzyme, Oxygenase enzyme, Oxygen concentration higher leads to photorespiration, problem to carry out calvin cycle.
Bioluminescence is the production and emission of light
from a living organism including some fungi belonging to Basidiomycotina and few fungi belonging to Ascomycotina
A hydrosere is a plant succession which occurs in an area of fresh water such as in oxbow lakes and kettle lakes.
Dr. K. Rama Rao
Govt. Degree College
TEKKALI; Srikakulam Dt. A. P
Phone: 9010705687
1. Gymnosperms are naked seeded non-flowering plants that show alternation of generations between sporophyte and gametophyte stages. The sporophyte plant body is well differentiated into roots, stems, and leaves while the gametophyte is greatly reduced.
2. Gymnosperms reproduce sexually through cones that contain either microsporangia or megasporangia. Pollination occurs and pollen tubes carry sperm to fertilize eggs within the ovules, forming seeds with embryos.
3. The life cycle involves microspores forming male gametophytes that produce sperm, and megaspores forming reduced female gametophytes containing eggs. Fertilization occurs
Leaf structure, adaptations, development Jasmine Brar
Leaves develop from leaf primordia in the shoot apical meristem. They have three main parts - the lamina, petiole, and leaf base. The lamina is the broad, typically green, photosynthetic part of the leaf. Leaves come in many shapes and sizes and have a variety of venation patterns and arrangements on the stem. Leaves also have many modified forms that take on additional functions like storage or reproduction.
Meiosis occurs in the megaspore mother cell and microspore mother cell to generate megaspores and microspores respectively. The microspores then undergo mitosis and develop protective outer layers, forming pollen grains. These grains contain sperm cells that can fertilize the female gametophyte within the pistil. The pollen tube grows through the pistil tissues guided by chemicals from the synergid cells within the embryo sac, and releases its contents including sperm for double fertilization of the egg and central cells.
The document summarizes key evolutionary tendencies in the kingdom Monera. It describes Monera as the oldest and simplest living organisms, including bacteria and cyanobacteria. Bacteria first evolved approximately 3.2-3.5 billion years ago, as evidenced by gene sequencing and ancient microfossils. Cyanobacteria were among the first organisms to evolve oxygenic photosynthesis approximately 2.45 billion years ago, introducing oxygen into the atmosphere. Actinomycetes are a group of bacteria that share characteristics with fungi and play an important role in decomposing organic materials in soil.
This document provides an overview of the classification of gymnosperms by different researchers over time. It discusses the key characteristics of modern gymnosperms and describes the four orders that living gymnosperms are commonly grouped into: Cycadales, Ginkgoales, Coniferales, and Gnetales. For each order, it highlights some representative genera and provides details on morphological features. The classification schemes of various scientists who studied gymnosperms, such as Bentham and Hooker, Engler, Coulter and Chamberlain, are summarized. Diagrams of their classification systems are also included.
This document discusses the key concepts and components of systematics, which includes taxonomy and phylogeny. It covers topics such as:
- The goal of phylogenetic reconstruction and evolutionary history.
- The major parts of systematics including description, classification, nomenclature, and identification.
- Tools for communicating taxonomic information such as keys and scientific names.
- Methods for determining evolutionary relationships including cladistics and cladograms.
- Principles of formal taxonomic naming and types of specimens.
- Uses of keys to identify unknown taxa.
1. The document discusses the origin and evolution of seeds from pre-ovules. It describes how seeds evolved from megasporangium through a series of steps including the formation of integument and micropyles.
2. Fossil structures from the Devonian and Carboniferous periods called pre-ovules provide evidence for the transition from naked megasporangium to ovules with fused integuments. These pre-ovules had unfused or partially fused integumentary lobes lacking a defined micropyle.
3. The degree of fusion of integumentary lobes in various fossil structures like Genomosperma, Physostoma and Stamnostoma demonstrate the progressive
This document summarizes the Bennettitales, a group of fossil plants that flourished during the Mesozoic era. It describes two families of Bennettitales: Bennettitaceae and Williamsoniaceae. Bennettitaceae had deeply sunk flowers on short, thick trunks, while Williamsoniaceae had fully exposed flowers on slender stems. The document provides details on the anatomy, reproduction, and classification of these two extinct families of seed plants.
This document discusses photosynthetic pigments and their role in photosynthesis. It explains that chlorophyll a is the primary pigment that absorbs sunlight to drive photosynthesis, while accessory pigments like chlorophyll b, carotenoids, xanthophylls, and anthocyanins absorb different wavelengths of light to enhance photosynthesis. These pigments are located in the chloroplast and work together to capture light energy which is converted to chemical energy and ultimately sugars through the process of photosynthesis.
Flower development is controlled by floral developmental genes that are induced in response to environmental signals like photoperiod and temperature. The ABC model describes how MADS-box transcription factors encoded by ABC genes control floral organ identity in four whorls. Class A genes specify sepals, Class B genes specify petals, Class C genes specify stamens, and the combination of B and C genes specify carpels. Mutations in these ABC genes result in homeotic transformations of floral organs. The ABC model was later expanded to the ABCDE model with the addition of SEPALLATA genes that act redundantly with ABC genes.
BIO CHEMICAL AND MOLECULAR BASIS OF POLLEN GERMINATIONadithyaguntha51
The document discusses the biochemical and molecular basis of pollen germination. It begins with an introduction to pollen structure and the stages of pollen development. It then discusses key factors that regulate pollen germination, including hydration, calcium and potassium signaling, and protein synthesis. The document analyzes several case studies that investigate specific genes and proteins involved in pollen germination, tube growth, and cell wall development using techniques like fluorescence microscopy, RNA analysis, and electron microscopy. The conclusion emphasizes that understanding pollen biology at the biochemical and molecular level can help overcome barriers to hybridization and broaden the gene pool for plant breeding.
This document discusses several methods for measuring the rate of photosynthesis, including dry matter accumulation, gas exchange via manometric or CO2/O2 exchange methods, and fluorescence techniques using chlorophyll, bacteria, or dyes. The gas exchange method is most commonly used today due to advantages like ability to measure leaves, plants, or forests and monitor changes frequently. Fluorescence of chlorophyll or dyes can also provide measurements but cameras are now used to create images showing fluorescence across samples.
Ch 14 short version directly from 14th New Edition saved 14 Feb 2012 and 15 A...BeamNation
The document discusses major health hazards, including biological, chemical, natural, cultural, and lifestyle risks. It describes how infectious diseases spread between people and the ways pathogens can enter the human body. The largest infectious disease killers are pneumonia/flu, HIV/AIDS, diarrheal diseases, tuberculosis, and malaria. Chemical hazards like carcinogens, mutagens, and teratogens are also discussed. Many chemicals can affect the immune, nervous, and endocrine systems. Risks are evaluated through toxicity testing and dose-response analysis. People are generally poor at evaluating risks objectively. Reducing poverty, practicing safe habits, and making informed choices can help reduce health risks.
This document discusses auxin, the first discovered plant growth hormone. It describes auxin's role in plant development processes like stem elongation and root initiation. Indole-3-acetic acid was identified as the principal natural auxin. Auxin is synthesized in shoot and root apical meristems and transported polarly from cell to cell in a chemiosmotic process involving PIN and ABCB transporters. Auxin influences developmental processes like phototropism and gravitropism through redistribution mediated by these transporters. It acts as a signal in tropic responses and directs plant organogenesis through polar auxin transport streams.
This document provides a history of taxonomy from ancient times through the modern era. It discusses how early ancient Chinese, Egyptian, Greek, and Roman scholars began classifying and organizing plants and animals. Key early taxonomists mentioned include Aristotle, Theophrastus, Dioscorides, and Pliny. It then covers the contributions of later taxonomists like Caesalpino, the Bauhin brothers, John Ray, and Joseph Pitton de Tournefort. The era of Carl Linnaeus is described as revolutionizing taxonomy through his introduction of binomial nomenclature. The document outlines how Linnaeus helped transform botany and zoology into scientific disciplines. It concludes with a discussion of developments like cl
The document discusses the phenomenon of polyembryony in plants. It defines polyembryony as the occurrence of more than one embryo in a seed. Polyembryony is classified into true and false polyembryony. True polyembryony includes cleavage polyembryony, where embryos arise from egg cleavage or other embryo sac cells, and adventive polyembryony, where embryos arise from tissues outside the sac. False polyembryony results from multiple embryo sacs. Causes of polyembryony include the necrohormone theory of degenerating cells stimulating embryo formation and the hybridization theory of gene recombination enabling multiple embryos. Polyembryony has importance for plant breeding, propagation of
Presentation on Gymnosperms. Prepared by Rahmat Alam Puniyali, Student of BS IV at Karakoram International University Gilgit, Pakistan. Photos of related plants are taken by the creator at KIU (Karakoram International University) campus.
(Some of the pictures and diagrams are taken from the websites of their resembling organizations (The McGraw-Hill Companies))
Photorespiration - Introduction, why is it occur in plants, pathway of photorespiration, Enzymes names, pathway step by step explanation, Benefits of photorespiration, additional information related to photorespiration, Rubisco enzyme, Oxygenase enzyme, Oxygen concentration higher leads to photorespiration, problem to carry out calvin cycle.
Bioluminescence is the production and emission of light
from a living organism including some fungi belonging to Basidiomycotina and few fungi belonging to Ascomycotina
A hydrosere is a plant succession which occurs in an area of fresh water such as in oxbow lakes and kettle lakes.
Dr. K. Rama Rao
Govt. Degree College
TEKKALI; Srikakulam Dt. A. P
Phone: 9010705687
1. Gymnosperms are naked seeded non-flowering plants that show alternation of generations between sporophyte and gametophyte stages. The sporophyte plant body is well differentiated into roots, stems, and leaves while the gametophyte is greatly reduced.
2. Gymnosperms reproduce sexually through cones that contain either microsporangia or megasporangia. Pollination occurs and pollen tubes carry sperm to fertilize eggs within the ovules, forming seeds with embryos.
3. The life cycle involves microspores forming male gametophytes that produce sperm, and megaspores forming reduced female gametophytes containing eggs. Fertilization occurs
Leaf structure, adaptations, development Jasmine Brar
Leaves develop from leaf primordia in the shoot apical meristem. They have three main parts - the lamina, petiole, and leaf base. The lamina is the broad, typically green, photosynthetic part of the leaf. Leaves come in many shapes and sizes and have a variety of venation patterns and arrangements on the stem. Leaves also have many modified forms that take on additional functions like storage or reproduction.
Meiosis occurs in the megaspore mother cell and microspore mother cell to generate megaspores and microspores respectively. The microspores then undergo mitosis and develop protective outer layers, forming pollen grains. These grains contain sperm cells that can fertilize the female gametophyte within the pistil. The pollen tube grows through the pistil tissues guided by chemicals from the synergid cells within the embryo sac, and releases its contents including sperm for double fertilization of the egg and central cells.
The document summarizes key evolutionary tendencies in the kingdom Monera. It describes Monera as the oldest and simplest living organisms, including bacteria and cyanobacteria. Bacteria first evolved approximately 3.2-3.5 billion years ago, as evidenced by gene sequencing and ancient microfossils. Cyanobacteria were among the first organisms to evolve oxygenic photosynthesis approximately 2.45 billion years ago, introducing oxygen into the atmosphere. Actinomycetes are a group of bacteria that share characteristics with fungi and play an important role in decomposing organic materials in soil.
This document provides an overview of the classification of gymnosperms by different researchers over time. It discusses the key characteristics of modern gymnosperms and describes the four orders that living gymnosperms are commonly grouped into: Cycadales, Ginkgoales, Coniferales, and Gnetales. For each order, it highlights some representative genera and provides details on morphological features. The classification schemes of various scientists who studied gymnosperms, such as Bentham and Hooker, Engler, Coulter and Chamberlain, are summarized. Diagrams of their classification systems are also included.
This document discusses the key concepts and components of systematics, which includes taxonomy and phylogeny. It covers topics such as:
- The goal of phylogenetic reconstruction and evolutionary history.
- The major parts of systematics including description, classification, nomenclature, and identification.
- Tools for communicating taxonomic information such as keys and scientific names.
- Methods for determining evolutionary relationships including cladistics and cladograms.
- Principles of formal taxonomic naming and types of specimens.
- Uses of keys to identify unknown taxa.
1. The document discusses the origin and evolution of seeds from pre-ovules. It describes how seeds evolved from megasporangium through a series of steps including the formation of integument and micropyles.
2. Fossil structures from the Devonian and Carboniferous periods called pre-ovules provide evidence for the transition from naked megasporangium to ovules with fused integuments. These pre-ovules had unfused or partially fused integumentary lobes lacking a defined micropyle.
3. The degree of fusion of integumentary lobes in various fossil structures like Genomosperma, Physostoma and Stamnostoma demonstrate the progressive
This document summarizes the Bennettitales, a group of fossil plants that flourished during the Mesozoic era. It describes two families of Bennettitales: Bennettitaceae and Williamsoniaceae. Bennettitaceae had deeply sunk flowers on short, thick trunks, while Williamsoniaceae had fully exposed flowers on slender stems. The document provides details on the anatomy, reproduction, and classification of these two extinct families of seed plants.
This document discusses photosynthetic pigments and their role in photosynthesis. It explains that chlorophyll a is the primary pigment that absorbs sunlight to drive photosynthesis, while accessory pigments like chlorophyll b, carotenoids, xanthophylls, and anthocyanins absorb different wavelengths of light to enhance photosynthesis. These pigments are located in the chloroplast and work together to capture light energy which is converted to chemical energy and ultimately sugars through the process of photosynthesis.
Flower development is controlled by floral developmental genes that are induced in response to environmental signals like photoperiod and temperature. The ABC model describes how MADS-box transcription factors encoded by ABC genes control floral organ identity in four whorls. Class A genes specify sepals, Class B genes specify petals, Class C genes specify stamens, and the combination of B and C genes specify carpels. Mutations in these ABC genes result in homeotic transformations of floral organs. The ABC model was later expanded to the ABCDE model with the addition of SEPALLATA genes that act redundantly with ABC genes.
BIO CHEMICAL AND MOLECULAR BASIS OF POLLEN GERMINATIONadithyaguntha51
The document discusses the biochemical and molecular basis of pollen germination. It begins with an introduction to pollen structure and the stages of pollen development. It then discusses key factors that regulate pollen germination, including hydration, calcium and potassium signaling, and protein synthesis. The document analyzes several case studies that investigate specific genes and proteins involved in pollen germination, tube growth, and cell wall development using techniques like fluorescence microscopy, RNA analysis, and electron microscopy. The conclusion emphasizes that understanding pollen biology at the biochemical and molecular level can help overcome barriers to hybridization and broaden the gene pool for plant breeding.
This document discusses several methods for measuring the rate of photosynthesis, including dry matter accumulation, gas exchange via manometric or CO2/O2 exchange methods, and fluorescence techniques using chlorophyll, bacteria, or dyes. The gas exchange method is most commonly used today due to advantages like ability to measure leaves, plants, or forests and monitor changes frequently. Fluorescence of chlorophyll or dyes can also provide measurements but cameras are now used to create images showing fluorescence across samples.
Ch 14 short version directly from 14th New Edition saved 14 Feb 2012 and 15 A...BeamNation
The document discusses major health hazards, including biological, chemical, natural, cultural, and lifestyle risks. It describes how infectious diseases spread between people and the ways pathogens can enter the human body. The largest infectious disease killers are pneumonia/flu, HIV/AIDS, diarrheal diseases, tuberculosis, and malaria. Chemical hazards like carcinogens, mutagens, and teratogens are also discussed. Many chemicals can affect the immune, nervous, and endocrine systems. Risks are evaluated through toxicity testing and dose-response analysis. People are generally poor at evaluating risks objectively. Reducing poverty, practicing safe habits, and making informed choices can help reduce health risks.
This document provides an outline of key topics in environmental health and toxicology, including: infectious diseases and emerging pathogens; antibiotic and pesticide resistance; the movement, distribution, and effects of toxins; and approaches to minimizing toxic impacts and assessing health risks. Global disease burdens are increasing due to factors like chronic conditions, cancer, and diabetes. Infectious diseases also remain a major cause of illness and death worldwide.
This document provides an outline of key topics in environmental health and toxicology, including:
1) Infectious diseases, antibiotic resistance, and toxicology are discussed as major factors impacting human health and disease burden globally.
2) Toxins like heavy metals, pesticides, and chemicals can have acute and chronic effects depending on dosage, and their movement and persistence in the environment vary.
3) Risk assessment of toxins involves measuring toxicity, understanding dose responses, and evaluating exposure levels to estimate health risks and set regulatory standards.
This document summarizes key concepts about risks, toxicology, and human health from Chapter 19 of G. Tyler Miller's Living in the Environment textbook. It discusses types of hazards people face, methods of assessing chemical and biological hazards, and estimating and managing risks. Risk is defined as the likelihood of harm from a hazard. Risk assessment involves identifying hazards, estimating risks, and comparing risks. The document also outlines approaches to risk analysis, management, and reduction.
This chapter discusses environmental health and toxicology. It introduces key concepts like what environmental health is, emerging infectious diseases, toxins and their effects on health, and how toxicity is measured. It also examines factors that influence the movement and concentration of toxins in ecosystems and organisms, and mechanisms that minimize toxic effects. Risk assessment and establishing public policy to address environmental health issues are also covered.
According to the document, in 2005 about 42 million people worldwide were infected with HIV/AIDS. There is no vaccine for HIV/AIDS and if contracted, it will eventually lead to death, though drugs can help some infected people live longer. AIDS has reduced life expectancy in sub-Saharan Africa significantly. Common risks to human health include biological, chemical, physical, and cultural hazards. Major infectious diseases disproportionately impact the poor in developing nations.
This document discusses several topics related to environmental health and toxicology, including infectious diseases, antibiotic and pesticide resistance, toxic chemicals, and policies around hazardous waste. It covers how toxins move through and impact the environment, human exposure and susceptibility, mechanisms for reducing toxicity, measuring toxicity through testing and risk assessment, and legislation like CERCLA and RCRA for hazardous waste disposal and superfund site cleanups.
Some chemicals can cause harm to human health. Toxic chemicals include carcinogens that cause cancer, mutagens that cause genetic mutations, and teratogens that cause birth defects. Many chemicals also affect the immune, nervous, and endocrine systems. The toxicity of a chemical depends on factors like dose, route of exposure, and individual susceptibility. Scientists use animal testing and epidemiological studies to estimate toxicity, but these have limitations. More research is needed to understand the health impacts of many chemicals, especially at low exposure levels. Efforts to reduce chemical pollution and require safety testing aim to apply the precautionary principle.
This document discusses environmental health and toxicology. It begins by defining environmental health and toxicology as focusing on external factors that cause disease, including elements of the natural and technological environments. It then discusses various diseases and their causes, the spread of infectious diseases, toxic chemicals and their effects, and mechanisms of toxicity and resistance. Throughout, it provides examples and details on specific diseases, chemicals, and concepts within environmental health and toxicology.
The document discusses several topics related to health and wellness. It provides information on skin anatomy and functions, processed foods consumption in the US, a study linking diet soda to obesity risk, risks of NSAIDs and congestive heart failure, how genes can be epigenetically influenced, quotes on the consequences of our actions, common symptoms associated with toxicity, diseases linked to toxicity, emotions and pH balance, sunscreen ingredients to avoid, leading causes of death in the US, and potential impacts of a super flu pandemic.
This document discusses the pervasive toxicity of modern life and provides recommendations for reducing toxic exposure and supporting the body's detoxification processes. It notes that chemicals are now present in many household and personal care products, food/beverages, and the built environment. Specific toxic substances discussed include heavy metals, pesticides, plastics, and electromagnetic fields. The document recommends avoiding these toxins, supporting detoxification with supplements like glutathione, using activated carbon, and addressing structural issues like heavy metal amalgam fillings and spinal misalignments that can impair detoxification. Overall it presents a model of toxicity as a primary driver of chronic disease and advocates lifestyle changes to reduce the toxic burden on the body.
Risk Analysis and Environmental Health HazardsChapter 4.docxSUBHI7
Risk Analysis and Environmental Health Hazards
Chapter 4
Pesticides and ChildrenMore harmful to children than adultsGreater exposurePlaying in contaminated fieldsPutting fingers/things in mouthGreater responseDeveloping bodies, more sensitiveRange of EffectsCancer, mental and/or physical disabilitiesIntelligenceMotor skills
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Pesticides and Children
*
Learning Objectives:
Define risk and risk assessment
Explain how risk assessment helps is manage potential health threats
A Perspective on Risks
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A Perspective on RisksRiskThe probability of harm (injury, disease, death, environmental damage) occurring under certain circumstancesInherent in our actions and our environmentWalking on stairs, using household appliances, driving/riding cars, flying, etc.Few of us think twice about it, even though it’s riskyIn order to manage risks, we need to have a sense of their causes, likelihoods, and effects
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A Perspective on Risks
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A Perspective on RisksRisk ManagementThe process of identifying, assessing, and reducing risks.Qualitative and quantitative methodEstimates the probability that an even will occur, so we can determine behavior/actions
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A Perspective on Risks
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A Perspective on RisksCurious dilemma:People accept big risks 1/3 of smokers die of diseases caused by smoking Average life expectancy is 8 yrs less for smokers)Get upset over very small risks1 in 1 million chance of getting cancer from pesticide residues on food)Perhaps due to perception of risks as things we can control smoking, diet, exercise, etc. vs. things we “can’t” controlPlane crashes, pesticides, nuclear waste
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A Perspective on Risks
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Global Climate Change
What are risk and risk assessment?
What are the four steps of risk assessment?
Environmental Health HazardsLearning Objectives:
Define toxicology and epidemiology
Explain why public water supplies are monitored for fecal coliform bacteria despite the fact that most strains of E. coli do not cause disease
Describe the link between environmental changes and emerging diseases, such as swine flu
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Environmental Health HazardsToxicantsChemicals with adverse effects on healthAll chemicals are toxic if exposure is high enoughToxicology studies the effects of toxicants on living organismsstudies the mechanisms that cause toxicitydevelops ways to prevent or minimize adverse effects
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Environmental Health HazardsEpidemiologyThe study of the effects of chemical (toxicants), biological (disease), and physical agents (accidents, radiation) on the health of human populationsStudies large groups of people and investigate range of causes and types of disease and injuries
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Environmental Health HazardsToxicityAcuteImmediate (short-term) effects after a single exposure; dizziness, nausea, deathChronicProlonged effects, to long-term exposure to toxicant
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Environmental Health HazardsDisease-Causing Agents in the EnvironmentPathogens: disease-causing org ...
Power point environmental and occupational healthLori Mungovan
Here are a few possible reasons why the government has not banned BPA more quickly:
1. Chemical companies that produce and use BPA in plastics manufacturing exert significant lobbying influence. Banning chemicals could hurt their profits.
2. The effects of low-dose exposure to endocrine disrupting chemicals like BPA are complex and long-term. It's difficult to definitively prove health impacts, which gives chemical companies arguments against regulation.
3. Government agencies tend to be more conservative in banning chemicals already in wide use. They prefer to see overwhelming scientific consensus first before taking drastic regulatory action.
4. Alternatives to BPA must be developed, tested and brought to market. Transitioning entire industries to new
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This document summarizes several articles from a public health newsletter. It discusses challenges related to childhood obesity like lack of access to healthy foods and physical activity in low-income communities. It also describes initiatives to address these issues, such as the New Jersey Partnership for Healthy Kids which works with local coalitions and has helped raise funds and awareness. Another article discusses the importance of breastfeeding for early childhood prevention of diseases.
The document discusses the dangers of modern toxins and provides a 3-step plan to detox safely from toxins. It outlines that toxins are ubiquitous in the environment and can make people overweight, weak, and susceptible to disease. It then details various sources of toxins like microwaves, household products, food, water and discusses their health effects. Finally, it proposes a 7-day food plan, lifestyle changes and supplements to eliminate toxins from the body through organs of elimination like the colon, kidneys, lungs and skin. It warns that detoxification may cause illness in some and to see a doctor immediately if feeling unwell.
This document provides an introduction to environmental health from Dr. Eman M. Mortada. It defines key terms, outlines learning objectives, and discusses the interdisciplinary nature of environmental health. Specifically, it explores the relationships between the environment, health, and disease. It examines how the environment can impact human health through various hazards like biological, chemical, and physical hazards. It also discusses how human activities impact the environment and provides some historical context of the field through figures like Hippocrates and John Snow.
The document discusses many common carcinogens (cancer-causing agents) that people worldwide are exposed to in their food, air, water, and consumer goods. It notes that cancer causes more deaths annually than AIDS, tuberculosis, and malaria combined. While awareness of carcinogens is growing, there is still an information gap between developed and developing nations regarding cancer prevention. Exposure to carcinogens is often beyond people's control, so the best defense is to educate oneself on limiting unnecessary exposure and making healthy choices.
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Environmental hazards & Human Health
1. Presented By:
Dr Mohd Akhter Ali
Assistant Professor
Department of Geography
Osmania University
Hyderabad telanagana
Phone: 7680989610
Email:drmohdakhterali@gmail.com
2.
3. A risk is the probability of suffering harm from
a hazard that can cause injury, disease, death,
economic loss, or damage.
◦ Probability—a mathematical statement about the
likelihood that harm will be suffered from a hazard.
“The lifetime probability of developing lung cancer from
smoking one pack of cigarettes per day is 1 in 250.” This
means that 1 of every 250 people who smoke a pack of
cigarettes every day will likely develop lung cancer over
a typical lifetime.
4. ◦ Risk assessment is the process of using statistical
methods to estimate how much harm a particular
hazard can cause to human health or to the
environment. It helps us to establish priorities for
avoiding or managing risks.
◦ Risk management involves deciding whether or how
to reduce a particular risk to a certain degree.
5.
6. Fig. 14-2, p. 349
Risk Assessment Risk Management
What is the hazard? How does it compare
with other risks?
Risk reduction
How much should it
be reduced?
Probability of risk
How likely is the
event?
Risk reduction strategy
How will the risk be
reduced?
Consequences of risk
What is the likely damage?
Financial commitment
How much money should
be spent?
Comparative risk analysis
Hazard identification
7. Biological hazards from more than 1,400
pathogens that can infect humans.
◦ A pathogen is an organism that can cause disease
in another organism.
◦ Bacteria.
◦ Viruses.
◦ Parasites.
◦ Protozoa.
◦ Fungi.
8. Chemical hazards from harmful chemicals
in air, water, soil, food, and human-made
products.
Natural hazards such as fire, earthquakes,
volcanic eruptions, floods, and storms.
Cultural hazards such as unsafe working
conditions, unsafe highways, criminal
assault, and poverty.
Lifestyle choices such as smoking, making
poor food choices, drinking too much
alcohol, and having unsafe sex.
9.
10. An infectious disease is caused when a
pathogen such as a bacterium, virus, or
parasite invades the body and multiplies in its
cells and tissues.
◦ Tuberculosis, flu, malaria, and measles.
Bacteria are singe-cell organisms that are
found everywhere. Most are harmless or
beneficial. A bacterial disease results from an
infection as the bacteria multiply and spread
throughout the body.
11. Viruses are smaller than bacteria and work by
invading a cell and taking over its genetic
machinery to copy themselves. They then
multiply and spread throughout one’s body,
causing a viral disease such as flu or AIDS
A transmissible disease is an infectious
bacterial or viral disease that can be
transmitted from one person to another.
12. A nontransmissible disease is caused by
something other than a living organism and
does not spread from one person to another.
◦ Examples include cardiovascular (heart and blood
vessel) diseases, most cancers, asthma, and diabetes.
In 1900, infectious disease was the leading
cause of death in the world.
Greatly reduced by a combination of better
health care, the use of antibiotics to treat
infectious diseases caused by bacteria, and the
development of vaccines.
13.
14. Humans
Fetus and babies
Other humans
Water Air
Insects
Wild animals
Livestock
Pets Food
Stepped Art
Fig. 14-3, p. 351
15. Infectious diseases remain as serious health threats,
especially in less-developed countries.
Spread through air, water, food, and body fluids.
A large-scale outbreak of an infectious disease in an
area is called an epidemic.
A global epidemic such as tuberculosis or AIDS is called
a pandemic.
Many disease-carrying bacteria have developed genetic
immunity to widely used antibiotics and many disease-
transmitting species of insects such as mosquitoes have
become immune to widely used pesticides that once
helped to control their populations.
16.
17. Disease
(type of agent) Deaths per year
Pneumonia and flu
(bacteria and viruses)
3.2 million
HIV/AIDS (virus) 1.8 million
Diarrheal diseases
(bacteria and viruses)
1.6 million
Tuberculosis
(bacteria)
1.3 million
Measles
(virus)
800,000
Malaria
(protozoa)
780,000
Hepatitis B
(virus)
600,000 Stepped Art
Fig. 14-4, p. 351
18.
19.
20. A toxic chemical is one that can cause temporary or
permanent harm or death to humans and animals.
In 2004, the EPA listed arsenic, lead, mercury, vinyl
chloride (used to make PVC plastics), and
polychlorinated biphenyls (PCBs) as the top five toxic
substances in terms of human and environmental
health.
There are three major types of potentially toxic agents.
◦ Carcinogens are chemicals, types of radiation, or certain
viruses that can cause or promote cancer.
◦ Mutagens are chemicals or forms of radiation that cause
mutations, or changes, in the DNA molecules found in cells, or
that increase the frequency of such changes.
◦ Teratogens are chemicals that cause harm or birth defects to a
fetus or embryo.
21. Our body’s immune system protects us
against disease and harmful substances by
forming antibodies that render invading
agents harmless, but some chemicals
interfere with this process.
◦ Arsenic.
◦ Methylmercury.
◦ Dioxins.
22. Some natural and synthetic chemicals in the
environment, called neurotoxins, can harm
the human nervous system, causing the
following effects.
◦ Behavioral changes.
◦ Learning disabilities.
◦ Retardation.
◦ Attention deficit disorder.
◦ Paralysis.
◦ Death.
23. Examples of neurotoxins.
◦ PCBs.
◦ Methylmercury.
◦ Arsenic.
◦ Lead.
◦ Certain pesticides.
24. The EPA estimates that about 1 in 12 women of
childbearing age in the US has enough mercury in her
blood to harm a developing fetus.
◦ The greatest risk from exposure to low levels of methylmercury
is brain damage in fetuses and young children.
◦ Methylmercury may also harm the heart, kidneys, and immune
system of adults.
◦ EPA advised nursing mothers, pregnant women, and women who
may become pregnant not to eat shark, swordfish, king
mackerel, or tilefish and to limit their consumption of albacore
tuna.
◦ In 2003, the UN Environment Programme recommended phasing
out coal-burning power plants and waste incinerators
throughout the world as rapidly as possible.
◦ Other recommendations are to reduce or eliminate mercury in
the production of batteries, paints, and chlorine by no later than
2020.
25.
26. The endocrine system is a complex network of
glands that release tiny amounts of hormones
that regulate human:
◦ Reproduction.
◦ Growth.
◦ Development.
◦ Learning ability.
◦ Behavior.
27. Hormonally active agents (HAA) are
synthetic chemicals that disrupt the
endocrine system in humans and some
other animals.
◦ Examples include aluminum, Atrazine™ and several
other herbicides, DDT, PCBs, mercury , phthalates,
and bisphenol A (BPA).
◦ Some disrupt the endocrine system by attaching to
estrogen receptor molecules.
◦ Thyroid disrupters cause growth, weight, brain, and
behavioral disorders.
28. ◦ BPA is found in plastic water bottles, baby bottles and
the plastic resins line food containers.
Studies found that low levels of BPA cause numerous
problems such as brain damage, early puberty, prostate
cancer, breast cancer, and heart disease.
Studies funded by the chemical industry found no evidence
or only weak evidence, for adverse effects from low-level
exposure to BPA in test animals.
In 2008, the FDA concluded that BPA in food and drink
containers does not pose a health hazard.
In 2010, Canada classified BPA as a toxic chemical and
banned its use in baby bottles, and the EU voted to ban the
sale of plastic baby bottles that contain BPA.
29. ◦ Phthalates are found in detergents, perfumes,
cosmetics, deodorants, soaps, and shampoo, and in
PVC products such as toys, teething rings, and
medical tubing used in hospitals.
Phthalates cause cancer and other health problems in
laboratory animals.
30.
31. Toxicology is the study of the harmful effects
of chemicals on humans and other organisms.
◦ Toxicity is a measure of the harmfulness of a
substance.
◦ Any synthetic or natural chemical can be harmful if
ingested in a large enough quantity.
◦ The dose is the amount of a harmful chemical that a
person has ingested, inhaled, or absorbed through
the skin.
◦ Many variables can affect the level of harm caused by
a chemical.
Toxic chemicals usually have a greater effect on fetuses,
infants, and children than on adults.
32. The most widely used method for determining
toxicity is to expose a population of live
laboratory animals to measured doses of a
specific substance under controlled conditions.
Lab mice and rats are widely used because
their systems function somewhat like human
systems.
◦ Results plotted in a dose-response curve.
◦ Determine the lethal dose.
◦ Median lethal dose (LD50) is the dose that can kill 50%
of the animals (usually rats and mice) in a test
population within an 18-day period.
33.
34.
35.
36.
37.
38. The best ways to reduce one’s risk of
premature death and serious health
problems are to:
◦ avoid smoking and exposure to smoke
◦ lose excess weight
◦ reduce consumption of foods containing
cholesterol and saturated fats
◦ eat a variety of fruits and vegetables
◦ exercise regularly
◦ drink little or no alcohol
◦ avoid excess sunlight
◦ practice safe sex
39.
40.
41. Many people deny or shrug off the high-risk
chances of death (or injury) from voluntary
activities they enjoy, such as:
◦ Motorcycling (1 death in 50 participants).
◦ Smoking (1 in 250 by age 70 for a pack-a-day
smoker)
◦ Hang gliding (1 in 1,250).
◦ Driving (1 in 3,300 without a seatbelt and 1 in
6,070 with a seatbelt).
42. Some of these same people may be terrified
about their chances of being killed by:
◦ A gun (1 in 28,000 in the United States).
◦ Flu (1 in 130,000).
◦ Nuclear power plant accident (1 in 200,000).
◦ West Nile virus (1 in 1 million).
◦ Lightning (1 in 3 million).
◦ Commercial airplane crash (1 in 9 million).
◦ Snakebite (1 in 36 million).
◦ Shark attack (1 in 281 million).
43. Five factors can cause people to be being
more or less risky than experts judge.
◦ Fear.
◦ Degree of control we have.
◦ Whether a risk is catastrophic instead of chronic.
◦ Some people suffer from optimism bias, the
belief that risks that apply to other people do not
apply to them.
◦ Many risky things are highly pleasurable and give
instant gratification.
44. Compare risks.
Determine how much risk you are willing to
accept.
Evaluate the actual risk involved.
Concentrate on evaluating and carefully
making important lifestyle choices.
45. We face significant hazards from infectious
diseases such as flu, AIDS, diarrheal diseases,
malaria, and tuberculosis, and from exposure to
chemicals that can cause cancers and birth defects,
and disrupt the human immune, nervous, and
endocrine systems.
Because of the difficulty in evaluating the harm
caused by exposure to chemicals, many health
scientists call for much greater emphasis on
pollution prevention.
Becoming informed, thinking critically about risks,
and making careful choices can reduce the major
risks we face.
46. The slides that follow are those taken out of
the “long version” of this same lecture. You
should still read the following slides for
better understanding, but I will not go over
them in class unless you have specific
questions.
47. Viruses evolve quickly, are not affected by
antibiotics, and can kill large numbers of
people.
◦ The biggest killer is the influenza, or flu, virus,
which is transmitted by the body fluids or airborne
emissions of an infected person.
◦ The second biggest viral killer is the human
immunodeficiency virus (HIV).
HIV infects about 1.8 million people each year, and the
complications resulting from AIDS kill about 1.8
million people annually.
48. ◦ The third largest viral killer is the hepatitis B
virus (HBV), which damages the liver and kills
about a million people each year.
Transmitted by unsafe sex, sharing of needles by
drug users, infected mothers who pass the virus to
their offspring before or during birth, and exposure
to infected blood.
◦ Emergent diseases are illnesses that were
previously unknown or were absent in human
populations for at least 20 years.
One is the West Nile virus, which is transmitted to
humans by the bite of a common mosquito that is
infected when it feeds on birds that carry the virus.
49. ◦ Greatly reduce your chances of getting infectious
diseases by practicing good, old-fashioned
hygiene.
Wash your hands thoroughly and frequently.
Avoid touching your face.
Stay away from people who have flu or other viral
diseases.
50. The percentage of global death rate from infectious
diseases decreased from 35% to 17% between 1970 and
2006, and is projected to drop to 16% by 2015.
From 1971-2006, immunizations of children in
developing countries to prevent tetanus, measles,
diphtheria, typhoid fever, and polio increased from 10%
to 90%—saving about 10 million lives each year.
An important breakthrough has been the development
of simple oral rehydration therapy— administering a
simple solution of boiled water, salt, and sugar or rice.
Philanthropists have donated billions of dollars toward
improving global health, with special emphasis on
infectious diseases in less-developed countries.
51.
52.
53. Fig. 14-9, p. 357
Atmosphere
Crops
Vegetation
Surface water Humans
Animals
Vegetation
54. Toxicity also depends on genetic makeup, which
determines an individual’s sensitivity to a particular toxin.
Some individuals are sensitive to a number of toxins—a
condition known as multiple chemical sensitivity (MCS).
How well the body’s detoxification systems (such as the
liver, lungs, and kidneys) work.
Solubility: water-soluble toxins and oil- or fat-soluble
toxins.
Persistence, or resistance to breakdown such as DDT and
PCBs.
Biological magnification, in which the concentrations of
some potential toxins in the environment increase as they
pass through the successive trophic levels of food chains
and webs.
55. The damage to health resulting from
exposure to a chemical is called the
response.
◦ Acute effect is an immediate or rapid harmful
reaction ranging from dizziness and nausea to
death.
◦ Chronic effect is a permanent or long-lasting
consequence (kidney or liver damage, for example)
of exposure to a single dose or to repeated lower
doses of a harmful substance.
56. Case reports provide information about people
suffering some adverse health effect or death
after exposure to a chemical.
Epidemiological studies, which compare the
health of people exposed to a particular
chemical (the experimental group) with the
health of a similar group of people not exposed
to the agent (the control group), but limited by:
◦ Too few people have been exposed to high enough
levels of a toxic agent to detect statistically significant
differences.
57. ◦ Usually takes a long time.
◦ Closely linking an observed effect with exposure
to a particular chemical is difficult because
people are exposed to many different toxic
agents throughout their lives and can vary in their
sensitivity to such chemicals.
◦ Cannot evaluate hazards from new technologies
or chemicals to which people have not yet been
exposed.
58. Almost everyone is now exposed to potentially
harmful chemicals that have built up to trace levels
in their blood and in other parts of their bodies.
In most cases, we do not know if we should be
concerned about trace amounts of various
synthetic chemicals because there is too little data
and because of the difficulty of determining the
effects of exposures to low levels of these
chemicals.
Possible potential long-term effects on the human
immune, nervous, and endocrine systems.
The risks from trace levels may be minor.
59. All methods for estimating toxicity levels and risks
have serious limitations.
Only 10% of the 80,000+ registered synthetic
chemicals in commercial use have been thoroughly
screened for toxicity, and only 2% have been
adequately tested to determine whether they are
carcinogens, mutagens, or teratogens.
Because of insufficient data and the high costs of
regulation, federal and state governments do not
supervise the use of nearly 99.5% of the
commercially available chemicals in the US.
60. Some are pushing for much greater emphasis
on pollution prevention.
Do not release into the environment
chemicals that we know or suspect can cause
significant harm.
◦ Look for harmless or less harmful substitutes for
toxic and hazardous chemicals.
◦ Recycle them within production processes to keep
them from reaching the environment.
61. The precautionary principle advocates when there
is reasonable but incomplete scientific evidence
of significant or irreversible harm to humans or
the environment from a proposed or existing
chemical or technology, we should take action to
prevent or reduce the risk instead of waiting for
more conclusive scientific evidence.
◦ New chemicals/technologies would be assumed to be
harmful until scientific studies could show otherwise.
◦ Existing chemicals/technologies that appear to have a
strong chance of causing significant harm would be
removed from the market until their safety could be
established.
62. In 2000, a global treaty banned or phased out the use
of 12 of the most notorious persistent organic
pollutants (POPs), also called the dirty dozen. The list
includes DDT and eight other pesticides, PCBs, and
dioxins.
In 2007, the European Union enacted regulations known
as REACH (for registration, evaluation, and
authorization of chemicals) that put more of the burden
on industry to show that chemicals are safe.
◦ REACH requires the registration of 30,000 untested,
unregulated, and potentially harmful chemicals.
◦ The most hazardous substances are not approved for use if
safer alternatives exist.
◦ When there is no alternative, producers must present a
research plan aimed at finding one
63. Risk analysis involves identifying hazards and
evaluating their associated risks.
◦ Risk assessment.
◦ Ranking risks (comparative risk analysis).
◦ Determining options and making decisions about
reducing or eliminating risks (risk management).
◦ Informing decision makers and the public about
risks (risk communication).
64. The greatest risk by far is poverty.
◦ The high death toll ultimately resulting from
poverty is caused by malnutrition, increased
susceptibility to normally nonfatal infectious
diseases, and often-fatal infectious diseases
transmitted by unsafe drinking water.
The second greatest risk is gender.
65. The more complex a technological system, and
the more people needed to design and run it,
the more difficult it is to estimate the risks of
using the system.
The overall reliability or the probability that a
person, device, or complex technological system
will complete a task without failing is the
product of:
◦ Technology reliability.
◦ Human reliability.