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Chapter 11 Chemicals and Our World

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Chapter 11 Chemicals and Our World, Copyright HRW 2005, posted for classroom use under the fair use guidelines of reprinting 1 chapter in a book for classroom use only.

Chapter 11 Chemicals and Our World, Copyright HRW 2005, posted for classroom use under the fair use guidelines of reprinting 1 chapter in a book for classroom use only.

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    Chapter 11 Chemicals and Our World Chapter 11 Chemicals and Our World Document Transcript

    • Natural and Synthetic 1 Chemicals Imagine that you are hiking with your friend. You stop by a READI NG WARM-U P stream and take a sip of the water. “Water tastes so much better without any chemicals in it!” exclaims your friend.Objectives Explain the difference between Is the water from the stream truly free of chemicals? No! In• natural and synthetic chemicals. fact, water itself is a chemical. A chemical is any substance• Give examples of natural and that has a defined composition. The stream’s water probably synthetic chemicals. contains other chemicals, such as dissolved minerals and gases,Terms to Learn too. You are surrounded by chemicals everywhere you go. Evenchemical your body is made of chemicals! All chemicals can be divided into two groups: natural chemicals and synthetic chemicals. READI NG STRATEGYDiscussion Read this section silently. Natural ChemicalsWrite down questions that you have Natural chemicals are chemicals that can be found in natureabout this section. Discuss your ques- or that are made by natural processes. The water, rocks, andtions in a small group. plants in Figure 1 are natural chemicals or are made of natu- ral chemicals. Other examples of natural chemicals are some metals, gases in the air, and proteins. You may think that allchemical any substance that has a natural chemicals are safe. However, some natural chemicals,defined composition such as the poison in poison ivy, can be dangerous.Figure 1 Everything you see inthis photo is made of naturalchemicals.324 Chapter 11 Chemicals and Our World Copyright © by Holt, Rinehart and Winston. All rights reserved.
    • Figure 2 Natural Chemicals in an Orange An orange is made of many natural chemicals, including water, fructose, and citric acid. Citric acid, C6H8O7, gives oranges their tart taste. Fructose, C6H12O6, is a sugar that is commonly found in fruits. Water, H2O, makes up a large part of all plants and animals.Structure of Natural ChemicalsParticles of natural chemicals have a wide range of sizes. Forexample, a particle of helium gas is only one atom. But particlesof proteins, such as the proteins that make up some foods, aremade of hundreds or thousands of atoms joined together bychemical bonds. Some things, such as plants and animals, aremade up of many kinds of natural chemicals. Figure 2 showsthree of the many natural chemicals that make up an orange.Notice that the structure of natural chemicals can be simple,like the structure of water, or complex, like the structure ofcitric acid.Production of Natural ChemicalsIt might be tempting to say that natural chemicals are chemicals Natural Dyes Native Ameri-that are not made by humans. But that statement is not true! cans used natural dyes to colorThe human body makes natural chemicals through natural their clothing and artwork.processes all of the time. When you breathe, you release the Found in plants, these dyes arenatural chemical carbon dioxide. Your body also makes chemi- natural chemicals that can be removed from the plants bycals that are more complex, such as proteins and fats. boiling or soaking plant parts Natural chemicals are also made by other living things, in water. Native Americanssuch as plants, insects, and bacteria. For example, green plants used the bark, leaves, petals,can make chemicals called carbohydrates through the process and berries of various plantsof photosynthesis (FOHT oh SIN thuh sis). But some natural to produce different colors. Learn how to extract dyes fromchemicals are made through natural processes that don’t plants and color a cotton raginvolve living things. Minerals and some gems form through or T-shirt by using a naturalprocesses involving the Earth. dye that you made.Reading Check Name three kinds of natural chemicals thatyour body makes. (See the Appendix for answers to Reading Checks.) Section 1 Natural and Synthetic Chemicals 325Copyright © by Holt, Rinehart and Winston. All rights reserved.
    • Synthetic Chemicals The word synthetic usually refers to something that is made by humans or to something that is not natural. So, a synthetic chemical is a chemical that is not found in nature and that is not made by natural processes. Synthetic chemicals are very common in today’s modern world. You probably use things made of synthetic chemicals every day. Reading Check What is a synthetic chemical? Kinds of Synthetic Chemicals Take a look around you. Do you see things made from plas- tic? Perhaps you see a plastic bottle or the plastic housing of a computer monitor. Plastics are common synthetic chemi- cals. Different kinds of plastics have different properties. For example, some plastics are flexible, some are rigid, some are clear, and some are colored. Their different properties allow plastics to be used to make various things. Many medicines are also examples of synthetic chemicals. The pain reliever that you might take when you have a head- ache and the allergy medicines that keep you from sneezing are synthetic chemicals. You can also find synthetic chemicals in the food you eat and the clothes you wear. Although food is mostly made up of natural chemicals, synthetic chemicals are added to some foods. Examples of synthetic food additives are artificial sweet-Figure 3 The white rope beingpulled out of the liquid is nylon. eners and food coloring. Similarly, many clothes are made fromNylon forms at the surface natural chemicals. But some clothing fabrics are partially orbetween the two chemicals in the completely made of synthetic fibers. Polyester is a syntheticbeaker. Nylon is one of the most fiber, as is nylon, shown in Figure 3.widely used synthetic chemicals. Nylon backpack Nylon string Nylon jacket326 Chapter 11 Chemicals and Our World Copyright © by Holt, Rinehart and Winston. All rights reserved.
    • Production of Synthetic ChemicalsSynthetic chemicals are made during chemical reactionsbetween natural chemicals, other synthetic chemicals, or both.Scientists develop ways to make synthetic chemicals throughlaboratory experiments. Often, scientists try to make chemicalsthat have specific properties or a specific combination andarrangement of atoms. For example, a scientist may try tomake a strong, rigid plastic like that used in the helmet shownin Figure 4. Another scientist may try to make a medicine totreat a certain disease. Sometimes, scientists produce useful synthetic chemicalsby accident. For example, the synthetic chemical Teflon™ wasfirst made by mistake. Now, Teflon is used to make nonstickcookware and to make fabrics stain resistant. Silly Putty™ isanother example of a synthetic chemical that was made byaccident. Silly Putty was first made when a scientist was try- Figure 4 This skateboarder’s helmet is made from variousing to make a synthetic rubber. The putty did not have the synthetic chemicals. Both theproperties of rubber but did have properties that made the rigid plastic cover and theputty a fun toy! cushioning foam will protect the skateboarder if he falls. Using Key Terms Critical Thinking Review 1. Use the following term in a 6. Applying Concepts The chemi- sentence: chemical. cal sodium chloride (table salt) can be found in seawater and Understanding Key Ideas can also be made by scientists in a laboratory. Is sodium chloride Summary 2. Which of the following is a synthetic chemical? a natural or a synthetic chemi- cal? Explain your answer. a. water c. nylon • Chemicals are sub- stances that have b. fructose d. oxygen 7. Expressing Opinions How do synthetic chemicals affect your defined compositions. 3. What is the difference between quality of life? Explain your • Natural chemicals are natural chemicals and synthetic answer with specific examples. found in nature or chemicals? are made by natural processes. 4. List four examples of natural chemicals and four examples • Synthetic chemicals of synthetic chemicals. are substances that are not formed by natural Developed and maintained by the processes and that are Math Skills National Science Teachers Association made by humans. 5. Aspartame is a synthetic chemi- For a variety of links related to this cal that is used as an artificial chapter, go to www.scilinks.org sweetener in many low-Calorie foods. Aspartame’s chemical Topic: Chemicals formula is C14H18N2O5. What SciLinks code: HSM0277 percentage of the atoms in aspartame are oxygen, O? 327Copyright © by Holt, Rinehart and Winston. All rights reserved.
    • Chemical Benefits 2 Achoo! It’s the morning of a big math test. You studied hard and are ready for the test, but you woke up feeling terrible. Your nose is running and you can’t stop sneezing. You don’t READI NG WARM-U P want to miss the test, but what can you do to feel better?Objectives Perhaps your runny nose and sneezing are the result of a cold• Explain the beneficial effects of or allergies. In either case, you could take some medicine to different kinds of medicines. relieve your symptoms. Medicines are just one example of the• Describe how food preservatives products in which chemicals are used to help people. Read on work and why they are useful. to learn about medicines and other benefits of chemicals.• Describe two ways that chemicals help improve crop yield.• Explain the role of chemicals in Medicines sanitation. A medicine is a substance that is used to cure, prevent, orTerms to Learn treat illness or discomfort. Medicines may be made of onemedicine chemical or a mixture of chemicals. All medicines improvepotency a person’s health or well-being by causing a change in thedose person’s physical or psychological state. Table 1 lists several kinds of medicines and their effects. READI NG STRATEGY Some medicines are natural chemicals, but many medicines are synthetic chemicals. An example of a natural medicine isReading Organizer As you read thissection, create an outline of the section. penicillin. Penicillin kills certain kinds of bacteria and is pro-Use the headings from the section in duced by a type of mold. An example of a synthetic medicineyour outline. is the pain reliever aspirin. Aspirin is made by changing a naturally occurring acid through a chemical reaction.medicine any drug that is usedto cure, prevent, or treat illness or Table 1 Kinds of Medicinesdiscomfort Kind Example Effect Analgesic acetaminophen It relieves pain. Antihistamine diphenhydramine It helps relieve minor allergy symptoms. Antacid aluminum hydroxide It neutralizes stomach acid for relief from heartburn. Antibiotic penicillin It kills some kinds of bacteria to help cure infections. Hormone insulin Different hormones work differently; insulin helps treat diabetes. Vaccine chickenpox vaccine It helps prevent infections in people exposed to the disease.328 Chapter 11 Chemicals and Our World Copyright © by Holt, Rinehart and Winston. All rights reserved.
    • Figure 1 A dose of this children’s medicine depends on the weight of the child taking it. Directions dose may be repeated every 4-6 hours do not exceed 4 doses in a 24-hr period AGE WEIGHT DOSE children 6 to11 48-49 lbs 2 teaspoonfuls years children under 6 under 48 lbs ask a doctor yearsMedicines, Potency, and Side EffectsTo be a good medicine, a medicine must be potent. The potency potency the power of a medicineof a medicine is the power of a medicine to produce its desired to produce a desired effecteffect. For example, penicillin is potent at killing certain kinds dose the quantity of medicine thatof bacteria. Good medicines also have to be safe. Penicillin needs to be taken over a period ofwouldn’t be very useful if it damaged the heart while it was timekilling bacteria. But penicillin doesn’t damage the heart. So,for most people, penicillin is safe. However, no medicine is perfectly safe for everyone. Mostmedicines cause effects that differ from the intended effect.These effects are called side effects. Good medicines have minorside effects, such as headaches or sleepiness. If a medicinehas too many side effects or if the side effects are severe, themedicine may not be safe for everyone to use. Reading Medicine LabelsReading Check What is potency? (See the Appendix for answers to Ask a parent to help youReading Checks.) gather four or five medicines. Read the labels of the medi-Taking Medicines Properly cines. In your science jour- nal, make a chart that showsWhen you take a medicine, it is important to take the correct the medicine names, thedose of the medicine. A dose is the amount of medicine that uses of each medicine, theneeds to be taken at one time. The amount of medicine that proper dose for each medi-needs to be taken often depends on who is taking the medi- cine, and the side effects of each medicine. Ask your par-cine. For example, children take a smaller dose of a medicine ent if he or she experiencedthan adults take. Also, small children take smaller doses than any of the side effects, andlarger children take, as shown in Figure 1. Different doses are make a note of his or hernecessary because people are of different sizes. Adults are larger answers in the chart.than children, so adults need a larger dose of medicine to havethe correct concentration of medicine in their bodies. Section 2 Chemical Benefits 329Copyright © by Holt, Rinehart and Winston. All rights reserved.
    • Food Preservatives Chemicals are also beneficial when they are used as food pre- servatives. A food preservative is a chemical that can prevent or slow down the spoiling of food. Food preservatives are useful because they keep food fresh during the time it takes to trans- Apple Brown Betty port the food to stores. They also allow you to store foods for 1. Use a knife to cut four longer periods of time and keep foods safe to eat. bite-sized pieces from an apple. Place a toothpick in each piece. How Preservatives Work 2. Dip one piece of apple Food preservatives work in different ways. Some food preser- in water, one in vegetable vatives prevent the growth of bacteria or mold. For example, oil, and one in lemon antibiotics can be added to poultry, fish, or canned goods to juice. Coat all sides of kill bacteria. And sorbic acid can be added to fruit juice or each piece. Do not dip the fourth piece in anything. dried fruit to prevent the growth of mold. If certain bacteria Place the pieces on a and molds are eaten, they can make people sick. So, food paper towel. preservatives can keep you healthy. 3. Record your observations Other food preservatives work by preventing chemical of the pieces. Then, predict reactions that break down foods. For example, preservatives what will happen to the called BHA and BHT are added to foods such as margarine pieces. After 15 minutes, observe the apple pieces and cereals to prevent the foods from becoming rancid. When again and record your food becomes rancid, it smells and tastes bad. The chemical observations. How did the vitamin C can be added to fruits to prevent a chemical reaction pieces change? that causes the fruits to turn brown. Rancid or browned foods 4. Suppose that you are mak- may not make you sick, but you may not want to eat them. ing a fruit salad that has Still other preservatives prevent foods from going stale. pieces of apple in it. What could you do to keep the These preservatives are found in store-bought cookies. They pieces of apple looking are not used in homemade cookies, such as the ones shown appetizing? in Figure 2, so eat your cookies soon after you bake them!Figure 2 Although homemadecookies are fun to make, they donot contain preservatives and willnot stay fresh as long as store-bought cookies will.330 Chapter 11 Copyright © by Holt, Rinehart and Winston. All rights reserved.
    • Crop YieldA third way in which chemicals are beneficial isin their use to improve crop yields in farming.Farmers use different chemicals to increase theamounts of fruits or vegetables that are grown ona given amount of land. Two groups of chemicalsused by farmers are fertilizers and pesticides.FertilizersAll plants, including fruit trees and vegetable plants,need certain elements to grow well. The mostimportant elements for plant growth are nitrogen,phosphorus, and potassium. These elements can befound in soil, but the soil where crops are grownsometimes does not have enough of these elements.To overcome this problem, farmers put fertilizers intheir fields. A fertilizer is a chemical that improvesthe quality of the soil to produce plants. Most fertilizers are a mixture of chemicals thatcontain nitrogen, phosphorus, and potassium.Fertilizers help farmers grow large, healthy plantsthat produce large amounts of fruits and vegetables.Without fertilizers, world food production would Figure 3 No one wants to eatbe less than half of what it is today. an ear of corn with an insect in it! Therefore, pesticides are Reading Check What three elements are most sprayed on corn fields to killimportant for plant growth? insects and other pests before they get into the corn.PesticidesWhen growing fruits and vegetables for people to eat, farmersoften discover that other things like to eat the food, too! InNorth America, insects, such as the one shown in Figure 3, eatabout 13% of all crops. Worldwide, pests destroy about 33%of the world’s potential food harvest. Insects are just one of several kinds of organisms that areconsidered pests. A pest is any organism that lives where it isnot wanted or grows in large enough numbers to cause eco-nomic damage. Pests include certain rodents, fungi, bacteria,and plants. Plant pests are often called weeds. To reduce the loss of crops to pests, farmers often use pesti-cides. A pesticide is a poison that is used to kill insects, weeds,and other crop pests. During the last 50 years, scientists haveinvented many new pesticides. The pesticides are very effective,and farmers can rely on these pesticides to almost completelyprotect their crops from pests. However, farmers must be carefulnot to use large amounts of pesticides because pesticides canbe dangerous to human health and the environment. Section 2 Chemical Benefits 331Copyright © by Holt, Rinehart and Winston. All rights reserved.
    • Sanitation Chemicals are also beneficial in sanitation. Sanitation is the practice of providing sewage and solid waste disposal, clean drinking water, and clean living conditions. Good sanitation helps prevent the spread of diseases and infections. Chemicals and Large-Scale Sanitation Some parts of good sanitation depend on the use of chemicals. For example, the chemical chlorine is used in the treatment of sewage wastewater. Wastewater is treated because it must be cleaned before it can be returned to a natural body of water. If the wastewater is not cleaned, the environment could be damaged by pollution. Chlorine helps clean wastewater by killing harmful bacteria and other microorganisms. Chlorine and other chemicals are also used in the treat- ment of water for household use. Figure 4 shows how water is treated to become safe drinking water. Reading Check How does chlorine help clean wastewater? Figure 4 Drinking-Water Treatment First Filtration The source water 1 supply is filtered to remove large organisms and trash. 3 Second Filtration Layers of sand, gravel, and hard coal filter the remaining impurities. Coagulation Alum is mixed in and 2 forms sticky globs. Bacteria cling to the globs, which settle out. Chlorination Additional Treatment Fluoride may be added to 4 Chlorine is added 6 prevent tooth decay. Sodium compounds or lime may also be added to soften hard water. Treated to prevent bacteria from growing in the water. water is then ready for household use. Aeration Air is forced through the 5 water to release unwanted gases, which reduces odor and improves taste.332 Chapter 11 Chemicals and Our World Copyright © by Holt, Rinehart and Winston. All rights reserved.
    • Chemicals and Household SanitationSanitation is also important in your home. Chemicals inhousehold cleaners are needed to kill bacteria and otherdisease-causing microorganisms. For example, some kitchenand bathroom surface cleaners contain bleach. Bleach is acommon name for the chemical sodium hypochlorite and iseffective at killing bacteria and viruses. Another useful chemicalis hydrogen peroxide. As shown in Figure 5, hydrogen peroxidecan be applied to wounds to prevent infections. Figure 5 After a wound is washed with soap and water, using hydrogen peroxide on the wound can help prevent an infection. Using Key Terms Math Skills Review 1. Use each of the following terms 9. One spring, a farmer plants in a separate sentence: medicine, 70 acres of soybeans. Every year, potency, and dose. she loses approximately 20% of her crop to pests. How many Understanding Key Ideas acres of soybeans can she expect Summary 2. Which of the following kinds to harvest? Suppose the farmer tries a new pesticide and reduces of medicines should you take if her crop loss to 10%. How many Medicines are sub- • stances that are used to you have a headache? acres will she harvest? cure, prevent, or treat a. hormone c. analgesic illness or discomfort. b. vaccine d. antacid Critical Thinking Good medicines are 3. Pesticides can be used to kill 10. Making Inferences Why is it potent and safe. a. insects. important to read the directions • chemicals that can are Food preservatives slow b. weeds. every time you take a medicine? down or prevent the c. bacteria. 11. Applying Concepts Suppose spoiling of food. d. All of the above that you buy a loaf of bread and bake a loaf of bread on the same • and pesticidesfertilizers Chemicals in help 4. Describe the effects of antihista- mines, antibiotics, and vaccines. day. You store both loaves on the kitchen counter. Which loaf increase crop yields. 5. Why do children need smaller should you eat first? Explain. • Chemicals are used in doses of medicine than adults sanitation to kill harm- need? ful bacteria and other microorganisms. 6. How do food preservatives work? What are two benefits of using food preservatives? 7. Describe two ways that chemi- For a variety of links related to this cals can be used to improve crop chapter, go to www.scilinks.org yields. Topic: Medicines from Plants; Food Preservation 8. Why are chemicals important in SciLinks code: HSM0934; HSM0597 sanitation? 333Copyright © by Holt, Rinehart and Winston. All rights reserved.
    • Chemical Risks 3 Imagine that you and a friend are building a model airplane for a school project. As you pick up the tube of glue, your friend says, “Be careful—that’s a dangerous chemical.” READI NG WARM-U P Why is glue dangerous? One reason is that you can becomeObjectives dizzy if you inhale too many fumes from glue. But that doesn’t• List three ways that you can be mean that you shouldn’t use glue. It just means that you have exposed to dangerous chemicals. to use glue in a safe way.• Identify chemicals that may contribute to certain human health conditions. Dangerous Chemicals and Exposure• Describe possible means to eliminate Although many chemicals are safe, some chemicals can be or reduce the effects of dangerous dangerous to your health. Even useful chemicals, such as chemicals. model-airplane glue, can be dangerous. Usually, health prob-Terms to Learn lems resulting from dangerous chemicals depend on a person’scarcinogen exposure to the chemicals. Exposure to a chemical means being in contact with the chemical. Greater exposure leads to greater READI NG STRATEGY risk of developing problems. You can be exposed to dangerous chemicals in many ways.Paired Summarizing Read this sectionsilently. In pairs, take turns summariz- You can eat or drink dangerous chemicals. Alcohol and pesti-ing the material. Stop to discuss ideas cides on fruits and vegetables are examples of chemicals thatthat seem confusing. are eaten. You can touch dangerous chemicals. Some chemi- cals, such as mercury, can be absorbed through your skin if you touch them. And you can inhale dangerous chemicals, such as the fumes from model-airplane glue. The chemicals in cigarette smoke, shown in Figure 1, are also examples of dangerous chemicals that can be inhaled. Health problems resulting from chemicals can also be due to a person’s individual susceptibility. Individual susceptibility is a person’s risk of being affected negatively by something dangerous. When exposed to a danger, some people are at greater risk than other people are. For example, penicillin is safe for many people, but some people are severely allergic to penicillin. For people who are highly allergic to penicillin, penicillin can be deadly. Figure 1 Cigarette smoke contains many dangerous chemicals. Limit your exposure by choosing not to smoke and avoiding secondhand smoke.334 Chapter 11 Chemicals and Our World Copyright © by Holt, Rinehart and Winston. All rights reserved.
    • Diseases and Chemical ExposureSome diseases can be caused by exposure to certain chemicals.Therefore, knowing what chemicals can be dangerous will helpyou reduce your risk of getting certain diseases. Read on to Evaluating Statisticslearn about some diseases that can be caused by chemical The American Cancer Societyexposure. estimated that 699,560 men in the United States wouldCancer be diagnosed with cancer in 2004. Of these men, 13%Cancer is a disease caused by uncontrolled cell growth. More would be diagnosed withthan 1 million people in the United States are diagnosed with lung cancer. From these sta-cancer every year, and cancer is the second leading cause of tistics, calculate how manydeath in the United States. Cancer is caused by many things, men were predicted to beincluding exposure to certain chemicals. Substances that cause diagnosed with lung cancer in 2004.cancer are called carcinogens (kahr SIN uh juhnz). Table 1 showsa list of common chemical carcinogens.Reading Check What is cancer? (See the Appendix for answers toReading Checks.)Autoimmune DiseasesAn autoimmune disease is a disease in which a person’s immunesystem attacks certain cells, tissues, or organs of the body. The carcinogen a cancer-causingcauses of autoimmune diseases are not well known, but some substancediseases may be caused by exposure to certain chemicals. Forexample, lupus is an autoimmune disease that may be triggeredby certain antibiotics, certain drugs, and hormones. Table 1 Kinds of Carcinogens Carcinogen Body parts that may be affected Asbestos lung, colon, larynx, and gastrointestinal system Alcoholic beverages mouth, pharynx, larynx, esophagus, liver, and breast Arsenic skin, lung, kidney, liver, and gastrointestinal system Benzene bone marrow Coal tar lung, mouth, skin, stomach, larynx, bladder, and bone marrow Radon lung Soots lung, esophagus, liver, and bone marrow Environmental (second- lung hand) tobacco smoke Smokeless tobacco mouth Tobacco smoke lung, bladder, mouth, pharynx, larynx, esophagus, and pancreas Section 3 Chemical Risks 335Copyright © by Holt, Rinehart and Winston. All rights reserved.
    • Figure 2 This little girl has fetalalcohol syndrome (FAS). Hercondition causes her small sizeand distinct facial features. Butthe FAS affects her behavior andmental development the most. Birth Defects Some birth defects are caused when a fetus is exposed to certain chemicals. For example, the child in Figure 2 has fetal alcohol syndrome (FAS). FAS is a group of birth defects that a child may have because his or her mother drank large amounts of alcohol when pregnant. A child with FAS may be small at birth, have brain damage, and be mentally retarded. Other chemicals that are known to cause birth defects are thalidomide (a sedative) and isotretinoin (medicine for acne). Diabetes Diabetes is a disease that affects the body’s ability to use sugar for energy. There are two main types of diabetes. In type 1 diabetes, the body produces little or no insulin. Insulin is a hormone that helps the body store glucose, or sugar. Insulin also enables cells to use glucose for energy. In type 2 diabetes, the body makes insulin but cannot use it properly. People who have type 1 diabetes and some people who have type 2 diabetes must receive daily insulin injections, as shown in Figure 3. The causes of type 1 diabetes are not well known. Some people think that certain vaccines can trigger type 1 diabetes, but no scientific research currently supports this belief. The causes of type 2 diabetes are mostly related to a person’s life- style. People who are overweight and do not exercise regularly are at greatest risk of developing type 2 diabetes. However, certain steroid medicines used to treat asthma and arthritis are known to trigger type 2 diabetes. Learning and Behavioral Disorders Learning and behavioral disorders are caused by many things, including genetics. But some causes are related to chemical exposure. For example, lead poisoning can result in learning and behavioral disorders. Children may get lead poisoning ifFigure 3 This teen is giving they eat paint chips from walls painted with lead-based paints.herself an insulin injection to Thus, peeling paint should be removed from homes wherecontrol her type 1 diabetes. young children live.336 Chapter 11 Chemicals and Our World Copyright © by Holt, Rinehart and Winston. All rights reserved.
    • Kidney DiseaseKidneys are organs that filter water and wastes from theblood. Kidneys can be affected by a variety of diseases. Thesediseases cause the kidneys to function improperly or to failcompletely. Some kidney diseases are caused by exposure tochemicals. For example, pain relievers, such as aspirin andibuprofen, can cause kidney damage if they are used for longperiods of time. Certain combinations of medicines, such as Ozone and Asthma Ozonethe combination of aspirin, acetaminophen, and caffeine, also is a chemical that can formcan damage the kidneys. near the surface of the Earth when air pollutants from carsHeart Disease and power plants react in the presence of heat and sun-Heart disease is a general name for several diseases that affect light. Ground-level ozone canthe heart and the cardiovascular system. Strokes, heart attacks, cause harmful health effects,and atherosclerosis (ATH uhr OH skluh ROH sis) are examples including inflammation of theof heart diseases. Exposure to the chemicals in cigarette smoke lungs and the aggravation of asthma. Research ground-levelcan contribute to the development of heart disease. In addi- ozone, and make a pamphlettion, taking certain illegal drugs, such as cocaine and Ecstasy, for teens who have asthma.can cause heart attacks. In your pamphlet, explain the dangers of ozone and waysReading Check What are three examples of heart disease? for teens to avoid having problems.AsthmaThe teen in Figure 4 is using an inhaler to treat her asthma.Asthma is a disease that causes air passages in the lungs tonarrow. Shortness of breath, wheezing, and coughing are symp-toms of asthma. Allergies, respiratory infections, and chemicalsin the air can cause asthma. Chemicals in cigarette smoke, airpollutants, and aerosol sprays can trigger asthma attacks.Figure 4 Asthma attackscan be triggered by certainchemicals but can be treatedwith other chemicals. Thechemicals in an inhaler helprestore normal breathing. Section 3 Chemical Risks 337Copyright © by Holt, Rinehart and Winston. All rights reserved.
    • Figure 5 Restaurants and otherbusinesses often have rules thatprohibit smoking in certain areas. Reducing Exposure to Dangerous Chemicals Because some chemicals can be harmful to your health, reduc- ing your exposure to them is important for reducing their effects. Luckily, laws and rules help reduce or eliminate the public’s exposure to some dangerous chemicals. And you can do several things to reduce your personal exposure to other harmful chemicals. Laws and Rules to Reduce Exposure The federal government has passed a few laws to help reduce the amount of harmful chemicals released into the environ- ment. Two such laws are the Clean Air Act, which was passed in 1970 and strengthened in 1990, and the Clean Water Act, which was passed in 1972. These acts set standards for accept- For another activity related able levels of pollutants in the air and water. Since these acts to this chapter, go to were passed, some kinds of air pollution and water pollution go.hrw.com and type in the keyword HP5CMPW. in the United States have decreased. Rules that ban smoking in certain public places help reduce people’s exposure to the dangerous chemicals in ciga- rette smoke. In most restaurants, you can avoid secondhand smoke by choosing to sit in a nonsmoking area. You can also avoid secondhand smoke by eating at nonsmoking restaurants, such as the one shown in Figure 5. Smoking is also banned in most public areas of airports and government buildings.  Reading Check Which two laws help reduce people’s exposure to chemical pollutants?338 Chapter 11 Chemicals and Our World Copyright © by Holt, Rinehart and Winston. All rights reserved.
    • Reducing Your ExposureAlthough dangerous chemicals are common, you can takemany simple steps to reduce your exposure to them. Forexample, choosing not to smoke and avoiding peoplewho are smoking can reduce or almost eliminate yourexposure to cigarette smoke. Another way to reduceexposure is to work in a well-ventilated area when youare using chemicals that can produce dangerous fumes.Such chemicals include model-airplane glue and somehousehold cleaners. Also, thoroughly washing fruits andvegetables, as shown in Figure 6, will keep you from Figure 6 Pesticides are often usedaccidentally eating pesticides that were sprayed on the on fruits and vegetables. Washingplants during farming. fruits and vegetables with water removes these chemicals. Using Key Terms Math Skills Review 1. In your own words, write a defi- 7. In one year, 272,810 women nition for the term carcinogen. died from cancer. Of those women, 4% died from leukemia. Understanding Key Ideas How many women died from leukemia? Summary 2. Which of the following carcino- gens can cause liver cancer? Critical Thinking A person may be a. asbestos • exposed to dangerous b. alcoholic beverages 8. Predicting Consequences Suppose your aunt has severe chemicals by eating, c. coal tar back problems. She takes aspirin touching, or inhaling the d. tobacco smoke every day to relieve her pain. chemicals. 3. How can you be exposed to dan- What health problems might Some chemicals can • contribute to certain she be in danger of developing? gerous chemicals? human health condi- a. by touching the chemicals 9. Evaluating Conclusions Your tions, including cancer, b. by inhaling fumes from the friend tells you that he doesn’t autoimmune diseases, chemicals think that smoking is dangerous birth defects, diabetes, c. by eating the chemicals because many smokers live for a learning and behavioral d. All of the above long time. Use the information disorders, kidney dis- that you learned in this section ease, heart disease, and 4. Why should pregnant women to evaluate your friend’s belief. asthma. avoid drinking alcoholic beverages? • ous chemicalsdanger- The effects of can be 5. Name chemicals that may con- reduced or eliminated by tribute to the following health reducing exposure to the conditions: autoimmune disease, chemicals. diabetes, learning and behav- For a variety of links related to this ioral disorders, heart disease, and chapter, go to www.scilinks.org asthma. Topic: Noninfectious Diseases; 6. List three ways that you can Smoking and Health reduce the effects of dangerous SciLinks code: HSM1042; HSM1403 chemicals. 339Copyright © by Holt, Rinehart and Winston. All rights reserved.
    • USING KEY TERMS 8 If a farmer did not use pesticides, his cropsComplete each of the following sen-tences by choosing the correct term a. probably would not grow veryfrom the word bank. quickly. b. could be eaten by insects. chemical carcinogen c. could be poisonous to people. medicine dose potency d. probably would grow quickly. 9 Which of the following statements1 A chemical that is used to cure, pre- about natural chemicals is true? vent, or treat an illness is a . a. All natural chemicals are made by2 The amount of medicine that you take natural processes. at one time is a . b. All natural chemicals are made by the human body.3 Radon is a because it can cause c. All natural chemicals have simple several kinds of cancer. structures.4 Aspirin has a defined composition, so d. All natural chemicals are safe. it is an example of a . 0 A child who has should avoid5 A medicine’s is a measure of how going outside if the level of air good the medicine is. pollution is high. a. kidney disease UNDERSTANDING KEY IDEAS b. asthma c. diabetesMultiple Choice d. birth defects6 Which of the following is most likely a q Which of the following statements natural chemical? about good medicines is true? a. the medicine acetaminophen a. Good medicines are safe. b. the food preservative BHT b. Good medicines are potent. c. the sugar sucrose c. Good medicines have minor side d. the plastic polystyrene effects. d. All of the above7 What kind of medicine could a doctor give you to prevent you from getting the measles? a. hormone c. antacid b. antihistamine d. vaccine342 Chapter 11 Chemicals and Our World Copyright © by Holt, Rinehart and Winston. All rights reserved.
    • i Forming Hypotheses Medicines that you can buy in a store are called over- the-counter medicines. Over-the-counter medicines are considered to be safe to use without supervision by a doctor.Short Answer However, many over-the-counter medi- cines have warnings on their labels.w What are fertilizers, and why are they Why do you think these warnings helpful? are necessary?e Why are the Clean Air Act and the Clean Water Act important? INTERPRETING GRAPHICSr What is sanitation, and why is having The graph below shows the causes of good sanitation important? deaths due to cigarette smoking. Use the graph below to answer the ques-Math Skills tions that follow.t Each 15 mL of a cold medicine con- tains 15 mg of a cough suppressant and 6.25 mg of an antihistamine. 31% According to the medicine’s label, Lung cancer adults should take 30 mL of the 4% Stroke 21% medicine every 6 h to relieve cold Heart disease symptoms. 7% Other cancers a. How much antihistamine is in one 20% dose of the cold medicine? Chronic lung 17% disease b. How much cough suppressant Other diagnoses should an adult take in a 24 h (ex: sudden infant period? death syndrome) CRITICAL THINKING o What is the total percentage of deaths due to smoking-related cancers?y Concept Mapping Use the following terms to create a concept map: natural, p Which cause of death affects the small- medicine, fertilizer, synthetic, chemical, est number of smokers? and preservative. a What percentage of smoking-relatedu Making Inferences A warning on a deaths result from damage to the can of spray paint says to use the prod- lungs? uct in a well-ventilated area. Why do you think such an instruction is on the paint? Chapter Review 343Copyright © by Holt, Rinehart and Winston. All rights reserved.
    • EOG Prep READI NG Read each of the passages below. Then, answer the questions that follow each passage.Passage 1 Heart disease is the leading cause of Passage 2 Your kidneys clean your blood. Theydeath in the United States. Heart disease causes also help regulate the amount of water in yourmore than 900,000 deaths per year. These deaths body. When blood enters a kidney, the blood con-constitute 40% of all deaths in the United States. tains nutrients, gases, water, and waste products.Twenty-five percent of deaths due to heart disease The kidney must remove wastes and excess wateroccur in people under the age of 65. But death from the blood while leaving other substancesrates are improving. Death rates for the 10-year in the blood. Inside your kidneys are nephrons,period ending in 1985 were 30% less than they which are microscopic filters that remove harmfulwere for the previous 10-year period. This decline products from your blood. The nephrons removein mortality is related to a decrease in risk factors the wastes from the blood through the processfor heart disease and improvements in diagnosis of filtration. The waste products are then mixedand treatment. with excess water to form a liquid called urine. The urinary system then removes the urine and1. In the passage, what does constitute mean? excess water from your body. A to propose B to make up 1. What are the main functions of your kidneys? C to follow A to make nephrons and mix water D to concern B to remove urine and excess water from your body2. Which of the following can be inferred from C to remove blood from water and waste the passage? products D to clean your blood and regulate the F The number of deaths due to heart disease amount of water in your body is greater in the United States than in any other country in the world. 2. According to the passage, what are nephrons? G The number of deaths due to heart disease has not changed since 1985. F nutrients in your blood H Changes in risk factors have decreased the G microscopic filters in your kidneys number of deaths due to heart disease. H waste products that must be removed from I Nothing can be done to prevent deaths your blood from heart disease. I parts of the urinary system3. What percentage of deaths due to heart disease 3. According to the passage, what kinds of occur in people under the age of 65? chemicals can be found in your blood? A 10% A water, gases, and nutrients B 25% B urine and water C 30% C nephrons and waste products D 40% D poisons and medicines 344 Chapter 11 Chemicals and Our World Copyright © by Holt, Rinehart and Winston. All rights reserved.
    • I NTE RPRETI NG G RAPH ICS MATH The graph below shows the number of acres Read each question below, and choose the of corn planted and harvested in the United best answer. States. Use the graph below to answer the questions that follow. 1. A medicine that relieves nasal congestion is dispensed in tablets. Each tablet contains 30 mg of the medicine. A dose of the medicine 90 for people who are more than 12 years old is 85 two tablets every 6 h. How much medicineCorn (in millions of acres) Planted does a 15-year-old person take in a 24 h period? 80 A 30 mg 75 B 60 mg 70 C 120 mg D 240 mg 65 60 2. Citric acid is a chemical found in citrus fruits. Harvested The chemical formula of citric acid is C6H8O7. 55 C is the symbol for carbon, O is the symbol for 50 oxygen, and H is the symbol for hydrogen. The 1981 1985 1989 1993 1997 2001 number after each symbol indicates how many Year atoms of the element are in one molecule of Source: U.S. Department of Agriculture. citric acid. What percentage of the atoms in citric acid are oxygen atoms? F 0.33% 1. In which year was the most corn planted? G 7% A 1981 H 33% B 1983 I 50% C 1985 D 1998 3. Peter has a piece of nylon cloth that is 3 m long and 2 m wide. What is the area of the Standardized Test Preparation 2. How many acres of corn were planted in 1993? piece of cloth? F 60 million A 5 m2 G 64 million B 6 m2 H 73 million C 5 m3 I 79 million D 6 m3 3. Which of the following statements summarizes 4. Every year, about 12% of a farmer’s wheat crop the data in the graph? is destroyed by insects. One spring, the farmer plants 60 acres of wheat. How much wheat can A The amount of corn harvested each year the farmer expect to harvest the following fall increased. if no natural disaster strikes the farmer’s crops? B The amount of corn harvested each year F 7 acres was less than the amount of corn planted in that year. G 48 acres C The highest amount of corn was planted in H 53 acres the year when the amount harvested was I 88 acres lowest. D The amount of corn planted decreased every year. Standardized Test Preparation 345 Copyright © by Holt, Rinehart and Winston. All rights reserved.