Chapter 16 Online Study Guide

Carcinogens are substances that can cause cancer. They promote the growth of malignant tumors, which are cancerous tumors. Malignant tumors have the ability to spread to other parts of the body, a process known as metastasis. During metastasis, malignant cells break off from the primary tumor and travel through body fluids to establish secondary tumors in different locations.

Hepatitis B is listed as the seventh deadliest infectious disease in section 16-4.

A poison is defined legally as a chemical that has a lethal dose (LD50) of 50 milligrams or less per kilogram of body weight. This means that if a person were to consume or be exposed to this chemical, it would be potentially lethal if the dosage reaches or exceeds this threshold.

The correct answer is wars. According to the section on HIV/AIDS, the WHO estimates that between 2000 and 2010, AIDS would cause a death toll comparable to that of all the wars in the 20th century combined. This comparison highlights the devastating impact of the HIV/AIDS epidemic on global mortality rates, emphasizing the urgency of addressing and combating the disease.

According to section 16-1, the bodies of most human beings contain small amounts of about 500 synthetic organic chemicals that did not exist in 1920. These chemicals have mostly unknown health effects.

PCBs, or polychlorinated biphenyls, are a class of synthetic chemicals that were commonly used in electrical transformers. They were used as coolants and insulating fluids in these devices. Over time, it was discovered that PCBs are toxic and harmful to both human health and the environment. Therefore, the main source of PCBs, as mentioned in the question, is electrical transformers.

The correct answer is 99.5 because according to Section 16-3, federal and state governments do not regulate about 99.5% of the commercially used chemicals in the United States. These unregulated chemicals can end up in our water sources, posing potential harm to human health and the environment. This highlights the limited knowledge and control we have over the harmful effects of these chemicals.

Cholera is not a viral disease. It is caused by the bacterium Vibrio cholerae, which is typically transmitted through contaminated food or water. Cholera leads to severe diarrhea and dehydration, and can be life-threatening if left untreated. Ebola, rabies, and HIV, on the other hand, are all viral diseases caused by the Ebola virus, the rabies virus, and the human immunodeficiency virus (HIV) respectively.

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Lead is a neurotoxin because it has the ability to damage the nervous system, particularly the brain. When lead enters the body, it can interfere with the normal functioning of neurons and disrupt the transmission of signals between cells. This can lead to a range of neurological symptoms and impairments, such as cognitive deficits, developmental delays, and behavioral problems. Therefore, lead is considered a neurotoxin due to its harmful effects on the nervous system.

Approximately 1,180 Americans are killed each day due to cigarette smoking. This statistic highlights the significant impact that smoking has on public health. Smoking is a leading cause of preventable deaths and is associated with various health issues such as lung cancer, heart disease, and respiratory problems. The high number of deaths emphasizes the urgent need for effective tobacco control measures and smoking cessation programs to reduce the harm caused by smoking.

Approximately 20,000 people die each year from the flu in the United States.

The LD50 (lethal dose 50) is a measure of the toxicity of a substance, indicating the dose at which 50% of the test population would be expected to die. In the given question, the table classifies nicotine as extremely toxic, suggesting that it has a low LD50. Therefore, when comparing the options, the correct answer is botulism toxin, as it is implied to have an even lower LD50 than nicotine.