ADENOCARCINOMA A malignant tumor formed from glandular structures in epithelial tissue. It is the predominant cell type in breast, pancreatic, prostate, and colorectal cancers. Adenocarcinoma of the cervix is the second most common type after squamous cell carcinoma.
AFLATOXIN Poisonous and cancer-causing chemicals that are produced by certain molds which grow in soil, decaying vegetation, hay, and grains. They are regularly found in improperly stored staple commodities such as cassava, chili peppers, corn, cotton seed, millet, peanuts, rice, sorghum, sunflower seeds, tree nuts, wheat, and a variety of spices.
ALKYLPHENOLS Class of organic compounds. Long-chain alkylphenols are used extensively as precursors to the detergents and are also used in making many industrial and consumer products. They have received attention for their weak endocrine effects.
ANTIBODY A protein produced by the immune system to identify and neutralize pathogens such as bacteria and viruses. The antibody recognizes a unique molecule of the harmful agent, called an antigen.
ASSOCIATION A correlation between an exposure, or a characteristic, and a disease. Association is a necessary condition for a causal relationship, but many phenomena are associated without one of them causing the other. Hence the dictum “association does not prove causation.”
ATRAZINE A common herbicide used on important food crops such as corn, sorghum, and sugar cane.
AVAILABILITY CASCADE A self-reinforcing process of collective belief formation by which an expressed perception triggers a chain reaction that gives the perception of increasing plausibility through its rising availability in public discourse.
AVAILABILITY HEURISTIC A mental shortcut that relies on immediate examples that come to a given person’s mind when evaluating a specific topic, concept, method, or decision.
BAYES’ THEOREM A valuable tool for judging how a subjective degree of belief should rationally change to account for available evidence. Bayes’ theorem describes the probability of an event, based on conditions that might be related to the event. For example, suppose one is interested in whether a woman has cancer, and knows that she is 65. If cancer is related to age, information about her age can be used to more accurately assess the probability of her having cancer using Bayes’ theorem.
BIAS Deviation of results or inferences from the truth, or processes leading to such deviation. Any trend in the collection, analysis, interpretation, or review of data that can lead to conclusions that are systematically different from the truth.
BISPHENOL A (BPA) Compound used to line food containers and in the manufacture of polycarbamate plastics.
CARCINOMA A type of cancer that develops from epithelial cells, that is, in a tissue that lines the inner or outer surfaces of the body. These are the most common types of cancer.
CASE-CONTROL STUDY Type of study in which cases of a particular disease are identified and a comparison group without the disease (controls) is identified. Information on factors thought to play a role in the disease is obtained from both groups and compared. Case-control studies are particularly useful in studying uncommon diseases.
CAUSALITY Agency or efficacy that connects one process with another, where the first is understood to be partly responsible for the second.
CAUSATION A means of connecting an event or exposure with a resulting effect.
COHORT STUDY Study in which information relevant to the risk of developing disease is collected from members of a defined population, or “cohort.” The cohort is then followed for a number of years, and cases (or deaths) of the disease of interest are identified. Factors associated with the development of disease can then be evaluated.
COMPLEMENTARY AND ALTERNATIVE MEDICINE (CAM): ALTERNATIVE MEDICINE is any practice that is put forward as having the healing effects of medicine but does not originate from evidence gathered using the scientific method, is not part of biomedicine, or is contradicted by scientific evidence or established science.
COMPLEMENTARY MEDICINE is alternative medicine used together with conventional medical treatment, in a belief, not confirmed using the scientific method, that it “complements” (improves the efficacy of) the treatment.
CONFIDENCE INTERVAL A measure of the reliability of a risk estimate. A 95 percent confidence interval means that 95 times out of 100 the estimated risk will fall within the specified interval.
CONFOUNDING, CONFOUNDING FACTOR The distortion of an observed association between a factor of interest and a disease by a third factor that is associated with both the study factor and the disease.
CRITERIA OF JUDGMENT A set of considerations elaborated by the statistician Austin Bradford Hill relevant to judging whether an observed association is causal. These include the strength of the association, the consistency of the association observed in different studies, temporality (whether the exposure precedes the occurrence of disease), and biological plausibility.
CRYPTORCHIDISM (UNDESCENDED TESTES) The failure of one or both of the testicles to move down from the abdomen into the scrotum. It is the most common birth defect of the male genitalia.
CYTOLOGY The study of cells; more specifically, in the context of cervical cancer, the examination of cells obtained via Pap testing to identify cancerous changes.
DDT (DICHLORODIPHENYLTRICHLOROETHANE) An organochlorine compound widely used as an agricultural insecticide following World War II. DDT was banned in the United States for agricultural use starting in 1972.
DEMING The high rate of publication of results from observational studies that cannot be replicated. The term refers to Edwards Deming, an innovator in quality control in the automobile industry, who argued that (1) a system that is out of control is not the fault of the workers, it is the fault of the managers that designed and run the system; and (2) it is the responsibility of managers to fix the system.
DIETARY SUPPLEMENTS Dietary supplements include vitamins, minerals, herbals and botanicals, amino acids, enzymes, and many other products.
DIETARY SUPPLEMENT AND HEALTH EDUCATION ACT (DSHEA) A U.S. federal statute, passed in 1994, which defines vitamin, mineral, herbal, and other products as “dietary supplements.” Dietary supplements are exempt from the rigorous standards that apply to drugs, and manufacturers are not required to provide evidence of safety or efficacy in order to market a product.
DIETHYLSTILBESTROL (DES) A synthetic, nonsteroidal estrogen that was administered to pregnant women in the middle of the twentieth century to prevent miscarriage.
DIOXIN The common name for the chemical 2,3,7,8-tetrachlorodibenzo-p-dioxin, or TCDD. The term “dioxins” refers to a group of dioxin-like chemical compounds that share similar chemical structures. Most dioxins are produced through burning and other industrial activities. They are highly toxic and persistent in the environment and accumulate exponentially as they move up the food chain.
DNA ADDUCT A piece of DNA covalently bonded to a (cancer-causing) chemical. This process could be the start of a cancerous cell, or carcinogenesis.
DOSE-RESPONSE RELATIONSHIP The change in risk of disease (response) as exposure to the factor of interest (dose) increases. The number of cigarettes smoked per day by smokers shows a classic dose-response relationship with their risk of lung cancer.
EBOLA A rare and deadly disease caused by infection with a strain of Ebola virus, first identified in 1976 in Central Africa. The Ebola epidemic in 2014 was the largest in history, affecting multiple countries in West Africa. The risk of an Ebola outbreak affecting large numbers of people in the United States is very low.
ELECTROMAGNETIC FIELD (EMF) A physical field produced by electrically charged objects. It affects the behavior of charged objects in the vicinity of the field. The electromagnetic field extends indefinitely throughout space and describes the electromagnetic interaction.
ELECTROMAGNETIC SPECTRUM The range of all possible electromagnetic radiation from gamma rays, with very high frequencies and energies, to extremely low-frequency fields from power lines and electric appliances that have very low energy levels.
ENDOCRINE DISRUPTING CHEMICALS Term used to identify chemicals in the environment that can interfere with normal hormonal pathways, including estrogen, testosterone, and thyroid hormones. However, the label is often used loosely based on limited studies that are often not applicable to real-world exposure and do not distinguish between irreversible effects and transient effects. The term often presupposes that which it aims to prove.
ENDOCRINE DISRUPTION Exposure to certain drugs or possibly to chemicals in the environment can disrupt the endocrine system by mimicking a natural hormone, by blocking the effects of a hormone from certain receptors, or by directly stimulating or inhibiting the endocrine system and causing overproduction or underproduction of hormones.
ENVIRONMENT Used in the health sciences to refer broadly to exposures other than genetic inheritance. Thus the term includes not just industrial pollution but other “external” exposures, including diet, smoking, microbes, drugs, etc.
EPITHELIAL TISSUE A sheet of cells that covers a body surface, such as the skin, or lines organs, such as the lungs and digestive tract.
ESTRADIOL More precisely, 17β-estradiol, a steroid and estrogen sex hormone, and the primary female sex hormone. It is named for and is important in the regulation of the estrous and menstrual female reproductive cycles.
EXPOSURE The condition of having contact with a physical or chemical agent in such a way that the contact can influence the development of disease.
FALSE POSITIVE RESULT A result, showing a positive association, that proves to be wrong when evaluated using better evidence.
FERTILITY The natural capability to produce offspring. As a measure, fertility rate is the number of offspring born per mating pair, individual, or population.
FRACKING (HYDRAULIC FRACTURING) The process of drilling and injecting fluid into the ground at a high pressure in order to fracture shale rocks to release natural gas inside.
FREQUENCY (ELECTROMAGNETIC WAVES) Number of oscillations per unit time, i.e., number of cycles per second (hertz).
GENETIC MODIFICATION Also called genetic engineering. The direct manipulation of an organism’s genome using biotechnology. It is a set of technologies used to change the genetic makeup of cells, including the transfer of genes within and across species boundaries to produce improved or novel organisms.
GENOME-WIDE ASSOCIATION STUDY (GWAS) An approach that involves rapidly scanning markers across the complete sets of DNA, or genomes, of many people to find genetic variations associated with a particular disease.
GENOMICS A discipline in genetics that applies recombinant DNA, DNA sequencing methods, and bioinformatics to sequence, assemble, and analyze the function and structure of genomes (the complete set of DNA within a single cell of an organism).
GLIOMA Type of primary brain tumor, accounting for about one-third of all brain tumors. Gliomas originate in the glial cells, which surround and support neurons in the brain. Glioma is the most fatal type of brain tumor.
GLYPHOSATE A broad-spectrum systemic herbicide and an organophosphorus compound, used to kill weeds, especially annual broadleaf weeds and grasses that compete with crops.
HAZARD The potential of an exposure to cause harm and adverse effects.
HAZARD IDENTIFICATION Identification of a potential risk due to a particular compound or agent.
HEAD AND NECK CANCER Cancers that usually begin in the squamous cells that line the moist, mucosal surfaces inside the head and neck, including the mouth, pharynx, larynx, and esophagus.
HELICOBACTER PYLORI A bacterium found usually in the stomach that is also linked to the development of duodenal ulcers and stomach cancer.
HERPES SIMPLEX VIRUS 2 (HSV-2) Member of the herpesvirus family that infect humans. HSV-2 (which produces most genital herpes) is ubiquitous and contagious.
HEURISTIC Any approach to problem solving, learning, or discovery that employs a practical method not guaranteed to be optimal or perfect but sufficient for the immediate goals. Heuristics can be mental shortcuts that ease the cognitive load of making a decision. Examples of this method include using a rule of thumb, an educated guess, an intuitive judgment, stereotyping, profiling, or common sense.
HORMONE Any member of a class of signaling molecules produced by glands in multicellular organisms that are transported by the circulatory system to target distant organs to regulate physiology and behavior.
HUMAN PAPILLOMAVIRUS (HPV) A DNA virus from the papillomavirus family that is capable of infecting the skin and mucous membranes of humans.
HYPOSPADIAS A birth defect of the urethra in the male where the urinary opening is not at the usual location on the head of the penis. It is the second most common birth abnormality in boys, affecting approximately 1 of every 250.
INCIDENCE RATE The frequency of newly diagnosed cases of a disease within a period of time (usually one year). Cancer incidence is often reported in terms of the number of new cases per hundred thousand population.
INFERENCE Drawing conclusions about a population using data drawn from the population by means of sampling.
IN SITU HYBRIDIZATION A powerful technique that uses a labeled complementary DNA, RNA, or modified nucleic acids strand (i.e., probe) to localize a specific DNA or RNA sequence in a portion or section of tissue (in situ), providing insights into physiological processes and disease pathogenesis.
INTERNATIONAL AGENCY FOR RESEARCH ON CANCER (IARC) An arm of the World Health Organization, which conducts cancer research and publishes assessments of potential cancer causing substances.
INTERNATIONAL COMMITTEE ON NON-IONIZING RADIATION PROTECTION (ICNIRP) An independent organization that provides scientific advice and guidance on the health and environmental effects of non-ionizing radiation to protect people and the environment from detrimental non-ionizing radiation.
INTERPHONE STUDY A large international case-control study led by IARC to examine the association of mobile phone use and brain tumors.
IONIZING RADIATION Electromagnetic radiation with sufficient energies to dislodge electrons from an atom, thereby producing an ion pair. Ionizing radiation includes gamma rays, X-rays, and alpha-particles, which can damage DNA through ionization.
ISOFLAVONE A type of phytoestrogen, or plant hormone, that resembles human estrogen in chemical structure yet is weaker.
MENINGIOMA A diverse group of tumors arising from the meninges, the membranous layers surrounding the central nervous system. These tumors are usually benign; however, a small percentage are malignant.
META-ANALYSIS A technique used to combine the results of a number of small studies in order obtain a summary estimate (basically, a weighted average of the smaller studies), which, it is hoped, will better describe the association. Meta-analysis can be carried out using the data available from published papers, in contrast to pooled analyses, which involve reanalyzing the original data from different studies using a common approach.
METABOLISM The set of life-sustaining chemical transformations within the cells of living organisms. These enzyme-catalyzed reactions allow organisms to grow and reproduce, maintain their structures, and respond to their environments. The word metabolism can also refer to all chemical reactions that occur in living organisms, including digestion and the transport of substances into and between different cells.
MICROWAVES A form of electromagnetic radiation with wavelengths ranging from one meter to one millimeter; with frequencies between 300 MHz (100 cm) and 300 GHz (0.1 cm). The prefix “micro” indicates that microwaves have “small” wavelengths compared to waves used in typical radio broadcasting.
MUTATION A permanent alteration of the nucleotide sequence of the genome of an organism, virus, or extrachromosomal DNA or other genetic elements.
NEPHROTOXIN A toxic agent or substance that inhibits, damages, or destroys the cells and/or tissues of the kidneys.
NONMONOTONIC DOSE-RESPONSE (NMDR) Controversial concept according to which exposure to a compound at a low level can have a greater effect than exposure at a higher level. This contrasts with the widely accepted notion of a monotonic dose-response relationship in which greater exposure is associated with larger effects. NMDR is currently being evaluated by the U.S. Environmental Protection Agency.
OBSERVATIONAL STUDY A study in which subjects are enrolled and provide information about their health history and exposures and personal habits, which is then correlated with information about the development of a disease(s) of interest. This type of study is contrasted with an experimental study, such as a randomized controlled clinical trial, in which the researcher allocates participants to either the intervention group or the control (placebo) group.
OCHRATOXIN A group of fungal toxins produced by some Aspergillus species and some Penicillium species. Ochratoxin A is the most prevalent and relevant fungal toxin of this group.
ODDS RATIO The measure of association obtained from a case-control study, compares the “odds” of exposure to the factor of interest among cases to the odds of exposure among the controls.
ONCOGENE A gene that in certain circumstances can transform a cell into a tumor cell.
ORAL CANCER/ORAL CAVITY CANCER Can develop in any part of the oral cavity (the mouth and lips) or the oropharynx (the part of the throat at the back of the mouth).
ORGANOCHLORINE COMPOUNDS A wide range of chemicals that contain carbon, chlorine, and sometimes several other elements. A range of organochlorine compounds have been produced, including many herbicides, insecticides, fungicides, as well as industrial chemicals such as polychlorinated biphenyls (PCBs).
OROPHARYNX Part of the throat at the back of the mouth.
PAP TEST (PAPANICOLAOU TEST) A method of cervical screening, known earlier as Pap smear, cervical smear, or smear test, used to detect potentially precancerous and cancerous processes in the cervix (opening of the uterus or womb).
PHARMACOKINETIC MODEL A mathematical modeling technique for predicting the absorption, distribution, metabolism, and excretion (ADME) of synthetic or natural chemical substances in humans and other animal species. PBPK modeling is used in pharmaceutical research and drug development, and in health risk assessment for cosmetics or general chemicals.
PHYTOESTROGENS Plant-derived xenoestrogens not generated within the endocrine system but consumed by eating phytoestrogenic plants. Also called “dietary estrogens,” they are a diverse group of naturally occurring nonsteroidal plant compounds that, because of their structural similarity with estradiol (17-β-estradiol), have the ability to cause estrogenic or/and antiestrogenic effects by sitting in and blocking receptor sites against estrogen.
POLYCHLORINATED BIPHENYLS (PCBs) A group of man-made compounds that were widely used in the past, mainly in electrical equipment, but were banned at the end of the 1970s in many countries because of environmental concerns.
POLYMERASE CHAIN REACTION (PCR) A technology in molecular biology used to amplify a single copy or a few copies of a piece of DNA across several orders of magnitude, generating thousands to millions of copies of a particular DNA sequence.
PRECAUTIONARY PRINCIPLE Approach to risk management that states that if an action or policy has a suspected risk of causing harm to the public or to the environment, in the absence of scientific consensus that the action or policy is not harmful, the burden of proof that it is not harmful falls on those taking an action.
PROSPECTIVE STUDY See cohort study.
RADIATION Energy emitted in the form of waves or particles by radioactive atoms as a result of radioactive decay.
RADIOFREQUENCY (RF) WAVES Another name for radio waves. This form of electromagnetic energy consists of waves of electric and magnetic energy moving together (radiating) through space. RF wave frequencies lie in the range extending from around 3 kHz to 300 GHz, which include those frequencies used for communications or radar signals.
RECALL BIAS Differential reporting of exposure information by cases and controls in a case-control study. May be due to cases’ desire to find an explanation for their diagnosis or to the effects of disease on their recall of past events.
RELATIVE RISK The ratio of the risk of disease or death among the exposed to the risk among the unexposed.
RENAL CORTEX The outer portion of the kidney where ultrafiltration occurs.
RENAL PELVIS Part of the kidney that serves as a funnel for urine flowing into the ureter.
RISK The probability that an event will occur, e.g., the probability that an individual will become ill or die within a stated period of time or by a certain age.
RISK ASSESSMENT The determination of quantitative or qualitative estimate of risk related to a concrete situation and a recognized threat (also called hazard).
RISK FACTOR A personal characteristic or exposure that in an epidemiologic study is associated with the occurrence of disease. Often the term is used to imply a causal relationship, when this is not appropriate.
SPECIFIC ABSORPTION RATE (SAR) Rate at which RF energy is absorbed by human tissues.
SELECTION BIAS Error due to systematic differences in characteristics between those who take part in a study and those who do not. Selection bias can invalidate conclusions and generalizations that might otherwise be drawn from a study.
SEROLOGY The scientific study of serum and other bodily fluids. In practice, the term usually refers to the diagnostic identification of antibodies in the serum.
SINGLE NUCLEOTIDE POLYMORPHISM (SNP) A variation in a single nucleotide that may occur at some specific position in the genome, where each variation is present to some appreciable degree within a population (e.g., greater than 1%).
SQUAMOUS CELL CARCINOMA A cancer of one type of epithelial cell, the squamous cell. Squamous cells are the main part of the skin but also occur in the lining of the digestive tract, lungs, and other areas of the body, and squamous cell carcinoma occurs in diverse tissues, including the lips, mouth, esophagus, urinary bladder, prostate, lung, vagina, and cervix, among others.
STATISTICAL POWER The ability of a study to detect a statistically significant association between an exposure and a disease of interest. Statistical power depends on the size of the study and how well the factors and the disease condition have been measured (i.e., on the quality of the data).
STATISTICAL SIGNIFICANCE A measure of whether a particular result is unlikely to be due to chance. If the 95 percent confidence interval associated with a relative risk (or odds ratio) does not include 1.0, the result is conventionally judged to be statistically significant.
TESTICULAR DYSGENESIS SYNDROME (TDS) A group of abnormalities of the male reproductive system including testicular cancer, impaired semen quality, undescended testis, and hypospadias.
TRANSPLACENTAL CARCINOGENESIS A series changes in the cells of a fetus due to in utero exposure to carcinogens that can result in the development of cancer.
TUMOR SUPPRESSOR GENE Gene that protects a cell from one step on the path to cancer. When this gene mutates to cause a loss or reduction in its function, the cell can progress to cancer, usually in combination with other genetic changes.
UPPER UROTHELIAL CANCER, OR UPPER URINARY TRACT CANCER Cancers of the upper urinary tract are relatively rare. In 2015 about 3,100 Americans will be diagnosed with this cancer. The most common of all upper urinary tract cancers are those found in the renal pelvis and renal calyces. Cancer in the ureters makes up about a quarter of all upper urinary tract cancers.
UROTHELIAL CANCER Cancer of the urinary system: predominantly those of the bladder, ureter, and urethra, but also less commonly in the kidney. These are transitional cell cancers and are distinct from renal cell cancers, which are the most common type of kidney cancer.
WEIGHT-OF-THE-EVIDENCE ASSESSMENT An approach used to integrate evidence from multiple lines of investigation in order to draw conclusions about a potential risk to a population.