the information site on endocrine disruption

This section is designed to introduce some key terms commonly used in endocrine modulator related discussions.

Adrenal Glands : : The suprarenal or adrenal glands, each perched over one of the kidneys, are double glands. The core, or medulla, manufactures adrenalin, noradrenalin and a small amount of dopamine. These chemical messengers are also produced by the nerve endings of the sympathetic nervous system. The outer layer of the gland is called the cortex. The adrenal cortex produces three groups of corticosteroids; mineralocorticoids (aldosterone) - control electrolyte and water balance, glucocorticoids (cortisol)- influence carbohydrate metabolism and sex steroid hormones (androgens, DHEA).

Androgen / Anti-Androgen
: Androgens are the natural sex hormones of male animals, responsible for development of an animal in the male form and for the development of secondary sexual characteristics at puberty (e.g. hair and muscle growth, deepening of the voice.) The major androgen is testosterone. Anti-androgens are substances which block the function of normal androgens. They bind just like normal androgens to androgen receptors, but unlike androgens, this binding does not result in activation of the receptors. Thus anti-androgens block the receptors from stimulation by androgens. Science & Issues

Anthropogenic: Anthropogenic is a term of or relating to the study of the origins and development of human beings.

Biomarker:  1. Indicator signaling an event or condition in a biological system or sample and giving a measure of exposure, effect, or susceptibility. As related to biomonitoring, a biomarker is the presence of any substance, or a change in any biological structure or process that can be measured as a result of exposure. Many biomonitoring studies focus on chemical substances or their metabolites as biomarkers. (

Bio-monitoring: Continuous or repeated measurement of potentially toxic substances, their metabolites or their biochemical effects in tissues, secreta, excreta, expired air or any combination of these. Its purpose is to evaluate occupational or environmental exposure and health risk by comparison with appropriate reference values based on knowledge of the probable relationship between ambient exposure and resultant adverse health effects (

Biotransformation is the process whereby a substance is changed from one chemical to another (transformed) by a chemical reaction within the body.

Congener: Member of a chemical family.

Cryptorchidism: In the male fetus, the testicles develop in the abdominal cavity and descend into the scrotum before birth. Cryptorchidism, or undescended testicles, occurs when one or both testicles fail to move into the scrotum prior to birth. Undescended testicles are fairly common in premature infants, and occur in about 3 to 4% of full-term infants. About 65% of the testicles typically descend by 9 months of age. Cryptorchidism is a risk factor for the later development of testicular cancer. Summary Fact sheet

Differentiation: The acquisition of specialized or tissue specific function by immature cells.

Dose-Response Assessment: The second of four steps in risk assessment, consisting of the analysis of the relationship between the total amount of an agent absorbed by a group of organisms and the changes developed in the group in reaction to the agent, and inferences derived from such an analysis with respect to the entire population. (

Endocrine disrupter : : An exogenous substance or mixture that alters function(s) of the endocrine system and consequently causes adverse health effects in an intact organism, or its progeny, or (sub) populations. Science & Issues

Endocrine toxicant: A term suggested to describe chemicals that disrupt endocrine homeostasis and induce adverse health effects.

Endocrine modulator : Another term used to describe modulation of the endocrine system by an exogenous substance. See also Endocrine Disrupter/Hormonally Active Agents

Endocrine system : A network of glands distributed throughout the body forms the endocrine system. These glands produce hormones that are released into the circulation and distributed to distant target sites via the blood. Hormones produced by these glands act as chemical messengers to control body functions such as growth, metabolism, sexual development, and egg and sperm production.

Endogenous: Something (ie. Chemical, hormone) originating or produced within the organism.

Environmental Estrogen: Phytoestrogens (plant based estrogens found in such plants as soya, beans, grains) and the man-made chemicals that are found in the environment and have estrogenic properties. See also Endocrine Disrupter/Endocrine Modulator/ Hormonally Active Agents

Epidemiological Studies:  studies on human populations, which attempt to link human health effects (e.g. cancer) to a cause (e.g. exposure to a specific chemical). (

Exogenous: Something (ie. Chemical, hormone) originating or produced outside of the organism.

Exposure Assessment: Quantitative or qualitative evaluation of the contact of a chemical with the outer boundary of the human body, which includes consideration of the intensity, frequency and duration of contact, the route of exposure (e.g. dermal, oral or respiratory), rates (chemical intake or uptake rates), the resulting amount that actually crosses the boundary (dose), and the amount absorbed (internal dose) (WHO 1999). (

Exposure Misclassification: occurs when an exposed individual is classified as unexposed and vise versa. (Aschengrau, 2003)

Fertility and fecundity: Fecundity is the potential ability of a couple to conceive a child whereas fertility refers to the ability to conceive and is evaluated by the time to achieve pregnancy. Primary infertility is the term used to describe a couple that has never been able to conceive a pregnancy, after a minimum of 1 year of attempting to do so through unprotected intercourse. Secondary infertility is the term used to describe couples who have previously been pregnant at least once, but have not been able to achieve another pregnancy. Summary Fact sheet

Hazard Identification: The identification of known or potential health effects associated with a particular agent. (

Hormonally Active Agents (HAAs): Another term for endocrine disrupter, preferred by some because it does not deal with the mechanistic nature of the chemical and it does not require an evaluation of the chemical's mechanism of action. See also Endocrine Disrupter/Endocrine Modulator

Hormones : Chemical messengers that help our body do different tasks. Hormones are produced by the endocrine glands and then sent all over the body to stimulate certain activities. For example, Insulin is a well-known hormone that helps our body digest food. Hormones regulate our growth, digestion, reproduction and sexual functions. Endocrine Primer

Hypospadias: Hypospadias is a relatively common congenital abnormality in which the opening of the urethra is on the underside, rather than at the end, of the penis. This condition affects up to 3 in 1,000 newborn boys and varies in severity. In most cases, the opening of the urethra is located near the tip of the penis on the glans, however, more severe forms of hypospadias occur when the opening is at the midshaft or the base of the penis. Occasionally the opening is located in the scrotum or the perineum (beneath the scrotum). Summary Fact sheet

Hypothalamus : The hypothalamus contains vital centres for controlling the autonomic nervous system, body temperature and water and food intake, and is the centre for primitive physical and emotional behaviour. The hypothalamus produces hormones for regulating pituitary secretion and two systemic hormones (oxytocin and vasopressin). Endocrine Primer

Laparoscopy: A surgical procedure that allows for the direct visualization of the peritoneal cavity, ovaries, outside of the tubes and uterus using an instrument that acts as a mini-telescope

Male reproductive tract abnormalities: Sexual differentiation is a complicated, hormone-dependent process that determines whether a fetus becomes male or remains female (the default state). This process is triggered by a series of events that must occur with precision and coordination to develop the male reproductive system and associated secondary sexual characteristics. Two common male reproductive tract abnormalities are cryptorchidism, undescended testes after the age of one, and hypospadias, a common abnormality of the penis that appears as an abnormal opening on the underside of the penis rather than at the end. Summary Fact sheet

Metabolite: Any intermediate or product resulting from metabolism (physical and chemical processes occuring within an organism). (

Non-Persistent Chemicals: a substance that is readily removed from an environment through physical, chemical or biological processes. (

Ovaries : These double organs are the female sex glands. The ovaries produce the egg cells (oocytes). The ovaries are important endocrine glands that produce estrogens and progesterone. These hormones help regulate the ovulatory cycle leading to the maturation and ovulation of a mature egg as well as help prepare and maintain the uterus during pregnancy. At puberty, estrogens give rise to secondary sexual characteristics (ie. Breasts, pubic hair etc). Endocrine Primer

Pancreas : The islets of the pancreas produce hormones necessary for the regulation of blood sugar levels- insulin and glucagon. The alpha cells of the islets secrete glucagon, which raises blood glucose (sugar) levels by stimulating the breakdown of liver glycogen. When blood sugar levels are too high, the beta cells of the pancreas secrete insulin which stimulates the uptake of glucose. Endocrine Primer

Parathyroid : The parathyroids are four small glands attached to the thyroid gland, which act to maintain normal levels of calcium and phosphate in the blood and thus normal function of muscles and nerves. Endocrine Primer

Persistent Chemicals: chemical substances that persist in the environment, bioaccumulate through the food web, and pose a risk of causing adverse effects to human health and the environment. This group of priority pollutants consists of pesticides (such as DDT), industrial chemicals (such as polychlorinated biphenyls, PCBs) and unintentional by-products of industrial processes (such as dioxins and furans). (

Pituitary: The hypophysis or pituitary gland is the master gland of the body. Compared with other endocrine glands, it produces the largest number of hormones, including some that control the other endocrine glands of the body. Endocrine Primer

Precocious puberty:
Premature development of body characteristics that normally occur during puberty (the period in life at which rapid physical and physiologic changes occur, including development of reproductive capability). Puberty normally occurs between 13 and 15 years old in boys and between 9 and 16 years old in girls. Summary Fact sheet

Preeclampsia: Preeclampsia is the development of swelling, elevated blood pressure and protein in the urine during pregnancy. The exact cause of preeclampsia has not been identified. Numerous theories of potential causes exist, including genetic, dietary, vascular (blood vessel), and autoimmune factors. Preeclampsia occurs in approximately 8% of all pregnancies with an increased risk associated with first pregnancies.

Phytoestrogens: Plant based estrogens found in such plants as soya, beans, grains.

Polymorphism: Difference in DNA sequence among individuals that may underlie differences in health. Genetic variations occurring in more than 1% of a population would be considered useful polymorphisms for genetic linkage analysis.

Risk Characterization:  Integration of hazard identification, hazard characterization and exposure assessment into an estimation of the adverse effects likely to occur in a given population, including attendant uncertainties. (

Sex ratio: The sex ratio is defined as the number of live male births divided by the total number of births for a given period of time. It is generally assumed that the sex ratio is stable over long periods of time with about 50:50 male:female. Summary Fact sheet

Spontaneous abortion: Commonly called "miscarriage", spontaneous abortion is a pregnancy lost prior to viability, typically defined as 20 weeks from first day of last menstrual period of a fetus weighing less than 500 g. Incidence of spontaneous abortion is estimated to be 50% of all pregnancies, based on the assumption that many pregnancies occur with no clinical recognition. Summary Fact sheet

Testes : These double organs are the male sex glands. The testes in males produce the male germ cells, spermatozoa or simply, sperm. The testes are also important endocrine glands that produce male sex hormones such as testosterone and other androgens. These hormones are important for the regulation of spermatogenesis (production of sperm), sexual differentiation of the male fetus, and the development of secondary sexual characteristics such as hair growth, voice changes etc. Endocrine Primer

Testicular cancer : Testicular cancer can be broadly classified into two types: seminoma and nonseminoma. Seminomas make up about 30 percent of all testicular cancers. Nonseminomas are a group of cancers that include choriocarcinoma, embryonal carcinoma, teratoma, and yolk sac tumors. A testicular cancer may have a combination of both types. Risk factors for testicular cancer include cryptorchidism, Klinefelter's syndrome and abnormal testicular development. Summary Fact sheet

Thymus : : The thymus is of utmost importance in the body's defences against infection, for in the first few weeks of life the lymphocytes produced in it migrate into the bloodstream and colonize lymph nodes all over the body. Lymphocytes manufacture antibodies and are vital for immunity. Endocrine Primer

Thyroid : The thyroid gland consists of two bodies like small walnuts; they are connected by an isthmus beside the larynx (voice box). The thyroid gland produces thyroid hormones T3 and T4 which regulate the metabolism of all cells in the body. Disorders of the thyroid gland are characterized by the inability to produce or release sufficient thyroid hormones (hypothyroidism) or the overactivity of the thyroid gland (hyperthyroidism). Endocrine Primer Summary Fact sheet

Water soluble: the ability of a substance to be dissolved in water. (

©copyright McLaughlin Centre, Institute of Population Health, University of Ottawa