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Toxicology Glossary - D

death rate: Estimate of the proportion of a population which dies during a specified period. The numerator is the number of persons dying during the period; the denominator is the size of the population, usually estimated as the mid-year population. The death rate in a population is generally calculated by the formula: This rate is an estimate of the person-time death rate, the death rate per 10n person-years: usually n = 3. If the rate is low, it is also a good estimate of the cumulative death rate. This rate is also called the crude death rate
Last, 1988
PS mortality, mortality rate

decompensation: Explicit pathophysiological changes following compensation for adverse effects

decontamination: Process of rendering harmless (by neutralization, elimination, removal etc.) a potentially toxic substance in the natural environment, laboratory areas, the workplace, other indoor areas, clothes, food, water, sewage etc

defoliant: Substance used for removal of leaves by its toxic action on living plants

dehydrogenase: Enzyme which catalyses oxidation of compounds by removing hydrogen

delayed effect: Consequence occurring after a latent period following the end of exposure to a toxic substance or other harmful environmental factor
SN latent effect

denaturation:

1. Addition of methanol or acetone to alcohol to make it unfit for drinking
2. Change in molecular structure of proteins so that they cannot function normally, often caused by splitting of hydrogen bonds following exposure to reactive substances or heat

denitrification: Reduction of nitrates to nitrites, nitrous oxides or dinitrogen (N₂) catalysed by facultative aerobic soil bacteria under anaerobic conditions
Nagel et al. (eds),1990

dental fluorosis: Variety of tooth enamel malformations due to excessive fluoride exposure during dental development

deoxyribonucleic acid (DNA): Constituent of chromosomes which stores the hereditary information of an organism in the form of a sequence of purine and pyrimidine bases: this information relates to the synthesis of proteins and hence it is a determinant of all physical and functional activities of the cell, and consequently of the whole organism
RT ribonucleic acid (RNA)

dependence:

1. A psychic craving for a drug or other substance which may or may not be accompanied by a physical dependency
2. Reliance on a drug or other substance to maintain health
   PS addiction

depilatory: Substance causing loss of hair

deposition:

1. Process by which a substance arrives at a particular organ or tissue site, for example the deposition of particles on the ciliated epithelium of the bronchial airways.
2. Process by which a substance sediments out of the atmosphere or water and settles in a certain place
   PS accumulation

dermal: Pertaining to the skin
SN cutaneous

dermal irritation: Skin reaction resulting from a single or multiple exposure to a physical or chemical entity at the same site, characterised by the presence of inflammation; it may result in cell death

dermatitis: Inflammation of the skin: contact dermatitis is due to local exposure and may be caused by irritation, allergy or infection

descriptive epidemiology: Study of the occurrence of disease or other health-related characteristics in populations, including general observations concerning the relationship of disease to basic characteristics such as age, sex, race, occupation, and social class; it may also be concerned with geographic location. The major characteristics in descriptive epidemiology can be classified under the headings: individuals, time and place
IPCS, 1978

desensitization: Suppression of sensitivity of an organism to an allergen to which the organism has been exposed previously

desiccant:

1. Drying agent
2. In agriculture, a substance used for drying up plants and facilitating their mechanical harvesting.

desorption: Opposite of adsorption; a decrease in the amount of adsorbed substance
Gold, Loening, McNaught and Sehmi, 1987

desquamation: Shedding of an outer layer of skin in scales or shreds

detoxification:

1. Process, or processes, of chemical modification which make a toxic molecule less toxic
2. Treatment of patients suffering from poisoning in such a way as to promote physiological processes which reduce the probability or severity of harmful effects

detoxification by haemosorption perfusion: Passage of a patient's blood through a set of columns filled with a haemosorbent (activated charcoal, ion-exchange resin, etc.): the purpose of the operation is to remove a toxic substance from the organism, particularly in an emergency
RT haemoperfusion, haemosorption.

detriment: Estimated measure of the expected harm or loss associated with an adverse event, usually in a manner chosen to facilitate meaningful addition over different events. It is generally the integrated product of arbitrary values of risk and hazard and is often expressed in terms such as costs in US dollars, loss in expected years of life or loss in productivity, and is needed for numerical exercises such as cost-benefit analysis.

developmental toxicity: Adverse effects on the developing organism (including structural abnormality, altered growth, or functional deficiency or death) resulting from exposure prior to conception (in either parent), during prenatal development, or postnatally up to the time of sexual maturation.
IRIS, 1986
RT embryotoxicity, teratogenicity

diaphoresis: Profuse perspiration

diaphoretic: Causing profuse perspiration
SN sudorific

2,3-dimercaptopropan-1-ol: Metal chelator which has been used in the treatment of arsenic, antimony, gold, mercury and lead poisoning
SN British anti-Lewisite, dimercaprol

dimercaprol: See SN 2,3-dimercaptopropan-1-ol

diploid: Chromosome state in which the chromosomes are present in homologous pairs. Normal human somatic (non-reproductive) cells are diploid (they have 46 chromosomes), whereas reproductive cells, with 23 chromosomes, are haploid
RT haploid, meiosis, mitosis

discharge: See SN emission

discharge (effluent, emission) standard or release limit: Maximum amount of a pollutant released from a given source to a specified medium which is acceptable under specified circumstances
WHO, 1979

discordance (genetic): Any difference in a character between individuals due to genetic differences such as may occur in dizygotic twins, or between matched pairs in a case cohort study
AN concordance

disease: Literally, dis-ease, lack of ease; pathological condition that presents a group of symptoms peculiar to it and which establishes the condition as an abnormal entity different from other normal or pathological body states

discontinuous effect: See SN intermittent effect

disposition: Natural tendency shown by an individual or group of individuals, including any tendency to acquisition of specific diseases, often due to hereditary factors

dissipation: Reduction in the amount of a pesticide or other compound which has been applied to plants, soil etc. (used when it is not clear whether this is by mineralization degradation, binding, or leaching)

distributed source: See SN area source
RT point source

distribution:

1. Dispersal of a substance and its derivatives throughout the natural environment.
2. Dispersal of a substance within an organism, including metabolism, storage and excretion.
3. Final location of a substance within an organism after dispersal.

diuresis: Excretion of urine, especially in excess

diuretic: Agent which increases urine production
SN micturitic

dosage: Dose expressed as a function of the organism being dosed and time, for example mg/(kg body weight)/day
See dose

dose: Total amount of a substance administered to, taken or absorbed by an organism
NT absolute lethal dose,
cumulative median lethal dose,
lethal dose,
maximum tolerable dose,
maximum tolerated dose,
median effective dose,
median lethal dose,
median narcotic dose,
minimum lethal dose,
non-effective dose,
organ dose,
threshold dose,
toxic dose

dose-effect curve: Graph of the relation between dose and the magnitude of the biological change produced measured in appropriate units
RT concentration-effect curve

dose-effect relationship: Association between dose and the magnitude of a continuously graded effect, either in an individual or in a population or in experimental animals
RT concentration-effect relationship

dose-related effect: Situation in which the magnitude of a biological change is related to the dose
AN non-dose-related effect

dose-response curve: Graph of the relation between dose and the proportion of individuals in a population responding with an all-or-none effect
RT concentration-response curve,
response

dose-response relationship: Association between dose and the incidence of a defined biological effect in an exposed population
RT concentration-response relationship,
response

Draize test: Evaluation of materials for their potential to cause dermal or ocular irritation and corrosion following local exposure; generally using the rabbit model (almost exclusively the New Zealand White) although other animal species have been used

drug: Any substance which when absorbed into a living organism may modify one or more of its functions. The term is generally accepted for a substance taken for a therapeutic purpose, but is also commonly used for abused substances
SN medicine, pharmaceutical
After WHO, 1978a

duplicate portion sampling method (diet/food): Method frequently used for the same purposes as the total diet study technique. Test persons consume their ordinary diet but for each meal, they prepare for subsequent analysis a duplicate portion of all food as prepared, served and consumed
SN duplicate diet study

duplicate (replicate) samples (in chemistry): Two (or multiple) samples taken under the same or comparable conditions
PAC, 1990

dysarthria: Imperfect articulation of speech due to neuromuscular damage

dysfunction: Abnormal, impaired, or incomplete functioning of an organism, organ, tissue or cell

dysplasia: Abnormal development of an organ or tissue identified by morphological examination

dyspnoea: Difficult or laboured breathing