Environmental factor or ecological factor or ecofactor is any factor, abiotic or biotic, that influences living organisms. Abiotic factors include ambient temperature, amount of sunlight, and pH of the water soil in which an organism lives. Biotic factors would include the availability of food organisms and the presence of conspecifics, competitors, predators, and parasites.
An organism's genotype (e.g., in the zygote) is translated into the adult phenotype through development during an organism's ontogeny, and subject to influences by many environmental effects. In this context, a phenotype (or phenotypic trait) can be viewed as any definable and measurable characteristic of an organism, such as its body mass or skin color.
Apart from the true monogenic genetic disorders, environmental factors may determine the development of disease in those genetically predisposed to a particular condition. Stress, physical and mental abuse, diet, exposure to toxins, pathogens, radiation and chemicals found in almost all personal-care products and household cleaners are common environmental factors that determine a large segment of non-hereditary disease.