systems, changes in the development of the fetus, decreased ability to reproduce and suppressed immune system. Impact on human health Shortterm exposure of humans to high levels of dioxins may result in skin lesions, such as chloracne and patchy darkening of the skin, and altered liver function. Longterm exposure is linked to impairment of the immune system, the developing nervous system, the endocrine system and reproductive functions. Due to the omnipresence of dioxins, all people have background exposure and a certain level of dioxins in the body, leading to the socalled body burden. Current normal background exposure is not expected to affect human health on average. However, due to the high toxic potential of this class of compounds, efforts need to be undertaken to reduce current background exposure. Sensitive subgroups The developing fetus is most sensitive to dioxin exposure. The newborn, with rapidly developing
Among other studies, they counted the frequency of words to attempt a chronology for the chapters of the Koran, certain words being considered as having been used only in the later chapters. Lexicography advanced this. In making a dictionary, considerations of letter-frequency and of which letters go or do not go together virtually thrust themselves upon the lexicographer. For example, the Arabs recognized early that za' was the rarest letter in Arabic and, contrariwise, that the omnipresence of the definite article "al- " made alif and lam the most common letters in normal style. The Ibn ad-Duraihim—Qalqashandi exposition begins at the beginning: the cryptanalyst must know the language in which the cryptogram is written. Because Arabic, "the noblest and most exalted of all languages," is "the one most frequently resorted to" (in that part of the world), there follows an extensive discussion of its linguistic characteristics
annaabi.ee 
