Effects on Biological Systems

The acute toxicity of all the chlorinated aromatics to mammals is low, with rat LD50 values ranging from 500 mg/kg for the dichlorobenzenes, to 10 g/kg and higher for some grades of Arochlor. Many are absorbed through the skin, but do not produce acute systemic effects by this route, except at high concentrations. 

Human fatal poisoning incidents have been recorded, particularly for PCB (the Yusho incident, [59]), PCN [81] and hexachlorobenzene [80, 134]. The effects of poisoning are chloracne, hepatic porphyria, liver damage, blood disorders and, at lower concentrations, disorders of the nervous system. 

Many of these symptoms have been reproduced in chronic laboratory feeding trials, but only at comparatively high concentrations, of at least 100 mg/kg, rising to 1,000 mg/kg and higher in the diet [17, 115, 134]. 

Mink and Rhesus monkeys have been shown to be particularly sensitive to PCB, with marked loss of growth, and particularly reproductive failure, at dietary levels as low as 3 mg/kg [77, 93]. 

Helle [58] reports a correlation between high residue levels in seals and reproductive impairment, caused by uterine abnormalities but although the blubber of non-pregnant females contained 100 mg/kg PCB, it also contained a similar quantity of DDT. 

---

Although there are several definitions of biocompatibility, the concept named as biocompatibility is usually used to describe the ability of a material to perform a desired function without producing a negative effect on biological systems in specific... 

It may be of value to differentiate the indicating and monitoring uses of plants. Most reported work has used the indicator concept, with plant injury (symptoms) as indicative of a problem. Monitoring implies some degree of reliability. Several studies have attempted to use plant response as a monitor of pollution concentrations or doses, with variable but uncertain success. Plants could also be considered monitors if th gave a reliable index of the biologic effects on biologic systems of concern to man (crops, forests, animals, and man himself). The latter has not been seriously discussed. 

An important aspect of metal-microbe interactions, but one that is rarely addressed, is metal speciation and metal bioavailability. It is the metal species present and their relative bioavailability rather than total metal concentration in the environment that determines the overall physiological and toxic effects on biological systems (Bernhard, Brinckman Sadler, 1986 Hughes Poole, 1989 Morrison, Batley Florence, 1989). 

Two very actual applications of respirometric test were performed on radon pollution and cellular phone field effect on biological system, both of great actuality and object of controversies due to contrasting conclusions reached by different authors, very often basing on unclear and poorly accurate measurements. Particularly for cellular phone field, it was concluded that 900 and 1800 MHz, corresponding to cellular... 

Adey, W. R. Long-range electromagnetic field interactions at brain cell surfaces. In "Magnetic Field Effect on Biological Systems" T. Tenforde, Ed. Plenum Press New York, 1979 pp. 57-78. 

Toxicology The multidisciplinary study of toxicants, their harmful effects on biological systems, and the conditions under which these harmful effects occur. The mechanisms of action, detection, and treatment of the conditions produced by toxicants are studied. 

Environmentally induced deteriorations. Currently most emphasis in studies of environmental effects on biological systems is on toxicity and the onset of malignancy. Malignancy is usually directly associated with nucleic acids, but, at least in some cases, nuclear and other proteins may be involved as well. This is an area requiring intensive research. Toxicities usually involve the interaction of the toxic agents with some protein system, particularly enzyme systems. 

These are the reasons of the difficulty to distinguish the effects on biological systems attributed to normal pollution (primary) and those due to chemical reactions in the atmosphere (secondary pollution). 

Actidione and Anisomycin. These two anti-fungal antibiotics were tested, not because they were antibiotics, but because of their known inhibitory effects on biological systems such as those involved in protein synthesis. Both were found to be active 21) but were never pursued beyond the initial screening stages because of high cost and particularly their animal toxicity, especially to the mucosa. 

Solubilizers (e.g., organic solvents, detergents, Pluronics) are often used to solubilize drugs in aqueous solution without considering their effects on biological systems, such as (i) lipid membranes and (n) multidrug resistance (MDR) efflux transporters (e.g., Pgp or MDRl). 

Hoover, D.G. Pressure effects on biological systems. Food Technol., 47, 150, 1993. 

Drost-Hansen, W. (1%5). The effects on biologic systems of higher-order phase transitions in water. Ann. N.Y. Acad. Sci. 125,471-501. 

Drost-Hansen, W. (1981). Gradient device for the study of temperature effects on biological systems. J. Wash. Acad. Sci. 71, 187-201. 

VisekWJ. 1984. Ammonia Its effects on biological systems, metabolic hormones, and reproduction. J Dairy Sci 67(3) 481-498. 

All these compounds are more similar to benzene in stability and chemical behavior than they are to the alkenes. Many of these compounds are components of molecules that have significant effects on biological systems. For instance, the purines and pyrimidines are components of DNA (deoxyribonucleic acid) and RNA (ribonucleic acid). DNA and RNA are the molecules responsible for storing and expressing the genetic information of an organism. The pyridine ring is found in... 

We sincerely hope that the scattered environmental geochemical information may be combined in the future to broaden the knowledge about the routes of transfer of each constituent, either from natural sources or emitted by human activity and the ultimate effect on biological systems. In publishing these results, a start in this direction has been made which may eventually lead to a fertilization in this line of thought. 

---