Oxidative and Conjugative Metabolism of Xenobiotics by Livers of Cattle, Sheep, Swine and Rats1

Smith, G. S.; Watkins, John B.; Thompson, Thomas N.; Rozman, K.; Klaassen, Curtis D.

doi:10.2527/jas1984.582386x

Cited by 65 publications

(25 citation statements)

References 35 publications

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“…1998). This may be, in part, a function of differences in the activity of liver enzymes involved in the degradation of EDCs; for example, there are differences between ruminants, pigs and rodents in this factor (Smith et al. 1984; Watkins and Klaassen 1986).…”

Section: An Insidious and Significant Threat – A Considered View?mentioning

confidence: 99%

Are Endocrine Disrupting Compounds a Threat to Farm Animal Health, Welfare and Productivity?

Rhind¹

2005

Reprod Domestic Animals

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Contents The sources and characteristics of endocrine disrupting compounds (EDCs) are reviewed and discussed with respect to their potential effects on farm animal health, welfare and productivity. The importance of certain properties of these compounds in relation to the expression of their biological effects is addressed together with potential routes of exposure. It is concluded that little is known of factors affecting the tissue concentrations of EDCs in farm animals, the concentrations that are required to perturb physiological function in these species, the effects of prolonged exposure to low doses, the effect of cocktails of EDCs and other pollutants or the responses of specific organs and physiological systems that are affected by EDCs. Much of the available information pertaining to EDCs is derived from epidemiological studies of wildlife species and from laboratory animal studies and while these studies have significant limitations, they are considered to be valuable indicators of potential effects in farm animal species. The results of such studies, together with the small amounts of data from studies of ruminants, indicate that there may be significant effects of exposure to environmental levels of EDCs on farm animal health, even although effects are not generally apparent in practice, at this time.

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Section: An Insidious and Significant Threat – A Considered View?mentioning

confidence: 99%

Are Endocrine Disrupting Compounds a Threat to Farm Animal Health, Welfare and Productivity?

Rhind¹

2005

Reprod Domestic Animals

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“…Αυτό αντανακλά στις διαφορές των ειδών στο μετα βολισμό του ήπατος και ιδιαίτερα στις επιπτώσεις εξω γενών ή ενδογενών στεροειδών ουσιών στην ηπατική λειτουργία (Colby, 1980). Στα μηρυκαστικά, οι επι δράσεις των μικροβιακών πληθυσμών της μεγάλης κοι λίας στην αποικοδόμηση των EDCs και στην απορρό φηση τους μπορεί να είναι περισσότερο σημαντικές από τους βιομετασχηματισμοΰς στο ήπαρ (Smith et al, 1984).…”

Section: ε) απορρόφηση μεταβολισμός και συσσώρευσηunclassified

Environmental toxic Endocrine Disrupting Compounds (EDCs): Effects on environment, animal production and human

Dosis¹,

Καμαριανοσ)²

2017

J Hellenic Vet Med Soc

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Endocrine disrupting compounds (EDCs) encompass a variety of chemical classes, including several different categories of substances. Some are natural, such as plant oestrogens and mycoestrogens, while most are chemically composed. Residues are found in water, in sewage sludge, in the atmosphere and in foodstuff of vegitative or animal origin. The most common compounds include organochlorine pesticides, alkyl phenols, pthalates, polychlorinated biphenyls (PCBs), dioxins and polybrominated diphenyl ethers (PBDEs). Their properties render some as ubiquitous and persistent in the environment, they can be transported long distances and have been found in virtually all regions of the world. Their sources can vary from direct, such as effluents from wastewater, sewage, industrial sludge processes or agricultural effluents, to indirect, such as filtering agricultural soils, transportation through rain or air from civil and industrial centers to rivers and the surrounding environment. Others are rapidly degraded in the environment or human body or may be present for only short periods of time, but at critical periods of development. Although in low concentrations, the continuous exposure of animals of many species, including humans, induces adverse effects, such as disruption of reproductive function and of the immune system, as well as carcinogenic effects. The effects are obvious in wildlife, especially fish, and laboratory experiments. Sex change (feminizing) in fish has been observed, sexual differentiation in rats, egg shelling thinning, thyroid function disruption and mental and physical function disruption in wildlife. Most important and common is the disruption in the reproductive and the immune system of animals. As far as humans are concerned, reduction in sperm count and sperm quality has been heavily linked with EDC exposure, and furthermore, suspicions arise linking several cancer incident increments, such as testicular cancer, to EDC exposure. Still, although it is clear that many environmental chemicals can interfere with normal hormonal processes, there is weak evidence that human health can be adversely and directly affected by exposure to endocrine active chemicals. However, there is sufficient evidence to conclude that adverse endocrine mediated effects have occurred in wildlife species and laboratory studies exist to support these conclusions. The routes of exposure are numerous. Food is a common route of exposure, especially in younger animals that consume food containing higher fat percentages (e.g. milk). Soil is another route of exposure. Thus grazing animals tend to have a higher risk factor, due to surface soil pollution with EDCs. A vegetative nutrition with EDC residues is another high risk factor for these animals. On the other hand, animals bred with forage tend to be at lower risk factor, given that food is tested for low levels of EDCs. Water intake is not considered a significant route of exposure. EDCs possess the ability to act as either hormone agonists or antagonists or disrupt hormone synthesis, storage or metabolism. Due to their persistence in the environment, they are concentrated in fat tissue and are released when the fat is mobilized duringpregnancy or lactation, thus exposing embryos and neonates, which are very susceptible at this stage of development, to high concentrations of EDCs. The concerns that arise regarding the exposure to these EDCs are due primarily to:- these adverse effects observed in certain wildlife, fish and ecosystems- the increased incidences of certain endocrine-related human diseases and- endocrine disruption resulting from exposure to certain environmental chemicals observed in laboratory experimental animals.

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“…Early comparative metabolic studies on the rate of biotransformation of model substrates in liver microsomes show that there may be important differences in metabolic rates of alkoxyresorufins between sheep and cattle. Smith et al (1984) found that hepatic EROD in cattle (n=5) was 14 fold higher than in sheep (n=5). This difference was confirmed in a study carried out in cultured hepatocytes isolated from sheep (n=3) and cattle (n=4) showing a 3-fold greater EROD activity in cattle cells (Van t' Klooster et al, 1993).…”

Section: Comparative Expression and Activity Of Cyp1 Enzymes In Sheepmentioning

confidence: 99%

Scientific Opinion on the risk to public health related to the presence of high levels of dioxins and dioxin‐like PCBs in liver from sheep and deer

2011

EFS2

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EFSA was asked by the European Commission to deliver a scientific opinion on the risk to public health related to the presence of high levels of dioxins and dioxin-like PCBs in liver from sheep and deer. The opinion should also explore possible reasons for these high findings. Moreover, EFSA was asked whether dioxin and polychlorinated biphenyl (PCB) levels for liver should better be expressed on fresh weight rather than on a fat basis. The Panel on Contaminants in the Food Chain (CONTAM Panel) evaluated dioxin and PCB results from 332 sheep liver, 175 sheep meat and 9 deer liver samples submitted by eight European countries and estimated the exposure through consumption of sheep liver for adults (consumers only) and children. Regular consumption of sheep liver would result on average in an approximate 20 % increase of the median background exposure to dioxins and dioxin-like PCBs (DL-PCBs) for adults. On individual occasions, consumption of sheep liver could result in high intakes exceeding the tolerable weekly intake (TWI). The CONTAM Panel concluded that the frequent consumption of sheep liver, particularly by women of child-bearing age and children, may be a potential health concern. Additional intake of non dioxin-like PCBs (NDL-PCBs) from consumption of sheep liver does not add substantially to the total dietary intake. The range of fat content in sheep liver is considerably narrower than for a number of other food categories regulated in Regulation (EC) No 1881/2006. Therefore, the CONTAM Panel sees no need to change the basis for expression of results and maximum levels solely for liver from fat weight to fresh weight basis. A lower activity of CYP1A enzymes in sheep than in cattle was identified as a possible reason for higher dioxin and DL-PCB levels in sheep liver. Dioxins and dioxin-like PCBs in liver from sheep and deer EFSA Journal 2011;9(7):2297 2 © European Food SUMMARYFollowing a request from the European Commission, the Panel on Contaminants in the Food Chain (CONTAM Panel) was asked to deliver a scientific opinion on the risk to public health related to the presence of high levels of dioxins and dioxin-like polychlorinated biphenyls (PCBs) in liver from sheep and deer. The opinion should also explore possible reasons for the findings of high levels of dioxins and PCBs in liver from sheep and deer. Finally, the question was raised whether dioxin and PCB levels for liver, as for fish, should better be expressed on a fresh weight basis rather than on a fat basis.Polychlorinated dibenzo-p-dioxins (PCDDs) and dibenzofurans (PCDFs) are two groups of tricyclic planar compounds that often are together referred to as "dioxins". Unless otherwise stated, in this opinion the term "dioxins" refers to PCDDs and PCDFs together. Dependent on the number of chlorine atoms (1-8) and their positions in the rings, 75 PCDDs and 135 PCDFs, termed "congeners", can occur. Dioxins are poorly soluble in water but highly soluble in lipids. Due to their lipophilic properties they accumulate in the food chain and a...

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Oxidative and Conjugative Metabolism of Xenobiotics by Livers of Cattle, Sheep, Swine and Rats1

Cited by 65 publications

References 35 publications

Are Endocrine Disrupting Compounds a Threat to Farm Animal Health, Welfare and Productivity?

Are Endocrine Disrupting Compounds a Threat to Farm Animal Health, Welfare and Productivity?

Environmental toxic Endocrine Disrupting Compounds (EDCs): Effects on environment, animal production and human

Scientific Opinion on the risk to public health related to the presence of high levels of dioxins and dioxin‐like PCBs in liver from sheep and deer

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