Food, particularly dairy products, meat, and fish, has been identified as the primary immediate source of intake of polychlorinated dibenzo-p-dioxins (PCDDs), polychlorinated dibenzofurans (PCDFs), and polychlorinated biphenyls (PCBs) for the general population. We previously reported PCDD/Fs in individual analyses of food samples from a number of countries, including the U.S., the former Soviet Union, and Vietnam. We also previously estimated daily intake of dioxins and related chemicals in Americans at various ages in these reports. In this paper, the levels of dioxins, dibenzofurans, dioxin toxic equivalents (TEQs), selected dioxin-like PCBs, and DDE (a persistent metabolite of DDT) were measured in 12 pooled food samples from over 90 individual specimens collected from supermarkets throughout the United States during 1995. Samples were pooled by food groups and then analyzed. Food samples were collected in Binghamton, New York; Atlanta, Georgia; Chicago, Illinois; San Diego, California; and Louisville, Kentucky. In addition to the meat, dairy, and fish samples, a vegan (all vegetable, fruit and grain, no animal product) diet, was simulated; this showed the lowest level of dioxins.

Benzofurans↗

PubMedDate not supplied

A comparison of critical osmolality and hydraulic conductivity and its activation energy in fowl and bull spermatozoa.

Measurements were made of critical osmolality, the osmolality at which 50% of the cells are lysed, and of the permeation time, the time taken to lyse 50% of the cells in an osmotic solution lower than the critical osmolality, for fowl and bull spermatozoa. Cell lysis was determined by means of fluorescent viability stains (carboxyfluorescein diacetate and propidium iodide) using a flow cytometer. The advantages and pitfalls of this approach are addressed. The values obtained have been used to compute the water permeability, or hydraulic conductivity, of the plasma membrane and its activation energy for each species. Fowl spermatozoa were found to have a lower critical osmolality (17 mOsm) than bull spermatozoa (36 mOsm), and this is discussed in relation to the differences in cell shape and size. The hydraulic conductivities of fowl and bull spermatozoa were 2.1 and 10.8 microns x atmosphere x minute, respectively, and the respective activation energies were 4.4 and 3.0 kcal/mol. The relevance of these findings to cryopreservation of spermatozoa is considered.

Animals↗