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At least 1,171 records · Page 65Linked to original sources

PubMed2000

The reproductive strategy of Leporinus friderici (Characiformes, Anostomidae) in the Paraná River basin: the effect of reservoirs.

The reproductive strategy of a species depends upon the interaction between intrinsic and extrinsic factors. Examining the population of Leporinus friderici in two reservoirs of the Upper Paraná River basin in reference to first gonadal maturation and breeding season and sites, the present investigation tested whether the environment formed by damming promoted spatial and temporal changes in the reproductive strategy of this species. Analyses of sex ratios showed that females significantly predominated in Itaipu, while in Corumbá the sexes were about equal with a slight predominance of males. Size-associated sexual dimorphism was observed, that is females dominated the longer length categories, and males the shorter. The minimum size at which L. friderici initiated reproduction varied from year to year, and was larger in the periods soon after formation of both reservoirs. In Itaipu, stabilization between the maximum and minimum lengths at first maturation was also noted after year 6 following closure and continuing until year 15. In general, the breeding season lasted from October through April, although cyclic changes in the duration and intensity of this season were evident. Young individuals predominated during the entire study period in Corumbá. The formation of Itaipu Reservoir had a greater effect on the reproduction of L. friderici, where a gradual adaptation of the reproductive strategy of this species may possibly have been occurring. It is also possible that some of the characteristics of the Itaipu population will in the future be shown by the Corumbá population. It was concluded that reproductive strategies constitute ecological adaptations that are temporally and spatially altered and are fitted to resource availability and environmental pressure.

Journal Article↗

PubMedDate not supplied

Histological characteristics of placentas from assisted reproduction programs.

Placentas from assisted reproduction programs are a poorly investigated research material. The aim of this investigation was to perform microscopic examination of placentas from assisted reproduction programs and to compare them with placentas from spontaneous pregnancies. The investigation comprised 12 placentas from assisted reproduction programs and 12 placentas from spontaneous pregnancies. We found a statistically significant increase of villous edema in investigated placentas (p = 0.001). We also found a statistically significantly increased incidence of microcalcifications in placentas from assisted reproduction programs (p = 0.04). There was no statistically significant difference between the two groups in regard to syncytial knots (X2 = 0.67, p > 0.25). Microscopic examination showed that placentas from assisted reproduction programs present with more frequent pathological findings. Further investigations of placentas from assisted reproduction programs could provide better understanding of different pathological conditions of pregnancies and labor in women with artificial insemination.

Female↗

PubMed2000

Carboxylesterases moonlight in the male reproductive tract: a functional shift pivotal for male fertility.

This essay addresses the carboxylesterase redundancy in the male reproductive tract seemingly conserved across phyla. Evidence is provided which suggests that carboxylesterases are recruited by the male reproductive system in certain animal groups. These provide advantageous metabolic capabilities to sperm protection, sperm maturation, and sperm use. Rather than an archival record of the available data, we seek possible answers to the central question: Why is carboxylesterase over-expression adaptive with the functioning of the male reproductive tract with respect to male fertility? We discuss patterns of carboxylesterase over-expression and accumulation in different compartments of the male reproductive tract. We also provide evidence of how these patterns are associated with a long sperm path to egg through different local effects. The hyper-expression of carboxylesterases can play different physiological roles depending on its localization in the male reproductive system. However, all the "acquired" functions can serve the same purpose; creating conditions which maximize the fertilizing potential of the sperm. To confirm our concept and more clearly illuminate "moonlighting" roles of carboxylesterases in the male reproductive tract, requires a more extensive comparative analysis of a variety of carboxylesterases in a larger number of species.

Carboxylesterase↗

PubMed1987

Dairy herd reproductive management programs with or without synchronization of estrus.

Reproductive efficiencies were compared among herds with (treated, n = 25) or without (visited control, n = 25) routine synchronization of estrus and herds without investigator visits (unvisited control, n = 22). Treatment groups were subdivided based on participation in veterinary herd health programs. Reproductive tracts were palpated rectally at 21-d intervals for 6 mo in two sets of treated and visited control herds. Data were collected during the visitation period and from the 6-mo period before visits. In treated herds, cows more than 40 d postpartum with a corpus luteum received prostaglandin F2 alpha. In visited control herds, cows received prostaglandin F2 alpha after 82 d postpartum if they were not observed in estrus. Routine synchronization of estrus did not enhance herd reproductive efficiency compared with no synchronization of estrus in visited herds. Small changes in reproductive efficiency occurred during visits in herds with an established reproductive health program. However, herds not using a health program had 15.2 fewer d from calving to insemination, and the pregnancy rate at 120 d postpartum was 13.0 percentage units higher than before herd visits. Consequently, reproductive performance of those herds during visits was similar to that of contemporaries under a herd health program.

Animal Husbandry↗

PubMed1988

Reproductive disorders in the periparturient dairy cow.

Incidence, predisposing factors, and implications of various reproductive disorders (dystocia, twinning, stillbirth, retained placenta, cystic ovaries, anovulation, infections of the reproductive tract, metritis, and abnormal health status) are reviewed as to their inter-relationships and collective impact on reproductive performance, milk yield and predisposition to other diseases or disorders in the periparturient dairy cow. All reproductive disorders reviewed reviewed reduce reproductive performance either directly or indirectly. Concurrent milk yield was reduced marginally in a few studies as a consequence of twinning, retained placenta, cystic ovaries, metritis, or other uterine disorders, and in cows with an abnormal health status. There is strong evidence for associated losses in milk yield following surgical delivery of a stillborn calf. We conclude that most periparturient disorders occur as a complex, rather than as a single abnormality. Cows with one disorders are at increased risk for other disorders, including metabolic ones. In contrast, actual milk yield or potential for high production generally does not predispose cows to increased risk for any of the reproductive disorders. The literature suggests that prophylactic measures to prevent occurrence of the one disorder might decrease the risk and incidence of other related disorders, either directly or indirectly.

Animals↗

PubMed1999

The use of reproductive health information material in the rural clinics of Umtata district.

Though it appears that there has been a long history of development, distribution and dissemination of reproductive health information materials, impediments still exist in the health information, communication and education systems in South Africa. The aim of the study was to contribute towards improvement of the development, distribution and utility of reproductive health information material both in the Eastern Cape province and nationally. In-depth understanding of complexities surrounding development, distribution and utility of educational material is key to the provision of information to communities. The objectives were to describe the availability and examine the content, target groups, language and utility of reproductive health information materials. Qualitative study using non probability sampling was done. Ten rural clinics were conveniently selected. In-depth interviews, focus groups and a checklist were used to collect data. Reproductive health information materials found were mostly posters, there were no pamphlets, material on some reproductive health aspects was not available, inconsistently distributed and not updated. It was concluded that posters are available in the rural clinics of Umtata district judging from the results there is a need to improve the quality of reproductive health information material.

Ambulatory Care Facilities↗

PubMed2002

Endogenous retrovirus sequences expressed in male mammalian reproductive tissues: a review.

OBJECTIVES: To review the research findings on the expression of endogenous retroviruses and retroviral-related particles in male mammalian reproductive tissues, and to discuss their possible role in normal cellular events and association with disease conditions in male reproductive tissues. DATA SOURCES: Published findings on endogenous retrovirus (ERV) expression in vertebrate reproductive tissues. STUDY SELECTION: Relevant citations on ERVs and male reproduction by research groups worldwide. DATA EXTRACTION: Literature search on Medline and Pubmed upto the year 2000, and retrieval of relevant articles cited from international and local journals. DATA SYNTHESIS: Most of the studies demonstrated integrated retroviruses and retroviral-related sequences in human and mouse testis, epididymis and vas deferens. Endogenous retroviruses in human and mice may be associated with normal cellular differentiation and development, and carcinogenesis. In humans, one ERV family, human endogenous retrovirus-K (HERV-K) is abundantly expressed, and is associated with germ cell tumours, while ERV3 env is expressed in normal human testis. CONCLUSION: The expression of ERVs in male reproductive tissues suggests a possible role in normal and disease conditions involving the testis and epididymis. These speculative functions may include among others spermatogenesis and or sperm maturation or tumour formation. However, further studies need to be carried out to investigate specific roles of ERVs in male reproductive events.

Animals↗

PubMed1983

Methods for detecting occupational causes of male infertility. Reproductive history versus semen analysis.

The use of semen and reproductive histories in epidemiologic studies is reviewed. Traditional parameters of semen quality are easily measured. A significant change may be positive proof of an effect on the reproductive tract and may occur within two or three months of the start of exposure. Conversely, semen specimens are difficult to obtain. The use of an appropriate reference group may be hard to ensure. A change in semen quality need not lead to abnormalities of reproduction. Past effects of exposure may not be detectable if exposure has been reduced or eliminated. Reproductive histories are readily obtained for fertility analysis. A reduction in fertility may be evidence of impaired health. Past effects of exposure are easily determined. For the detection of reduced fertility, however, two or three years of exposure may be needed. A change in fertility does not necessarily indicate an effect on the reproductive tract. The analysis of fertility requires considerable technical expertise. Since data for fertility analysis may be gathered in the workplace with little effort, suitable information should be obtained during employee medical examinations wherever potential exists for effects on reproduction.

Epidemiologic Methods↗

PubMed2006

Men in Australia Telephone Survey (MATeS): predictors of men's help-seeking behaviour for reproductive health disorders.

OBJECTIVE: To identify sociodemographic factors associated with help-seeking behaviour for reproductive health disorders in middle-aged and older Australian men. DESIGN: A cross-sectional, population-based, computer-assisted telephone interview exploring sociodemographic factors and general and reproductive health. PARTICIPANTS AND SETTING: Analysis of data from the Men in Australia Telephone Survey (MATeS) of 5990 Australian men aged 40 years and older interviewed between September and December 2003. MAIN OUTCOME MEASURES: Self-reported diagnosis of prostate disease and erectile dysfunction (ED), help-seeking behaviour (including visiting a doctor, prostate-specific antigen testing, treatment of prostate disease, speaking to a health professional about ED and treatment of ED). RESULTS: Age was a significant predictor of all help-seeking behaviour studied, other than treatment for ED. Controlling for all predictor variables, never-married status predicted a lower likelihood of visiting a doctor (odds ratio [OR], 0.68 [95% CI, 0.48-0.97]) or speaking to a health professional about ED (OR, 0.44 [95% CI, 0.21-0.93]), while divorced/separated status predicted lower likelihood of having a prostate-specific antigen test (OR, 0.63 [95% CI, 0.50-0.79]). Living in a regional or remote area or being from a non-English-speaking background predicted lower likelihood of receiving treatment for ED (ORs, 0.62 [95% CI, 0.42-0.92] and 0.41 [95% CI, 0.24-0.72], respectively), but did not influence screening for prostate disease. CONCLUSION: Seeking advice or treatment for male reproductive health disorders is predicted by sociodemographic factors specific to different reproductive health problems. As middle-aged and older men do attend doctors, opportunities exist for health professionals to optimise their consultations by routinely discussing reproductive health with all men, to identify under-reported male reproductive health disorders.

Adult↗

PubMed2000

Carbon and nitrogen allocation to male and female reproduction in Rocky Mountain Douglas-fir (Pseudotsuga menziesii var. glauca, Pinaceae).

We measured carbon (respiration, photosynthesis, and production) and nitrogen allocation to male and female cones of Rocky Mountain Douglas-fir (Pseudotsuga menziesii var. glauca) to quantify gender-specific: (1) resource allocation to reproduction, and (2) contribution to carbon costs of reproduction via photosynthesis. We also measured foliar photosynthesis and nitrogen concentration ([N]) near and far from female cones to examine the relationship between reproduction and foliar physiology. Over one growing season, male cones required only 8% of all carbon allocated to reproduction, with females consuming the remaining 92%. Female cones, however, had maximum instantaneous refixation rates of 54%, which, integrated over the season, offset 6% of their total carbon requirements, while male cones were completely dependent on vegetative tissues for carbon. Male cones received 22% of all nitrogen allocated to reproduction and female cones received the remaining 78%. Foliage near female cones had elevated photosynthesis during the early stages of cone development and consistently lower [N] than foliage far from cones. Although female cones may photosynthesize, the annual sum of carbon fixed by reproductive structures is minor in comparison to the total carbon allocated to production and respiration.

Journal Article↗

PubMedDate not supplied

Atrazine effects on testosterone levels and androgen-dependent reproductive organs in peripubertal male rats.

Previous studies have reported that atrazine, a widely used herbicide that selectively inhibits photosynthesis in broadleaf and grassy weeds, has adverse effects on reproductive function in the male, suggesting a direct effect of atrazine on the hypothalamicpituitary-testicular axis. As yet, however, no studies have critically examined the doses of atrazine that elicit such effects, and few have focused on the mechanism by which atrazine acts. Herein we report a dose-response study of the effects of atrazine ingestion on reproductive function in male Sprague-Dawley rats during a critical developmental period, the peripubertal period. Atrazine was administered by gavage to rats from day 22 to day 47 of age, at doses of 1-200 mg/kg body weight per day. Atrazine administration of up to 50 mg/kg per day had no effect on any of the measured variables. Serum testosterone concentration was reduced by atrazine at doses of 100 and 200 mg/kg per day, as were seminal vesicle and ventral prostate weights. Intratesticular testosterone concentration was reduced in parallel with serum testosterone, suggesting that the reductions in serum testosterone resulted from reduced testosterone production by Leydig cells or from changes in testosterone metabolism within the testis, or both. Serum luteinizing hormone (LH) concentration was reduced despite the reduced serum testosterone, suggesting an effect on the hypothalamus, the pituitary gland, or both. At the termination of the study, the average body weight of rats receiving atrazine at 100 mg/kg per day was found to be reduced by approximately 9%. This suggested the possibility that the effects of atrazine on the reproductive tract may not be direct, but rather, the noted deficits of the male reproductive tract resulted from reduced food intake by the treated rats. We tested this by feeding control (vehicle-gavaged) rats amounts of food equivalent to that consumed by the atrazine-fed rats, and then assessing reproductive tract endpoints. Even mild food restriction resulted in reductions in serum testosterone concentration, in the weights of androgen-dependent organs, and in serum LH concentration; the same deficits that were seen in atrazine-gavaged rats. Indeed, the effects of atrazine on the male reproductive tract seen in rats receiving atrazine at greater than 50 mg/kg per day could not be distinguished from the effects of reduced food consumption. These results suggest that caution must be exercised before concluding that atrazine (or any potentially toxic chemical) has direct, detrimental effects.

Age Factors↗

PubMed2001

Where are we on teen sex?: Delivery of reproductive health services to adolescents by family physicians.

BACKGROUND AND OBJECTIVES: This study describes variation in reproductive health preventive services delivery to adolescents by family physicians in Upstate New York. METHODS: We surveyed a stratified random sample of 354 family physicians from three New York State metropolitan statistical areas about the proportion of their adolescent patients (ages 15-18) to whom they deliver preventive reproductive health interventions. Responses were averaged to create a preventive care practice score. RESULTS: Of 295 eligible respondents, 179 returned completed surveys (61%). Eighty-one percent were male. Respondents did not vary by geographical area. However, female family physicians were less likely to respond than males, and olderfamily physicians were less likely to respond than more-recent graduates. On average, family physicians reported asking 79% of their adolescent patients about contraceptive use, 73% about condom use, 72% about sexual relationships, and 61% about sexual behaviors. Only 36% reported asking teens when they thought sex was appropriate, and 30% had discussed sexual orientation. Seventy-six percent of physicians discussed adolescents' risks of HIV with adolescent patients, 78% advised adolescent patients to use condoms, 21% gave handouts about HIV, and 9% gave condoms to adolescent patients. Factors associated with provision of more preventive reproductive services included regularly discussing confidentiality, more-recent medical school graduation, placing a high value on the American Academy of Family Physicians recommendations, having read Centers for Disease Control immunization guidelines, having read American Academy of Pediatrics guidelines, and female gender Overall, these factors explained 26% of the variance in provision of preventive reproductive services. CONCLUSIONS: Family physicians report providing most reproductive preventive services to more than half of their patients. Female physicians, older physicians, physicians who regularly discuss confidentiality, and physicians who have a more-positive attitude toward andfamiliarity with preventive care guidelines are more likely to provide reproductive health screening and counseling during adolescent visits.

Adolescent↗

PubMedDate not supplied

[Reproductive behavior of ethnic groups from Antioquia, Colombia].

OBJECTIVE: To identify the reproductive timing, intensity, and rhythm of the Embera, (Eyabida, Dobida, and Chamibida subgroups) and Zenues ethnic groups. MATERIAL AND METHODS: A sociodemographic study was conducted during 1996-1997 in Antioquia, Colombia, on a non-random population sample, stratified by ethnic group, to compare reproductive behaviors within and between these ethnic groups. Statistical analysis for independent samples was conducted using the software program Epi-Info. Analysis included the Student's t test for difference of means, and the chi-squared test for difference of proportions. RESULTS: Reproductive behavior was characterized by ages at first intercourse of 14.5 and 15.8 years; the average interval before pregnancy was 1 to 1.3 years, followed by 48% to 73.3% of short-spaced intergenesic intervals. Reproductive stress was 50% during reproductive life, reaching an accelerated rhythm at 30-34 years of age, with a high fecundity ratio averaging 10.5 births, except for the better educated Chamibida that had 4 births on average. CONCLUSIONS: Mainstream health policies directed at controlling birthrates are far from appropriate because they do not take into account the specific reproductive behaviors of these ethnic groups. The English version of this paper is available at: http://www.insp.mx/salud/index.html

Adolescent↗

PubMed2002

[Investigation of reproductive organs of male children and juvenile of the Meng and the Han nationality in Chifeng area].

OBJECTIVES: To investigate the development and the health of reproductive organs of male children and juvenile between the Meng and the Han nationality in the Meng nationality area. METHODS: Male juvenile(4-18 years old) of the Meng nationality (n = 2,315) and the Han nationality (n = 2,832) were divided into four age groups. Height, weight, length and perimeter of penis, volume of left and right testis and reproductive organs illness were examined. RESULTS: In 13-18 years group, the developmental speed of reproductive organs was faster in Mongolia male juvenile than that in the Han nationality (P < 0.02). After 13 years old, the developmental speed of reproductive organs of male living in town is faster than that in the country (P < 0.05). Illness of male reproductive organs was common such as hernia, varicocle etc. CONCLUSIONS: There was difference of developmental status and the prevalence rate of reproductive organs of male children and juvenile between the Meng and the Han nationality.

Adolescent↗

PubMed2003

Mechanisms linking nutrition and reproduction in postpartum cows.

The reproductive physiology of postpartum cows is different from that of heifers because of the combined effects of the past pregnancy and lactation. Neither lactation nor pregnancy has a major effect on postpartum fertility when calving is free from disease and lactation is moderate. Postpartum beef cows in good body condition have conception rates nearly equivalent to those of virgin heifers once their uteri are involuted and they initiate ovarian cycles. However, cows will experience infertility when nutrient requirements for maintenance and lactation exceed nutrient intake (postpartum beef cows) or when nutrients are specifically partitioned toward lactation (postpartum dairy cows). The subsequent loss of body fat that occurs in either case has effects on a variety of reproductive processes and reproduction becomes less efficient. The mechanisms that lead to abnormal reproduction in nutritionally compromised postpartum cattle have been investigated intensively. Much of the effort has focused on the nature of the signal (endocrine or otherwise) that controls pituitary secretion of LH and FSH, the response of the ovary to LH and FSH, and other ovarian effects that are independent of gonadotrophins. Reproductive studies in ruminants have tended toward studies of follicular development and this focus relates back to solving the problem of anoestrus. Less work has been done on the effects of nutrition on the early embryo, the health of which may be predetermined by factors affecting the oocyte within the preovulatory follicle. Few studies have examined the effect of nutrition on uterine function in postpartum cattle. Solutions to postpartum reproduction will probably arise from a variety of approaches that include traditional physiology as well as more modern genomic and proteomic technologies.

Adipose Tissue↗

PubMed2004

Zearalenone applied per os provides adverse effects in structure of chosen parts of bitch reproductive system.

Both earlier investigations and complete formulas of pet food for dogs show that professionally prepared pet food is based in 30% on the material of the plant origin. Our own investigations prove that animal feeding stuffs of the plant origin are very often vectors of many undesirable substances (including micotoxins) that are unfavourable for carnivores. Zearalenone is a micotoxin, which frequently occurs among them. It was revealed in pet food in quantities from 5.0-299.5 microg/kg. It is a very dangerous xenobiotic because of its quick and easy absorption in the organism after per os application in monogastric animals. It is also a sterid and despite its plant origin it binds estrogen receptors in the reproductive tract and causes its hypo- and dysfunction. It is clearly visible in young, growing organisms and those during the menopause. In bitches, dysfunctions of the reproduction system, such as: endometritis-pyometra syndrome, prolonged oestrus, ovarian cysts and others are often found. It is supposed that specific for this species hormonal regulation of the reproduction processes based on the long progesterone and prolactin cycles, and on high sensibility to estrogens plays an important role in the etiopathogenesis of these dysfunctions. The application of hormones in bitches in therapeutic and biotechnical (contraception) purposes are the other factors, which should be taken into account in this aspect. There are some suggestions that therapeutic management, unfortunately connected with mistakes in the medical art, is often a cause of pathological condition in a reproductive organ in bitches. However, another reason of these disorders may be that bitches take zearalenone with the commercial pet food. The long-lasting intake of the feed with a low dose of this micotoxin may be the factor, which complicates hormonal regulation of the reproduction processes and is the cause of many disorders. Our own pilotage investigations showed that application of zearalenone at a dose of 200 microg/kg b.w. for 7 days leads to apoptotic-like changes in granule cells in the bitch reproductive system, atresia of follicular cells and oedema and hyperplasia of the oviductal and uterine cells. They could also indicate a follicular phase of the oestrus cycle in bitch. However, it did not take place.

Animal Feed↗

PubMed2003

NTP-CERHR Monograph on the Potential Human Reproductive and Developmental Effects of Di-n-Octyl Phthalate (DnOP).

The National Toxicology Program (NTP) Center for the Evaluation of Risks to Human Reproduction (CERHR) conducted an evaluation of the potential for di-n-octyl phthalate (DnOP) to cause adverse effects on reproduction and development in humans. DnOP is one of 7 phthalate chemicals evaluated by the NTP CERHR Phthalates Expert Panel. These phthalates were selected for evaluation because of high production volume, extent of human exposures, use in children's products, and/or published evidence of repro- ductive or developmental toxicity. Available information indicates that there are no commercial uses of pure DnOP. However, DnOP comprises approximately 20% of the commercially important C6-10 phthalate mixture, which is used in flooring and carpet tiles, tarps, pool liners, and garden hoses. DnOP is approved by the FDA as an indirect food additive and is used in seam cements, bottle cap liners, and conveyor belts. The results of this evaluation on DnOP are published in an NTP-CERHR monograph which includes: 1) the NTP Brief, 2) the Expert Panel Report on the Reproductive and Developmental Toxicity of DnOP, and 3) public comments received on the Expert Panel Report. As stated in the NTP Brief, the NTP reached the following conclusions regarding the possible effects of exposure to DnOP on human development and reproduction. Limited studies in mice and rats show that high exposures to DnOP may cause adverse developmental effects, but no evidence of reproductive effects was observed. In a continuous breeding study, no adverse effects were observed in the treated parents or their offspring after dosed feed exposure of mice (approx. 1,800, 3,600, or 7,500 mg/kg body weight/day). Human exposure information for DnOP was not available but it was assumed that the general US population would be exposed to 3-30 mug/kg body weight/day, based upon the range of estimated exposures for DEHP. Based on this assumption, NTP concluded that there is negligible concern for effects on adult reproductive systems. Two developmental studies were evaluated by the panel. In the first study, pregnant rats were treated with 5,000 and 10,000 mg/kg body weight/day DnOP by intraperitoneal injection on gestational days 5, 10, and 15. Increased fetal malformations and reduced body weights were observed at both doses. In the second study, pregnant mice were treated by gavage with approx. 10,000 mg/kg bodyweight/day on gestational days 6-13 and were allowed to deliver the pups. The treated group had reduced litter size, but birth weights and pup survival to postnatal day 3 were not affected. These studies did not determine an exposure level at which no adverse effects occur. The NTP concluded that there is insufficient information on developmental toxicity to reach a conclusion regarding the potential for DnOP to adversely affect human development. NTP-CERHR monographs are transmitted to federal and state agencies, interested parties, and the public and are available in electronic PDF format on the CERHR web site (http://cerhr.niehs.nih.gov) and in printed text or CD-ROM from the CERHR (National Institute of Environmental Health Sciences, P.O. Box 12233, MD EC-32, Research Triangle Park, NC; fax: 919-316-4511).

Journal Article↗

PubMed2004

NTP-CERHR Monograph on the Potential Human Reproductive and Developmental Effects of Propylene Glycol (PG).

The National Toxicology Program (NTP) Center for the Evaluation of Risks to Human Reproduction (CERHR) conducted an evaluation of the potential for propylene glycol (PG) to cause adverse effects on reproduction and development in humans. PG was selected for evaluation because of the potential for widespread human exposure through its use in food, tobacco, pharmaceutical products, cosmetics, various paints and coatings and as an antifreeze and de-icing solution. PG is a small, hydroxy-substituted hydrocarbon used as a chemical intermediate in the production of unsaturated polyester resins and in the production of plasticizers. The results of this evaluation on PG are published in an NTP-CERHR monograph which includes: 1) the NTP Brief, 2) the Expert Panel Report on the Reproductive and Developmental Toxicity of Propylene Glycol, and 3) public comments received on the Expert Panel Report. As stated in the NTP Brief, the NTP reached the following conclusions regarding the possible effects of exposure to PG on human development and reproduction. There is negligible concern for adverse developmental and reproductive effects in humans at current, proposed, or estimated exposure levels. There is no direct evidence that exposure of people to PG adversely affects reproduction or development. Studies in pregnant laboratory animals at oral doses of PG greater than 1,200 mg/kg body weight/ day and up to 10,400 mg/kg body weight/day in mice, did not produce developmental toxicity in offspring. In a continuous breeding study, no effects on fertility were observed in male or female mice at doses up to 10,100 mg/kg body weight/day in drinking water. The pharmacokinetics of PG indicates that the lack of adverse effects observed in laboratory animals is relevant to humans. The rate-limiting step in PG metabolism is conversion to the more toxic lactaldehyde product by alcohol dehydrogenase. Studies indicate that this enzyme saturates in humans at doses 8-10- fold lower than in rats and rabbits, thus affording less toxicity in humans. It is estimated that the average daily intake of PG from food products in the US is 34 mg/kg body weight/day for a 70 kg person, which is over 300 -fold lower than the highest dose tested in laboratory animals. NTP-CERHR monographs are transmitted to federal and state agencies, interested parties, and the public and are available in electronic PDF format on the CERHR web site (http://cerhr.niehs.nih.gov) and in printed text or CD-ROM from the CERHR (National Institute of Environmental Health Sciences, P.O. Box 12233, MD EC-32, Research Triangle Park, NC; fax: 919-316-4511).

Journal Article↗