Abstract-Two sediment bioassay methods using Tubifex tubifex (Müller, 1774) as the test species were compared. The first was an adult reproduction test, the second an early-life-stage survival test. The duration of both bioassays is 28 d and the amount of work required was similar; they may be useful alternatives to each other in different circumstances (e.g., the early life stage bioassay could be carried out with smaller volumes of sediment). The two bioassays were performed simultaneously on copper-spiked sediments. Sediments from two freshwater and two terrestrial sites were used; five separate, nonsimultaneous experiments were performed, one for each sediment or soil and a further experiment with soil with a food supplement. In the adult bioassay, there were large differences in the production of cocoons, eggs, and young among the control treatments of the five experiments. There were also major differences in the NOEC (no-observed-effect concentration) and LOEC (lowest-observed-effect concentration) for copper between the tested substrates. The early life stage bioassay appears to be less sensitive to copper toxicity than the adult reproductive bioassay since NOECs and LOECs are higher for early survival than for the most sensitive endpoints of the adult bioassay in three experiments out of five.
This study examined the relationship between maternal exposure to stress during pregnancy and children's food preferences and diet in a population of low socioeconomic status. Methods: Indices of exposure to stress were constructed based on retrospective self-reported experience of stressful events during pregnancy (e.g., death of close family member, relationship difficulties, legal issues, health issues, financial issues, or other potentially stressful event[s]). Data were collected for >200 mothers of a low socioeconomic status with a child age 2 to 12 y. Data on mothers' body mass index, current exposure to stress, current diet, and diet during pregnancy were collected at the same time, as well as data on children's food preferences and current diet as reported by the mothers. Indices of the healthiness of food preferences and diet were constructed and used as outcome variables. Results: Maternal exposure to stress during pregnancy significantly predicts children's food and taste preferences, as well as their diet, in regression models controlling for maternal diet, current maternal stress, and demographic characteristics of both the child and mother. Higher average stress during pregnancy is linked with significantly less healthy food preferences and diet, as well as with weaker preferences for sour and bitter foods. This relationship is observed across different age groups. Conclusions: Maternal exposure to stress during pregnancy could have long-term detrimental effects on dietary outcomes and thereby on health conditions related to diet. Prenatal care and preconception counseling could be critical to develop preventive strategies to improve public health.
Sweet foods are commonly used as rewards for desirable behavior, specifically among children. This study examines whether such practice may contribute to reinforce the valuation of these foods. Two experiments were conducted, one with children, the other with rats. The first study, conducted with first graders (n = 214), shows that children who receive a food reward for performing a cognitive task subsequently value the food more compared to a control group who received the same food without performing any task. The second study, conducted on rats (n = 64), shows that rewarding with food also translates into higher calorie intake over a 24-hour period. These results suggest that the common practice of rewarding children with calorie-dense sweet foods is a plausible contributing factor to obesity and might therefore be ill advised.
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