Seasonal Foods: A New Menu for Public Health
In the article "Seasonal Foods: A New Menu for Public Health," the concept and practice of "the Global Food Basket" is discussed. The average "food mileage" or distance for food to travel from the farm to the supermarket is "1500 miles." This impacts the global carbon footprint and increases the consumption of natural and human resources to pick, package, preserve, pick up and drop off. In this article, alternatives to the global food basket was referred to as "Seasonal Foods," which are menus based off of locally grown products and produce. This is an arguably healthier alternative, because it offers variety according to the season, boosts local economies, reduces transportation pollution and other human resources. According to http://www.pickyourown.org/CAharvestcalendar.htm#northerncal, the produce that is in season for March 2017 in Northern California is asparagus. Because we are so fortunate for California's Mediterranean climate, there is a diversity of crops, produce and animals as food sources. California is fertile enough to yield grapes, avocados, corn, berries and most other fruits. Seasonal and local foods are opportunities for cost saving, especially for hospital menus, because it reduces time and costs involved in provider negotiations, transportation, packaging and preservation of the food.
Obesogens: An Environmental Link to Obesity
Prior to this module and reading the article "Obesogens: An Environmental Link to Obesity," I have never heard of "obesogens." In my pathophysiology courses, genetics, lifestyle and diet were always identified as risk factors for obesity and I am aware of medications and chemicals that alter hormone chemistry in the body that have outcomes of weight gain, but it is interesting to learn that chemicals in the our environment influence our genetic makeup and stimulate genes that cause weight gain and obesity. When an entire generation is identified as having gained weight or having a higher propensity for obesity, it truly signals that something is awry in the environment.
One of the "obesogens" in the article that I researched on toxnet was "tributyltin" or TBT. Blumberg's study on endocrine disruptors shows that TBT causes sex reversals in fish and that it triggers obesity in one generation of mice. This is significant, because we are exposed on a daily basis to TBT from industrial waste in our water systems that contaminates our food and fish supply that we consume. TBT has been identified as a chemical compound that changes animal metabolism.
As a healthcare professional, it is important to understand that being overweight and obese is largely influenced on only by lifestyle, diet and genetics, but now we must take into consideration of the effects of toxins in the environment.
TOXNET: Tributyltin
Animal Toxicity Studies:
Evidence for Carcinogenicity:
A4; Not classifiable as a human carcinogen. /Tin, organic cmpd, as Sn/
Non-Human Toxicity Excerpts:
Two classes of tributyltin resistant, spontaneous mutants of Escherichia coli K-12 were isolated, using a cytochrome containing (W 1485) and a cytochrome deficient (SASX76) strain. In contrast to the cytochrome sufficient strain, the cytochrome deficient strain was found to be fifty times more sensitive to tributyltin. The class I mutants, isolated from strain W 1485, also showed cross-resistance to triphenyltin. As compared to its wild type parent, the tributyltin-resistant mutants exhibited mucoid colony type, aberrant cell morphology and reduced uptake of tributyltin. Based on these results, it was suggested that the resistance of class I mutants to tributyltin may be associated with above mentioned alteration. The class II tributyltin-resistant mutants were isolated from the cytochrome deficient strain, SASX76. In comparison to class I mutants, these class II mutants were found to have tributyltin-resistant membrane bound adenosine triphosphatase (ATPase) which may account for their resistance to tributyltin.
Mud snails, Ilyanassa obsoleta, were collected along gradients of tributyltin pollution in the York River-Sarah Creek region of the Chesapeake Bay. Development of imposex (the imposition of male characters on female snails) was assessed. Frequencies of imposex & intensities of penis expression were either zero or very low at 3 sites in the York River where water concn of tributyltin were of the order of 2 ng/1 liter. In the northwest branch of Sarah Creek, with water concns of around 20 ng/1 liter, the frequency of imposex was 100% & the intensity of penis expression was high. Tissue concns of tributyltin were similar in both sexes & ranged from <20 ng/g 1 dry wt at the 3 York River sites to 620-730 ng/g 1 dry wt at a site in the northwest branch of Sarah Creek. An appreciable degree of imposex is induced in Ilyanassa obsoleta at a seawater tributyltin concn of about 10 ng/1 liter & imposex is probably initiated at about 2 ng/1 liter. No evidence was found for the fertilization of Ilyanassa obsoleta by imposex, but the % of females in the samples declined significantly with incr frequency of imposex.
Contamination of the Firth of Forth (Scotland) by tributyltin cmpds leached from antifouling paints has been identified using the degree of penis development (imposex) in the common dogwhelk Nucella lapillus. In 1987, a high degree of imposex was observed in the vicinity of pleasure craft activity, fishing harbors & a boat yard, reflecting localized inputs of tributyltin from these sources. Dogwhelks collected in 1975 from sites comparable to those surveyed in 1987 showed lower degrees of imposex & also a lower incidence of penis development in females.
The behavioral toxicity of an organic tin cmpd under consideration for use in marine antifouling paint was assessed using a Sidman avoidance paradigm. The assessed cmpd, an organometallic polymer (tributyltin(methacrylic-CO- methylmethacrylate) ester), is from a group of alkyltin cmpds of which triethyl & tributyltin are known to be toxic. Rats were tested under a free- operant avoidance procedure for 6 months while ingesting the polymer in their drinking water. At the beginning of the 5th month significant behavioral changes became evident, reflected in incr in shock rate, decr responding, & a shifting of the interresponse time distribution. Performance improved upon withdrawal of the contaminant suggesting that limited exposure to the polymer may not result in permanent behavioral dysfunction.
Repeated chronic toxicity experiments were conducted with the Chesapeake Bay zooplankton Acartia tonsa to evaluate its sensitivity to tributyltin. Experiments were initiated with Acartia tonsa nauplii <48 hr old. All tests were conducted with continious flow conditions & measured tributyltin concn. Results from a 9 day range finding experiment & two 6 day chronic experiments are presented. Tributyltin test concns were maintained with minimal fluctuations over time & toxicity results were similar in the repeated chronic experiments. The range-finding experiment demonstrated severe reductions in survival of Acartia tonsa at the lowest measured concn (0.29 ug tributyltin/l) In the 6 day experiments, 0.023 & 0.024 ug tributyltin/l were the lowest measured tributyltin concn to significantly reduce survival relative to the controls (ie, lowest observed effect concn (LOEC)). No observed effect concn (NOEC) measured at 0.012 & 0.010 ug tributyltin/l were used to calculate chronic values of 0.016 & 0.017 ug tributyltin/l for these two experiments. Acartia tonsa nauplii are very sensitive to tributyltin relative to other estuarine organisms. These toxicity data are environmentaly relevant since tributyltin concn exceeding the chronic value for Acartia tonsa have been reported from numerous locations in Chesapeake Bay.
The teratogenicity of tri-n-butyltin chloride was examined in Wistar rats. The pregnant rats were admin orally 25, 15, 9, 5 & 0 (Control) mg of tri-n-butyltin chloride/kg bw/day from day 7 to 15 of pregnancy. Maternal toxicity, as evidenced by both of decr body weight gain & food consumption was observed at 25, 15 & 9 mg/kg/day dose group. However, only in the 25 mg/kg/day dose group some clinical signs of toxicity (sedation, diarrhea & salivation) were observed & 70% of the dams were dead. In the 25 mg/kg/day dose group, all fetuses were dead. Statistically significant reductions in the female fetal body weight were observed in 9 & 5 mg/kg/day dose groups. In all groups treated with tri-n-butyltin chloride except the 25 mg/kg/day dose group, no significant differences in the numbers of live fetuses & intrauterine death (dead fetuses & resorptions) or sex ratios of fetuses were found between the tri-n-butyltin chloride treated & control groups. Fetal external, skeletal & internal malformations were not observed at any of the dose levels. However, several types of skeletal & internal variations including delayed ossifications were observed in some groups treated with tri-n-butyltin chloride, but the incidences were not significantly different from controls. Also two fetuses with dilatation of the renal pelvis were found in 9 & 5 mg/kg/day dose group. Statistically significant incr of placental weight in all tri-n-butyltin chloride treated groups were observed when compared to that of control group. In conclusion, tri-n-butyltin chloride admin orally to Wistar rats during days 7-15 of pregnancy produced related signs of fetal toxicity but no evidence of teratogenicity & induced a marked incr in placental weight. /Tri-n-butyltin chloride/
Imposex, the manifestation of male morphological sex characters in females of functionally dioecious neogastropod taxa, is an abnormal response to tri-n-butyltin contamination introduced to the marine environment in antifouling paints. Since the phenomenon has been thoroughly described only in Atlantic species, a comparative survey of field populations from British Columbia was undertaken, & field studies were carried out to assess the relative value as bionindicators of species in the genus Nucella from the Pacific coast. The majority of neogastropods to date have demonstrable signs of imposex, although this leads to sterilization of females in only a few species, depending on differences in the development in females of pallial vas deferens. Within the Nucella species complex, Nucella lamelloa, Nucella canaliculata, & Nucella emarginata show promise as tri-n-butyltin bioindicators. Only the response of Nucella emarginata, however, was related to tri-n-butyltin bioaccumulation, based on measurements of a limited number of samples. This is attributed to the apparent irreversibility of imposex, the temporal variability of both environmental levels & tissue burdens of tri-n-butyltin, & the considerably shorter life-span of nucella emarginata relative to that of Nucella lamellosa & Nucella canaliculata. The geographic distribution of imposex in Nucella species suggests that water-borne concns of tri-n-butyltin sufficiently high to induce imposex occur over large areas within British Columbia where exchange with oceanic water is limited.
The ability of organotin cmpds to inhibit gamma-aminobutyric-acid uptake was studied in male Swiss-Webster mice. The cmpds tested were trimethyltin; its tetramethyl, dimethyl, & monomethyl analogs; inorganic tin; triethyltin; tripropyltin; tributyltin; & triphenyltin. To study gamma-aminobutyric-acid uptake, mice forebrains were homogenated, & gamma-aminobutyric-acid or one of the organotin cmpds was added. Ouabain binding was also examined in mice forebrain homogenates. Activity of adenosine-triphosphatase was determined. All organotins containing three carbotin bonds were potent inhibitors of gamma-aminobutyric-acid uptake. Various thiol & sulfur cmpds, particularly sodium-sulfide, were capable of antagonizing the inhibitory effect of triphenyltin, & also the other organotins to a minor degree. All triorganotins also inhibited adenosine-triphosphatase activity. Although a correlation between inhibition of ouabain binding & gamma-aminobutyric-acid uptake by organotins could be found, inhibition of gamma-aminobutyric-acid uptake by the specific inhibitors ouabain & strophantidin was qualitatively & quantitatively different from that by organotins. /It was/ concluded that all triorganotins are capable of inhibiting synaptosomal gamma-aminobutyric-acid uptake by a mechanism involving, but not limited to, inhibition of adenosine-triphosphatase.
Exposure of Nucella lima (gmelin) to seawater or Mytilus trossulus (Gould) fresh containing tributyltin for 4 months resulted in the development of imposex, the superimposition of male reproductive tract characteristerics in female snails, in a time-dependent manner. Specific imposex characteristics measured in female snails included growth of a penis & vas deferens, & an incr in the magnitude of 2 imposex indices, relative penis size & the vas deferens sequence index. Imposex characteristics developed to a similar degree in snails fed tributyltin contaminated mussels (0.362 ug tributyltin/g wet weight) or exposed to 0.064 ug tributyltin/l in seawater by the 2nd month of exposure. After exposure to tributyltin for 4 months, intensification of imposex characteristics continued during a subsequent 10 month recovery period when snails were held in tributyltin free laboratory seawater & fed tributyltin free mussels. No significant differences in mortality & feeding rates occurred between control snails & those exposed to 0.064 ug tributyltin/l seawater or those exposed to tributyltin laden mussels; significant mortality & a decr feeding rate occurred in snails exposed to 0.914 ug tributyltin/l seawater, indicating that this concn is close to the long-term LC50. Tributyltin was bioaccumulated from both food & seawater in direct relationship to concn & length of exposure. Dibutylization of tributyltin occurred at a slow rate in all experimental groups, but a higher proportion of tributyltin was metabolized to dibutyltin & monobutyltin in snails exposed to 0.914 ug tributyltin/1 seawater. For Nucella lima, tributyltin bioaccumulation from food & resulting imposex responses are euivalent to low level exposures to tributyltin in seawater.
Between April & November, 1985, a study of the levels of organotins in adult & seed Crassostrea gigas grown in the southwest & southeast of England was carried out. This work corresponds with a similar study of organotin water levels (reported separately). The analytical procedure used was directly coupled high performance liquid chromatography-flame atomic absorption spectrometry. Individual adult oysters & groups of 20-40 seed oysters were taken for analysis on a monthly basis. The profiles of tributyltin, dibutyltin & monobutyltin are discussed in relation to each other & levels found in the waters. In general, levels of all three organotin species were found to be higher in the seed oysters. Mean levels of tributyltin reached 3.1 ug g/l in seed oysters from Exe, Devon, in October, whereas mean levels of dibutyltin & monobutyltin reached 16.1 & 16.7 ug g/l in Teign, Devon, seed oysters in October. Bioconcn factors of approx 1000 were found, but seem to be greater when lower levels of tributyltin were present in the water, perhaps indicating a more 'efficient' removal from the water. The degree of shell thickening was calculated for all oysters submitted for analysis. The highest % of adult oysters with severely thickened shells was found at Tollesbury Fleet, where 61% of oysters showed shell thickness index values of six or less. Generally, two peaks in tributyltin levels in the oysters were observed, in the late spring & early summer: these seem to correlate with peak levels of tributyltin in the waters immediately proceeding these times. A large proportion of dibutyltin & monobutyltin found in the oysters seems to come from the metabolism of the tributyltin ingested. It is suggested that high sediment loadings may contribute to the severe deformation of oysters grown at Tollesbury Fleet, but only in the presence of tributyltin.
I agree that the savings from purchasing organic product could reduce costs for hospital menus and reduce exposure to possible obesogens in commercialized products. However, I think many hospitals are still purchasing from mass production providers, which perpetuates the idea of convenience and supposed savings. I find this particularly true at the hospital I work at.
ReplyDeleteHi Allyssa,
ReplyDeleteLocal and organic foods are so important for health and agricultural sustainability. I especially agree with you about the concern you raise about our carbon footprint when transporting foods across long distances.