Life cycle assessment of biowaste and green waste composting systems: A review of applications and implementation challenges

Composting is one of the most widely applied methods for recycling organic waste. This process has been proposed as one option that facilitates the reincorporation of materials into the production cycle. However, composting also generates environmental impacts. Life Cycle Assessment (LCA) is the most common approach to evaluate the environmental impacts of a process at different system stages. Nevertheless, applying LCA in composting facilities is challenging due to the extensive information required, the lack of standardization on the initial assumptions, the definition of system boundaries, and the high diversity of existing composting technologies. This paper systematically reviews LCA studies in biowaste and/or green waste composting. The study highlights the challenges that should be met in order to improving the application of LCA to evaluate the environmental impacts of this type or waste treatment strategy. The review protocol used identified 456 papers published between 2010 and 2022. After the screening, 56 papers were selected, read, and thoroughly analyzed. The results show that: i) about 68% of the studies aimed to compare composting with other solid waste management options; ii) there was a wide diversity among the impact categories considered, which predominantly included climate change and ozone depletion; iii) there was no consensus on the functional unit or the system boundaries; iv) the main gaseous emissions studied were ammonia, methane, and nitrogen oxide, which were generally determined by emission factors; v) the avoided environmental impacts associated with the end-product quality and its application as an organic amendment or soil improver were ignored. This work demonstrates the complexity of conducting credible and valid composting LCA studies and proposes seven recommendations for improving the application of this assessment methodology to analyze this waste management alternative.

Induction of nuclear catechol-O-methyltransferase by estrogens in hamster kidney: implications for estrogen-induced renal cancer

Catecholestrogens are postulated to contribute to carcinogenesis by causing DNA damage mediated by reactive oxygen species generated during redox cycling between catechol and quinone estrogens, and by quinone estrogens that can form depurinating adducts. The above hypothesis is based principally on studies of the cancers that develop in renal cortex of hamsters treated with primary estrogens: Hamster kidney can catalyze 2- and 4-hydroxylation of estrogens and support their redox cycling, and the kidneys of estradiol-treated hamsters show evidence of oxidative cellular and DNA damage. Here we used immunocytochemisty to test the postulate that catechol-O-methyltransferase (COMT), the enzyme that can prevent oxidation of catecholestrogens to their quinone derivatives, would be induced in renal cortex of hamsters treated with estradiol or ethinyl estradiol. In kidneys of control hamsters, COMT was localized in cytoplasm of epithelial cells of proximal convoluted tubules, predominantly in the juxtamedullary region where the estrogen-induced cancers arise. After 2- or 4-weeks of treatment with either estrogen, COMT was seen in epithelial cells of proximal convoluted tubules throughout the cortex, and many cells also showed intense nuclear COMT immunoreactivity. Estradiol-induced renal cancers were negative for COMT, but were surrounded by tubules with intense cytoplasmic and nuclear immunostaining. The nucleus-associated COMT was shown by immunoblot analysis to be the soluble form of the enzyme. Using reverse transcription-polymerase chain reaction amplification, hamster kidney COMT was shown to lack the putative nuclear localization signal sequence present in human COMT. A second phase II enzyme, CuZn-superoxide dismutase (CuZnSOD), was shown by immunocytochemistry to remain extranuclear in proximal convoluted tubules of estrogen-treated hamsters, which indicates entry of COMT into the nucleus to be selective. The findings are consistent with the catechol/quinone estrogen hypothesis of estrogen-induced cancer, while the translocation of the enzyme to the nucleus following estrogen treatment suggests a response to a threat to the genome by electrophilic products of catechols.

Squamous cell tumors and ocular prostheses

Conjunctival squamous cell carcinoma is an infrequent tumor. It has been reported to occur in association with actinic damage and chronic irritation. To the authors' knowledge, however, this tumor has not been reported secondary to poorly fitting ocular prostheses. Two patients were studied in whom conjunctival squamous cell carcinoma had developed. In both instances, the patient had been enucleated and fitted with an ocular prosthesis more than 40 years before tumor development. Histopathologic evaluation of each tumor revealed its squamous cell origin. In one of the patients, the tumor was found to be metastatic to the ipsilateral parotid gland, an uncommon finding. The authors attempted to identify risk factors that may have contributed to the development of these tumors. Aside from the poor fit of the prostheses, neither patient had significant risk factors for the development of conjunctival squamous cell carcinoma. It is concluded that a new, sanguineous conjunctival discharge or focal eyelid swelling after years of prosthetic wear may not be due to mechanical irritation alone. The onset of these symptoms, especially years after the initial fitting of an ocular prosthesis, should prompt a thorough investigation of its cause.

Diabetic glomerulosclerosis and chronic renal failure with absent-to-minimal microalbuminuria

We report the case of an elderly black woman with a 20-year history of insulin-independent diabetes mellitus (IDDM), chronic renal failure, hypertension, proliferative retinopathy, and classical histologic features of diabetic glomerulosclerosis on renal biopsy. Repeat determinations of urinary albumin excretion rates failed to disclose significant microalbuminuria. This presentation should remind the clinician that a small minority of patients with IDDM of long duration may have severe diabetic glomerulosclerosis and renal insufficiency without detectable microalbuminuria.