Maternal residential proximity to hazardous waste sites and risk for selected congenital malformations

Using data from two population-based case-control studies, we investigated whether maternal residential proximity to hazardous waste sites increased the risk for neural tube defects, conotruncal heart defects, and oral cleft defects in California. We obtained a residential history by interview for mothers of 507 neural tube defect cases (82.7% of eligible) and their 517 controls (84.6%); and 201 heart cases (84.4%), 439 cleft cases (82.2%), and their 455 controls (72.1%). We identified the locations of 764 inactive hazardous waste sites and systematically collected information on site-related contamination for the subset of 105 National Priority List sites. After controlling for several potential confounders, we found little or no increased risk for maternal residence in a census tract containing a site [odds ratio (OR) = 0.9, 95% confidence interval (CI) = 0.7-1.3 for neural tube defects; OR = 1.3, 95% CI = 0.8-2.1 for heart cases; OR = 1.2, 95% CI = 0.8-1.8 for clefts], but elevated risks for neural tube defects (OR = 2.1, 95% CI = 0.6-7.6) and heart defects (OR = 4.2, 95% CI = 0.7-26.5) for maternal residence within 1/4 mile of a National Priority List site. Furthermore, we observed elevated ORs (> or = 2.0) for neural tube defects and heart defects in association with maternal residence within 1 mile of National Priority List sites containing selected chemical contaminants. Among controls, only 0.6% and 4.4% lived within 1/4 mile and 1 mile of a National Priority List site, respectively, resulting in imprecision in risk estimation.

Evaluation of cyanide exposure and its effect on thyroid function of workers in a cable industry

A thyroid-hormone evaluation of workers dealing with cyanide compounds in an electroplating process of a cable industry was carried out. Serum thiocyanate (SCN) levels of 35 nonsmoking copper-ply employees were assayed by a ferric-chloride color test. The mean SCN concentration of these employees was 316 +/- 15 mumol/L, which was significantly (P < 0.01) higher than that of control subjects (90.8 +/- 9.02 mumol/L). Serum thyroxine (T4), triiodothyronine (T3), and thyroid-stimulating hormone (TSH) concentrations of exposed workers were compared with those of 35 control subjects. Cyanide exposure resulted in a decrease in T4 and T3 concentrations (P < 0.05) and an increase in TSH concentration (P < 0.05), compared with the control subjects. The serum T4 level was found to be negatively correlated (r = -0.363, P < 0.05), whereas the TSH level was positively correlated (r = 0.354, P < 0.05), with SCN concentration in the exposed group. The study suggests that occupational cyanide exposure in the industry impairs thyroid function.

Chemistry, toxicology, and human health risk of cyanide compounds in soils at former manufactured gas plant sites

Cyanide-containing wastes are commonly found in soils at former manufactured gas plant (MGP) sites, also known as town gas sites. The complex forms of cyanide are responsible for the blue-stained soils and rocks found at these sites. Most concentrations of cyanide at MGP sites are below 2000 ppm, although concentrations greater than 20,000 ppm have been observed. An understanding of the chemistry of the MGP cyanide-containing compounds, their fate, and transport as well as their toxicology is critical to accurately assessing potential human health risks from these compounds. In this paper, the authors demonstrate that the most prevalent types of cyanide compounds found at former MGP sites are the relatively nontoxic iron-complexed forms, such as ferric ferrocyanide, rather than the highly toxic free cyanide forms. Moreover, the chemical conditions at most former MGP sites limit the extent to which free cyanide may be released into air and water from complex cyanides. Using a screening analysis, the authors estimate potential risks from a multiroute exposure to complex and free cyanides in soil, air, and groundwater at former MGP sites and demonstrate that such risks are likely to be insignificant. Unfortunately, the lack of readily available measurement techniques to characterize cyanides in soil can result in erroneous conclusions about potential risks from cyanide compounds in soils at former MGP sites, particularly if health-based soil criteria for free cyanide (e.g., the Massachusetts Department of Environmental Protection criterion for free cyanide is 100 ppm (MA. DEP, 1995)) are applied. The authors recommend development of routine methods for field sampling and laboratory testing techniques to demonstrate that cyanides in soil at former MGP sites are predominated by iron-complexed species and that free cyanide is less than levels of concern.

Konzo in the Central African Republic

We identified a new focus of konzo, an upper motor neuron disease, in a part of western Central African Republic. Interviews and high serum levels of thiocyanate indicate that cyanide exposure from insufficiently processed cassava may cause konzo. Abrupt onset, nonprogressive course, and seronegativity to HTLV-I clearly differentiate konzo from HTLV-I-associated myelopathy in tropical countries.

Cyanide toxicity. Agency for Toxic Substances and Disease Registry

Cyanide is one of the most rapidly acting poisons. Cyanide poisoning is a hazard that may accompany enclosed-space fires, and its occurrence in persons with smoke-inhalation injuries may be underestimated. Acute cyanide exposure primarily causes central nervous system, cardiovascular and respiratory effects. Thyroid function abnormalities have been noted in persons chronically exposed to cyanide. Initial symptoms may be nonspecific. Death may occur in seconds after acute inhalation of hydrogen cyanide.

ATP synthase activity is required for fructose to protect cultured hepatocytes from the toxicity of cyanide

The contributions of the loss of the mitochondrial membrane potential (MMP) and a depletion of ATP to the genesis of lethal injury were evaluated in the killing of cultured hepatocytes by cyanide (CN). The glycolytic production of ATP from fructose (Fru) maintained the MMP and prevented the killing by CN. Inhibition of the mitochondrial ATP synthase by 0.1 micrograms/ml oligomycin (Oligo) reduced ATP stores at the same rate and to the same extent as did 1 mM CN. With Oligo there was no loss of the MMP, and the hepatocytes maintained viability over the 6 h during which CN killed all of the cells. Oligo had no effect on the rate of killing by CN. However, Oligo reversed the protective effect of Fru on CN-induced killing, a result that correlated with the loss of MMP but not with the depletion of ATP. Neither Fru nor Oligo affected the intracellular acidosis achieved with CN alone. Fru also prevented toxicity of the uncoupler carbonyl cyanide m-chlorophenylhydrazone (CCCP), a result that correlated with the preservation of MMP. Oligo potentiated the toxicity of CCCP. It is concluded that a functioning mitochondrial ATP synthase is required for the production of ATP from Fru to prevent the killing of hepatocytes by CN. The extent of killing correlated closely with changes in the MMP but not with changes in the content of ATP.

Cerebral energy metabolism in cyanide encephalopathy

This study documents the effects of an intracarotid artery injection of a lethal threshold amount of KCN (2.5 mg.kg-1) on the energy metabolism and histology of the rat brain. This dose of KCN resulted in a rapid abolition of electroencephalographic activity, which remained essentially absent for up to 3 h. Cerebral metabolite measurements 0.25 h after KCN infusion indicated a 52% reduction in cytochrome oxidase activity, a 600% increase in lactate, a 32% reduction in ATP, a 73% increase in ADP, and an 85% decrease in glycogen. Measurements of the above energy metabolites over the ensuing 7 days showed a return to control of all metabolites by 6-24 h. Corresponding to the normalization of energy metabolism was a return of EEG and conscious activity. Histological examination of cyanide-exposed animals revealed a paucity of change with only one animal at 0.5 h showing several dark neurons, two animals at 1 h with minor pallor of corpus callosum and caudate-putamen, and one animal at 48 h with a small hippocampal infarction. It is concluded that it may be impossible to produce a serious enough disruption of cerebral metabolism with KCN injection, to produce neuronal damage by purely "histotoxic" mechanisms.

Diabetes and cassava in Dominica

A study of 110 non-insulin dependent diabetics and 110 controls failed to find evidence that chronic consumption of cassava flour containing significant amounts of cyanide, predisposes to diabetes mellitus.

Hepatic disease associated with ground-glass inclusions in hepatocytes after cyanamide therapy

In a retrospective review of 2400 consecutive liver biopsy specimens, 60 cases with ground-glass hepatocytes were identified, 41 specimens gave a positive reaction to orcein stain and 19 a negative staining. These 19 specimens were obtained from chronic alcoholics who had been admitted to a detoxication program that used aversive drugs and who were hepatitis B surface antigen negative. The use of cyanamide (Colme), an inhibitor of aldehyde dehydrogenase could be documented in 11 instances. In addition to ground-glass hepatocytes, which were periodic acid-Schiff positive and had a periportal or paraseptal distribution, these liver specimens showed a variety of hepatic lesions: cirrhosis in five cases, portal and periportal inflammation in six, triaditis in five, portal fibrosis in two, and minimal changes in one. Patients with shorter courses of cyanamide were those who had less severe histologic lesions. In three patients who had a liver biopsy carried out before the cyanamide treatment ground-glass hepatocytes were not found. These data indicate that ground-glass hepatocytes that stain with periodic acid-Schiff may develop after cyanamide treatment. They are associated with structural hepatic damage of varied severity in patients submitted to a long-term treatment.

Vitamin B nutrition in the Nigerian tropical ataxic neuropathy

Assessment of nutritional status of vitamin B components by plasma or blood levels indicated riboflavin deficiency and possibly thiamine deficiency in Nigerian patients who suffered from tropical ataxic neuropathy and neurologically normal Nigerians who subsisted on predominant cassava diet. Serum levels of folate, niacin, pyridoxine and panthothenic acid were normal. Vitamin deficiencies probably are minor factors, if any, in the pathogenesis of tropical ataxic neuropathy in Nigerians.

Structural hepatic changes associated with cyanamide treatment: cholangiolar proliferation, fibrosis and cirrhosis

The authors present the clinical and histological findings in a series of 42 liver biopsies from 39 chronic alcoholics treated with cyanamide as aversion therapy. All biopsies displayed characteristic cytoplasmic inclusions in the liver-cells. Fibrosis and disruption of the parenchymal-connective tissue interface were observed in all cases. According to the severity and extension of fibrosis, three stages could be depicted: Stage I. Periportal activity cholangiolar type (ACT), which is defined by cholangiolar proliferation, fibroblastic activation and inflammatory infiltrate, which together cause a blurred appearance of the parenchymal-connective tissue junction. It is the elementary lesion and was observed alone in 26 biopsies. Stage II. Portal-to-portal linkage. It was observed in 10 biopsies, all of which also showed periportal ACT. Three of these came from patients with two biopsies in which transition from stage I (first biopsy) to stage II (second biopsy) was observed. Stage III. Nodular parenchymal regeneration, associated with changes observed in stage I and II. It was found in six patients. The histological picture resembles the biliary type of cirrhosis. There is a clear-cut correlation between the length of treatment and the stage of the hepatic lesion.

[Pathology in firemen]

Fire fighters' respiratory organs, circulatory system and muscular system are often exposed to considerable risks. In fact in addition to the most obvious external stress causes (heat, humidity, O2 decrement, CO2 increment, emotional stress) these workers use heavy equipments and carry people or things. Furthermore always present is the risk of poisoning by inhalation of toxic combustion gas of the fire atmosphere.