Biological aspects and self-evaluation of shiftwork adaptation

Summary Two male truck drivers working in a Brazilian cellulose plant and classifying themselves as well- and ill-adapted to a shiftwork schedule of 4 days-on and 1 day-off, participated in an autorhythmometric study. Psychophysiological self-ratings (calmness, stress and alertness), oral temperature measurements and urine collections (detection of K⁺,Na⁺ and 17-OH concentrations) were performed regularly during the waking period for 15 consecutive days during the shift schedule — the midday shift (11:00 to 19:00h), early-morning shift (03:00 to 11:00 h) and evening shift (18:00 to 02:00 h), including days-off. Cosine fitting of the data to a successive running one-day window revealed different individual temporal patterns, with the well-adapted subject showing a relatively stable phase relationship of the variables under study and the ill-adapted subject showing a less stable relationship. The different patterns could explain, at least partially, the fact that one subject feels adapted to shiftwork and the other not.Dedicated to the memory of Prof. Dr. Dr. Joseph Rutenfranz, former Director of the Institut für Arbeitsphysiologie, Dortmund, FRG, who contributed so much to the development of studies on occupational and environmental health     

Comprehensive pediatric primary care vs traditional care in an israeli population: Their influence on pediatric emergency room use and hospitalization

Emergency room (ER) utilization and hospitalization were studied as indicators of the impact of improvements in pediatric primary care services in an Israeli development town, Ofakim, population 12,000. One of the two pediatric services was upgraded in 1976 through the introduction of pediatric faculty, integration of preventive and curative services and conversion of the medical records to a problem-oriented format ( experimental clinic B ). The primary care system remained unchanged in the second clinic ( traditional clinic A ). During 1980, ER utilization by the B clinic population was 9.3/100 compared with 17.6/100 for the A clinic population. Fifty two percent of the B clinic population patients reaching the ER were hospitalized compared with 25% of A clinic patients.The lower ER utilization rate represents a significant saving for the health services, and educational interventions are suggested from the study. Analysis of ER utilization data seems to offer useful information for overall planning and monitoring of ambulatory services for a community.Corresponding author.     

Long-term effects of dinoseb and paraquat,both individually and combined,on embryonic development and hatching success ofFasciola hepatica miracidia

Toxic effects of the herbicides dinoseb and paraquat, both individually and combined, on embryonic development and hatching ofFasciola hepatica miracidia were assessed by exposing the eggs to varying concentrations (0–20 g/ml) of each of the herbicides. The results showed that dinoseb has an LC₅₀ value of 4.3 g/ml, paraquat has an LC₅₀ of 4.9 g/ml and the mixture of both dinoseb and paraquat has an LC₅₀ of 7.1 g/ml. Based on the LC₅₀ values, dinoseb is slightly more toxic than paraquat on the tested organisms. The results also showed that the mixture of dinoseb and paraquat is significantly less toxic than the individual pesticides.Eggs ofF. hepatica cultured in either dinoseb or paraquat both individually and combined showed a delay of embryonic development and hatching of the miracidia. Eggs cultured in 0–2 g/ml of dinoseb, paraquat and their mixture, fully embryonated and hatched within 14–16 days, while eggs cultured in 4–6 g/ml of the same herbicides showed a delay of four days for embryonic development and hatching of their miracidia.     

Pesticide residues in human colostrum: Seasonal variations,Yugoslavia

Levels of HCH, HCH, HCH,o,pDDE,p,pDDE andp,pDDT were measured in 59 samples of colostrum collected in the autumn 1982 and the spring 1983 from healthy nursing mothers on the third day after delivery. Pesticide residues were identified and quantitated on a gas chromatograph. Concentrations of HCH were significantly higher in the autumn (mean, 1.71g/L) than in the spring (0.67g/L), while concentrations of HCH were significantly lower in the autumn (0.49g/L) than in the spring (1.50g/L). The differences between the two seasons were not statistically significant for HCH (0.95 g/L vs 0.88g/L),o,pDDE (0.73g/L vs 1.34g/L),p,pDDE (68.63g/L vs 53.72g/L) andp,pDDT (20.00 (g/L vs 14.29 (g/L).Calculated average daily HCH (Lindane) intake of 0.04g/kg body wt (b.w.) and total DDT intake of 4.16 (/kg b.w. in a 3.5 kg newborn, ingesting 60 ml/kg b.w. of colostrum on the third day of life was below the upper limit of FAO/WHO Acceptable Daily Intake (ADI) (0.01 mg/kg b.w. for Lindane and 0.005 mg/kg b.w. for DDT) in the spring. In the autumn, Lindane intake of 1.10k/kg b.w. was below the FAO/WHO ADI and total DDT intake of 5.36 g/kg b.w. was slightly above the FAO/WHO ADI.     

In vitro susceptibility of mycelial and yeast forms of Penicillium marneffei to amphotericin B,fluconazole, 5-fluorocytosine and itraconazole

The mycelial (25°C) and yeast-like (37°C) forms of Penicillium marneffei clinical and type strains were investigated for their in vitro susceptibility to amphotericin B (AmB), 5-fluorocytosine (5-FC), fluconazole (FLU) and itraconazole (ITZ), using Bacto antibiotic medium 3, yeast-nitrogen, Sabouraud's dextrose (pH 5.7) and high resolution (pH 7.1) broth media (1ml/tube), respectively. Results indicated that the minimal inhibitory and minimal fungicidal concentrations (MICs and MFCs) for the mycelial cultures of P. marneffei to AmB were in the range 0.78–1.56 and 0.78–3.125 g/ml, respectively, as against 3.125–25 g (MICs) for the yeast form cultures. The MFCs to AmB for the yeast form were one dilution higher. The MICs to FLU were generally lower for the yeast form (6.25–25 g) than the mycelial form (25–50 g/ml), whereas MFCs for the mycelial cultures were > 100 g as compared to 6.25–100 g for their yeast form. The MICs for the mycelial form to 5-FC ranged from < 0.195–0.39 g. Higher MICs (6.25 g) were recorded for their yeast form. The MFCs to 5-FC for the yeast form were 25–100 g/ml. The MICs for the mycelial form to ITZ ranged from < 0.195 to 3.125 g/ml. Higher values (< 0.195–50 g) were recorded for their yeast-like form. The MFCs to ITZ for mycelial and yeast forms ranged from < 0.195–0.39 and 25–100 g/ml, respectively. Results indicate that P. marnefei's yeast form is more sensitive to FLU and ITZ (8 of 10 strains) while the mycelial form displayed greater susceptibility to AmB and 5-FC. The MICs for ITZ remained steady in SD medium, pH 5.7 to 7.1. However, some strains gave higher MIC values (0.39–1.56 g/ml) when tested in the HR.     

Effects of different dietary levels of cadmium,lead, copper,and zinc on the vitality of the forest pest insect Lymantria dispar L. (Lymantriidae,Lepid)

Lymantria dispar (gypsy moth) larvae were reared on both a natural diet of oak leaves and an artificial medium contaminated independently with four different metal nitrates. Larvae were contaminated up to pupation either from 1st or 4th instars at four concentrations differing by a factor of 5. The lowest concentration levels were 2 g/g Cd, 4 g/g Pb, 10 g/g Cu, and 100 g/g Zn based on nutrient medium dry weight. Developmental rate, growth, mortality and reproductive success were determined. No-Observed-Effect-Concentrations (NOECs) calculated were dependent on the metal, the parameter investigated and the stage at which exposure commenced. In general, larvae exposed from the 4th instar were less susceptible to metal toxification than those exposed from hatching. Considering all parameters investigated, dietary NOECs were determined to be 2 g/g Cd, 4 g/g Pb, 10 g/g Cu, and 100 g/g Zn.     

Health-related quality of life in a rare disease: Hereditary hemorrhagic telangiectasia (HHT) or Rendu–Osler–Weber Disease

The levels of the health-related quality of life (HR-QoL) were analyzed in hereditary hemorrhagic telangiectasia (HHT) patients. The Short Form-36 Health Survey (SF-36) was administered to 50 HHT patients and scores were compared to a cohort of 2301 normal subjects. Clinical variables were patient age, illness duration, number of epistaxis episodes in the previous year and hemoglobin levels. Physical functioning, physical role limitations, bodily pain, social functioning, emotional role limitations and the physical component scores were lower among females. In multivariable analyses increasing age was related to lower physical functioning (P<0.04), physical role limitations (P<0.008), bodily pain (P<0.05) and emotional role limitations (P<0.01), while higher hemoglobin levels improved physical functioning(€P<0.03). The number of epistaxis episodes was negatively associated with physical role limitations (€P<0.009), vitality (P<0.002), social functioning (P<0.001), physical component summary (€P<0.001) and bodily pain (P<0.01). Illness duration was negatively related to the mental component summary (P<0.004). HHT patients had a lower HR-QoL with respect to normal controls in all domains except for bodily pain. Females had lower scores for several domains. Epistaxis was the most important clinical variable.     

Polychlorobiphenyls, ΣDDT,and hexachlorocyclohexane isomers in the western North Pacific ecosystem

Polychlorobiphenyls (PCBs), DDT (p,p-DDT,p,p-DDD, andp,p-DDE and HCH isomers (hexachlorocyclohexanes including , , and isomers) were determined in a marine food chain, including seawater, zooplankton, myctophid, squid and striped dolphin collected from the western North Pacific waters. The concentrations of these pollutants increased in higher trophic levels, where the highest bioconcentration factors (concentration ratio in organisms to water), as much as 10⁷, were obtained from both PCBs and DDT in striped dolphin. The proportions of highly chlorinated biphenyls,p,p-DDE and -HCH increased in higher-ranking predators. These observations suggest that the bioaccumulation mechanisms in lower trophic levels depend primarily on the physicochemical properties of pollutants, whereas those in higher trophic levels are affected by the biodegradability of the pollutants and the metabolic capacity and life-span of the organisms.     

In a Secular Spirit: Strategies of Clinical Pastoral Education

The Clinical Pastoral Education (CPE) model forthe provision of spiritual care represents theemergence of a secularized professionalpractice from a religiously-based theologicalpractice of chaplaincy. The transformation ofhospital chaplaincy into spiritual careservices is one means by which religioushealthcare ministry negotiates modernity, inthe particular forms of the secular realm ofbiomedicine and the pluralism of thecontemporary United States healthcaremarketplace. Spiritual is a labelstrategically deployed to extend the realm ofrelevance to any patient's belief system,regardless of his or her religious affiliation.Theological language is recast as a tool forconceptualizing the spiritual lens. Suchmoves transform chaplaincy from a peripheralservice, applicable only to the few religiouspatients, into an integral element of patientcare for all. Such a secularized professionalpractice is necessary to demonstrate therelevance and utility of spiritual care for allhospital patients in an era of cost-containmentpriorities and managed care economics.     

Chromatographic determination of dicofol and metabolites in egg yolks

Egg yolk was spiked withp,p-dicofol (p,p-DCF) (0.1–2.0 g/gm),p,p-dichlorobenzophenone (p,p-DCBP) (0.1–2.0 (g/gm), and 1,1-bis(4-chlorophenyl)-2,2-dichloroethylene (p,p- DDE) (0.05–1.0 g/gm). The fortified egg yolk (2–5 g) was mixed with acetonitrile to extract non-fat organic materials. After removal of acetonitrile, the spiked chemicals were separated with a column chromatograph packed with acid alumina. Recovery efficiencies forp,p-DCBP andp,p-DDE were determined by gas chromatography, and forp,p-dicofol by high performance liquid chromatography. The recovery efficiencies forp,p-dicofol,p,p-DCBP andp,p-DDE were 77.2–93.8%, 84.1–101.1%, and 88.5–96.0%, respectively.     

Bromacil and diuron herbicides: Toxicity,uptake, and elimination in freshwater fish

Fathead minnows, 30 days old, were exposed to technical grade bromacil and diuron in flow-through tests to determine acute toxicity. LC₅₀ values for bromacil were 185, 183, 182 and 167 mg/L at 24, 48, 96, and 168 hr, respectively; and for diuron, 23.3, 19.9, 14.2, and 7.7 mg/L at 24, 48, 96, and 192 hr, respectively. Eggs, newly hatched fry, and juvenile fish were continuously exposed to lower concentrations of the herbicides for 64 days. Growth was significantly reduced (p 0.01) at the lowest bromacil exposure of 1.0 mg/L. Therefore, it was not possible to determine a no effect concentration. The no effect concentration for diuron was 33.4 g/L, while the lowest concentration which resulted in adverse effects was 78.0 g/L. Adverse effects at 78.0 g/L were an increased incidence of abnormal or dead fry immediately after hatch (p 0.01) and decreased survival throughout the exposure period (p 0.05). Neither herbicide accumulated significantly in fish tissue, as bioconcentration factors were <3.2 and 2.0 for bromacil and diuron, respectively. Rainbow trout (Salmo gairdneri) injected with radiolabeled bromacil or diuron eliminated over 90% of the radioactivity within 24 hr. Parent compound and metabolites were detected in the aquarium water in both cases. Metabolites of diuron recovered from the water included 3,4-dichloroaniline and several demethylated products.     

DDT,DDD, and DDE contamination of sediment in the Newark Bay estuary,New Jersey

Two hundred and forty-six surface and buried sediment samples from Newark Bay, New Jersey, and its major tributaries (Passaic River, Hackensack River, Newark Bay, Arthur Kill, Elizabeth River, and Kill Van Kull) were assayed for p,p-dichlorodiphenyltrichloroethane (p,p-DDT), p,p-dichlorodiphenyldichloroethane (p,p-DDD), and p,p-dichlorodiphenylchloroethylene (p,p-DDE) between February 1990 and March 1993. Chronological profiles in sediments from pre-1940 to the present were determined by radioisotope activities of ²¹⁰Pb and ¹³⁷Cs. The concentrations of these chemicals were compared to National Oceanic and Atmospheric Administration (NOAA) benchmark sediment values (Long and Morgan 1991). The objectives were to (a) determine the spatial and temporal distributions of DDT compounds in sediments, (b) identify possible sources, and (c) assess the potential for sediment toxicity within the estuary. Mean concentrations in surface sediments in individual waterways ranged from 5 to 473 g/kg for p,p-DDT, 18 to 429 g/kg for p,p-DDD, and 5 to 111 g/kg for p,p-DDE. A regional background mean concentration of approximately 100–300 g/kg p,p-DDT (sum of p,p-DDT, p,p-DDD, and p,p-DDE) was measured in surface sediments throughout the estuary, with the exception of the Arthur Kill, where mean concentrations exceeded 700 g/kg. The elevated concentrations found in recently deposited surface sediments in the Arthur Kill may be due to the presence of ongoing sources. The highest concentrations in buried sediments occurred in the lower Passaic River at depths corresponding to historical deposits from 1940 to 1970, the peak time period for production and usage of DDT in the United States. Comparisons to NOAA benchmark sediment toxicity values indicate that p,p-DDT, p,p-DDD, and p,p-DDE concentrations in surface sediments may pose a potential hazard to fish, shellfish, and other benthic and demersal organisms in some portions of the estuary, particularly in the upper and lower Arthur Kill.     

Fumigant contamination during large-scale food sampling for analysis

Incurred fumigants were determined from twenty-two food items before and after routine large-scale preparation of samples to see if these or similar kinds of chemicals were entering the samples during the preparation. This preparation includes making the samples table ready before compositing them for analysis. The following five fumigant residues were determined by gas chromatography (GC): carbon disulfide (CS₂), carbon tetrachloride (CCl₄), chloroform (CHCl₃), methyl chloroform (CH₃CCl₃), and tetrachloroethylene (or perchloroethylene, PCE). The number of residues determined from each sample ranged from none to four. The amounts determined varied significantly between the before and after portions from several samples. Four samples gained at least one new residue during the preparation. Six lost most of the residues determined from the original before portions, and 12 contained essentially the same residues before and after the preparation, although the amounts varied between the two portions. In samples where the variant residues were detected in both portions, five showed a tenfold or greater increase of CHCl₃ or CCl₄ and two showed a ten-fold or lesser decrease of CH₃CCl₃ or PCE in the after portions.     

Percutaneous absorption of N,N-dimethylformamide in humans

Summary Skin penetration fo N,N-dimethylformamide (DMF) liquid or vapour was studied in volunteers. Exposure to liquid DMF was performed in two ways: in a dipping experiment, one hand was dipped up to the wrist in DMF for 2–20 min, while in a patch experiment, 2 mmol DMF was applied to the skin and allowed to be absorbed completely. The period of exposure to DMF vapour (50 mg · m^–3) was 4 h. The DMF metabolites N-hydroxymethyl-N-methylformamide (MF), N-hydroxymethylformamide (F), and N-acetyl-S-(N-methylcarbamoyl)cysteine (AMCC) were monitored in the urine. Liquid DMF was absorbed through the skin at a rate of 9.4 mg · cm^–2 · h^–1. Percutaneous absorption of DMF vapour depended strongly on ambient temperature and humidity and accounted for 13%–36% of totally excreted MF. The results suggest that skin absorption of liquid DMF is likely to contribute to occupational exposure substantially more than penetration of DMF vapour. The yield of metabolites after transdermal DMF absorption was only half of that seen after pulmonary absorption. Elimination of MF and F but not that of AMCC was delayed, which supports the contention that AMCC should be used instead of MF as the most suitable biomarker of DMF in cases where percutaneous intake can occur.     

Disposition of β-hexachlorocyclohexane,p,p′-DDT,and trans-chlordane administered subcutaneously to monkeys (Macaca fascicularis)

To evaluate skin lipid analysis for the accumulation level of environmental pollutants, the correlations between organochlorine pesticide residues in adipose tissue, blood, and skin lipids of monkeys were studied. The mixture of -hexachlorocyclohexane (-HCH), p,p-DDT, and trans-chlordane was subcutaneously given to monkeys once weekly for 5 weeks at dose levels of 1 and 10 mg/kg. The chemicals distributed in adipose tissue, blood, and skin lipids were determined six times after the last dosing at intervals of 4 to 9 weeks.Oxychlordane and p,p-DDE were detected in all tissues together with the administered chemicals. In blood and adipose tissue, trans-chlordane decreased rapidly and oxychlordane and p,p-DDE increased gradually and then remained at constant levels. -HCH and p,p-DDT in adipose tissue increased until the 12th week and then decreased in all animals. The correlation coefficients between blood and adipose tissue regardless of dose level and collection time for each chemical ranged from 0.83 to 0.94. Correlation coefficients between skin lipids and adipose tissue varied with the chemical, namely, 0.31, 0.72, 0.81, 0.81, and 0.83 for p,p-DDE, tras-chlordane, p,p-DDT, -HCH, and oxychlordane, respectively. The results indicated that skin lipid analysis may be useful for the evaluation of specific pollutants in the body burden.     

Short-term exposure of zooplankton to the synthetic pyrethroid,fenvalerate, and its effects on rates of filtration and assimilation of the alga,Chlamydomonas reinhardii

In acute tests of toxicity, two cladocerans,Daphnia galeata mendotae andCeriodaphnia lacustris, and the calanoid,Diaptomus oregonensis, were more sensitive to fenvalerate thanDaphnia magna, the organism used in standard laboratory bioassays. The 48-hr EC₅₀s for each species/stage in order of increasing sensitivity were adultD. magna — 2.52 g/L;D. magna (48-hr old) — 0.83 g/L; adultD. galeata mendotae — 0.29 g/L; adultC. lacustris — 0.21 g/L;D. galeata mendotae (48-hr old) — 0.16 g/L; adultDiaptomus oregonensis — –0.12 g/L. No toxicity was observed when these organisms were exposed to a range of concentrations of the emulsifiable concentrate without fenvalerate (the EC blank).Rates of filtration of the¹⁴C-labelled alga,Chlamydomonas reinhardii byD. galeata mendotae, C. lacustris andD. oregonensis were decreased significantly at sublethal concentrations of fenvalerate after only 24-hr exposure.Ceriodaphnia lacustris showed the greatest sensitivity with rates of filtration significantly decreased at 0.01 g fenvalerate/ L. Concentrations of fenvalerate 0.05 g/L resulted in decreased rates of filtration byD. galeata mendotae. A concentration of 0.10 g fenvalerate/ L caused rates of filtration to increase inD. oregonensis. whereas 0.05 and 0.5 g/L resulted in a decrease in these rates.Rates of assimilation of algae byD. galeata mendotae, C. lacustris andD. oregonensis exposed to similar concentrations of fenvalerate were decreased at concentrations 0.05 g fenvalerate/L. Changes in rates of assimilation were not as sensitive a parameter of toxicity as changes in rates of filtration. The EC blank had no significant effects on rates of filtration or assimilation for all three species.     

Effects of 3,3′,4,4′,5-pentachlorobiphenyl (PCB 126) and 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) injected into the yolks of chicken (Gallus domesticus) eggs prior to incubation

The yolks of White Leghorn chicken (Gallus domesticus) eggs were injected prior to incubation with either 3,3,4,4,5- pentachlorobiphenyl (PCB 126) at doses ranging from 0.1 to 12.8 g/kg egg or 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) at doses ranging from 0.04 to 0.64 g/kg egg. Chicks were subjected to necropsy within 24 h of hatching. The brain, bursa, heart, liver, and spleen were removed and weighed. Assessment of the rate of hatching indicated an LD₅₀±S.E. of 2.3±0.19 g/kg egg (7.1±0.58 nmol/kg egg) for PCB 126 and 0.15±0.012 g/kg egg (0.47±0.037 nmol/kg egg) for TCDD. No significant differences in the incidence of developmental abnormalities (structural defects and edema) were observed in TCDD-exposed embryos, while PCB 126 caused significantly more developmental abnormalities at 3.2, 6.4, and 12.8 g/kg egg than the vehicle control. PCB 126 caused lower hatchling weights and greater relative brain, heart, and liver weights when compared to the vehicle control group at a dose of 3.2 g/kg egg which is greater than the LD₅₀. TCDD at 0.08 g/kg egg caused relative bursa weights to be less than those of the vehicle control. A toxic equivalency factor (TEF) of 0.07 was determined for PCB 126 in relation to TCDD based on overt lethality.     

Making sense of illness: late-in-life migration as point of departure for elderly Iranian immigrants' explanatory models of illness

This article is based on data gathered through 60 qualitative interviews conducted within the realm of three research projects that have used culture-appropriate lenses to study the postmigration situation of late-in-life Iranian immigrants to Sweden. The findings gathered through these studies were interpreted against the backdrop that culturally appropriate nursing theories provide. This meant that it was, at times, these elders backgrounds as cultural others that were implicitly used to make sense of the various issues that were brought to the fore by these studies. The particular issue with which this article is concerned is the unusualness of these elders explanatory models of illness. Inspired by the concept definition of situation in the symbolic interactionist perspective and by the feeling that this perspective might bring about a different interpretation of the original findings regarding their understandings of illness and disease, we set out to conduct a secondary analysis of these elders explanatory models of illness. The findings presented in this article will show how the elderly Iranian immigrants interviewed in these three studies utilize the process of late in life migration as a point of reference for their understandings of what has caused the illnesses from which they suffered. Hereby we will suggest that the unusualness of their explanatory models of illness might be best understood if we focus on what they shared as immigrants (i.e., the fact that the process of late-in-life migration has made their culture obsolete) as opposed to what they shared as Iranians (i.e., their culture of origin).     

Relationship between inhibition of erythrocyte pyrimidine 5′-nucleotidase activity and biological response for porphyrin metabolism in workers occupationally exposed to lead

Summary A rapid determination of erythrocyte pyrimidine 5-nucleotidase (P5N) activity in lead workers was carried out using a high-performance liquid chromatograph (HPLC). The P5N activity had a good negative correlation with the concentration of lead in blood (PbB) ranging from 16 to 96 g/dl (r = -0.82, n = 77). Further, the P5N was compared with other biological parameters: erythrocyte -aminolevulinic acid dehydratase (ALAD) activity, erythrocyte protoporphyrin (PROTO), urinary -aminolevulinic acid (ALA) and urinary coproporphyrin (COPRO).The correlation coefficients between P5N and ALAD, log PROTO, log ALA, and log COPRO were 0.59, –0.72, –0.65, and –0.61, respectively. On the other hand, the normal value of P5N obtained from 72 healthy subjects was 11.9 ± 2.1 units; ol uridine/h/g Hb (mean ± SD), indicating that the lower limit of 95% confidence interval for normal P5N was about 8 units. When P5N was cut off at 8 units in 77 lead workers, the validity (sensitivity + specificity) for PbB 40 g/dl, PbB 60 gg/dl, erythrocyte PROTO 150 g/dl RBC, urinary ALA 6 mg/l, and urinary COPRO 150 g/l was 1.66, 1.76, 1.57, 1.68, and 1.60, respectively. From these results, it was confirmed that the erythrocyte P5N test is suitable for the biological monitoring of exposure to lead in a wide range, and its activity is useful in predicting the disturbance of porphyrin metabolism induced by lead.     

Acute and chronic exposure of Dunaliella salina and Chlamydomonas bullosa to copper and cadmium: Effects on growth

Effective copper and cadmium concentrations which limited the growth of two chlorophytes by 50%, EC(50)s, after 96 h of static exposure were determined. EC(50)s were 5.94 gM copper and 4.55 M cadmium for Dunaliella salina, and 0.78 M copper and 0.025 M cadmium for Chlamydomonas bullosa. The relationship of the two cations was synergistic towards the growth of both species. Chronic exposure to 4.5×10^–6 M cadmium or 4.9×10^–4 M copper increased the sensitivity of C. bullosa by 26% and 29% towards cadmium and copper, respectively. Changes in co-tolerance were not observed. Cd-treated D. salina was 50% more tolerant towards this cation, whereas Cu-treated cultures showed extreme sensitivity towards copper and co-sensitivity towards cadmium. Furthermore, the phylogenetic hypothesis, predictive of toxic response, failed to hold at the familial level.This work was submitted by Ioanna Visviki to the Department of Biology of the Graduate School of the City University of New York in partial fulfillment of the requirements of the PhD degree.