Improving knowledge on genotoxicity dynamics in somatic and germ cells of crayfish (Procambarus clarkii).

The harmful effects of pesticides can be extended beyond the exposure time scale. Appraisals combining exposure and long-term post-exposure periods appear as an unavoidable approach in pesticide risk assessment, thus allowing a better understanding of the real impact of agrochemicals in non-target organisms. This study aimed to evaluate the progression of genetic damage in somatic and germ tissues of the crayfish Procambarus clarkii, also seeking for gender-specificities, following exposure (7 days) to penoxsulam (23 µg L-1 ) and a post-exposure (70 days) period. The same approach was applied to the model genotoxicant ethyl methanesulfonate (EMS; 5 mg L-1 ) as a complementary mean to improve knowledge on genotoxicity dynamics (induction vs. recovery). Penoxsulam induced DNA damage in all tested tissues, disclosing tissue- and gender-specificities, where females showed to be more vulnerable than males in the gills, while males demonstrated higher susceptibility in what concerns internal organs, that is, hepatopancreas and gonad. Crayfish were unable to recover from the DNA damage induced by EMS in gills and hepatopancreas (both genders) as well as in spermatozoa. The genotoxicity in the hepatopancreas was only perceptible in the post-exposure period. Oxidative DNA lesions were identified in hepatopancreas and spermatozoa of EMS-exposed crayfish. The spermatozoa proved to be the most vulnerable cell type. It became clear that the characterization of the genotoxic hazard of a given agent must integrate a complete set of information, addressing different types of DNA damage, tissue- and gender-specificities, as well as a long-term appraisal of temporal progression of damage.

Mother-level random effect in the association between PM2.5 and fetal growth: A population-based pregnancy cohort.

BACKGROUND: A growing body of literature reports associations between exposure to particulate matter with diameter ≤2.5 µm (PM2.5) during pregnancy and birth outcomes. However, findings are inconsistent across studies. OBJECTIVES: To assess the association between PM2.5 and birth outcomes of fetal growth in a cohort with high prevalence of siblings by multilevel models accounting for geographical- and mother-level correlations. METHODS: In Israel, we used Maccabi Healthcare Services data to establish a population-based cohort of 381,265 singleton births reaching 24-42 weeks' gestation and birth weight of 500-5000 g (2004-2015). Daily PM2.5 predictions from a satellite-based spatiotemporal model were linked to the date of birth and maternal residence. We generated mean PM2.5 values for the entire pregnancy and for exposure periods during pregnancy. Associations between exposure and birth outcomes were modeled by using multilevel logistic regression with random effects for maternal locality of residence, administrative census area (ACA) and mother. RESULTS: In fully adjusted models with a mother-level random intercept only, a 10-µg/m3 increase in PM2.5 over the entire pregnancy was positively associated with term low birth weight (TLBW) (Odds ratio, OR = 1.25, 95% confidence interval, CI: 1.09,1.43) and small for gestational age (SGA) (OR = 1.15, 95% CI: 1.06,1.26). Locality- and ACA-level effects accounted for <0.4% of the variance while mother-level effects explained ∼50% of the variability. Associations varied by exposure period, infants' sex, birth order, and maternal pre-pregnancy BMI. CONCLUSIONS: Consideration of mother-level variability in a region with high fertility rates provides new insights on the strength of associations between PM2.5 and birth outcomes.

The influence of biofilm maturation on fluoride's anticaries efficacy.

OBJECTIVES: (1) To explore the influence of biofilm maturation and timing of exposure on fluoride anticaries efficacy and (2) to explore biofilm recovery post-treatment. METHODS: Bovine enamel specimens were utilized in a pH cycling model (28 subgroups [n = 18]). Each subgroup received different treatments [exposure]: sodium fluoride [NaF]; stannous fluoride [SnF2]; amine fluoride [AmF]; and de-ionized water [DIW], at a specific period: early: days 1-4; middle: days 3-6; and late: days 7-10. During non-exposure periods, pH cycling included DIW instead of fluorides. Objective 1: part 1 (cycling for 4, 6, or 10 days). Part 2 (cycling for 10 days). Objective 2: early exposure: three sample collection time points (immediate, 3 days, and 6 days post-treatment); middle exposure: two sample collection time points (immediate, 4 days post-treatment). The enamel and biofilm were analyzed ([surface microhardness; mineral loss; lesion depth]; [lactate dehydrogenase enzyme activity; exopolysaccharide amount; viability]). Data were analyzed using ANOVA (p = 0.05). RESULTS: Objective 1: Early exposure to fluorides produced protective effects against lesion progression in surface microhardness and mineral loss, but not for lesion depth. Objective 2: Early exposure slowed the demineralization process. SnF2 and AmF were superior to NaF in reducing LDH and EPS values, regardless of exposure time. They also prevented biofilm recovery. CONCLUSION: Earlier exposure to SnF2 and AmF may result in less tolerant biofilm. Early fluoride treatment may produce a protective effect against demineralization. SnF2 and AmF may be the choice to treat older biofilm and prevent biofilm recovery. CLINICAL RELEVANCE: The study provides an understanding of biofilm-fluoride interaction with mature biofilm (e.g., hard-to-reach areas, orthodontic patients) and fluoride's sustainable effect hours/days after brushing.

The association between ambient PM2.5 exposure and the risk of preterm birth in China: A retrospective cohort study.

BACKGROUND: The relationship between PM2.5 exposure and preterm birth remains unclear. OBJECTIVES: To explore the effect of exposure to PM2.5 on preterm birth in China. METHODS: The birth outcomes of 426,246 pregnant women enrolled between January 2014 and December 2014 in NFPCP (National Free Pre-pregnancy Checkups Project) were collected, and their individual PM2.5 exposure values were estimated from the China National Environmental Monitoring Centre. The time of gestational exposure to PM2.5 was divided into four periods (the first trimester, the second trimester, the third trimester and the entire pregnancy). The average concentration and the corresponding quartiles of PM2.5 were calculated in these periods by the daily average PM2.5 data. Cox proportional hazards regression was used and he effects of maternal age, education level, occupation, second-hand smoking, alcohol use, pre-pregnancy BMI, baby's sex, number of previous pregnancies, coastal areas and season of conception were adjusted for. RESULTS: A total of 426,246 singleton births were included, among which 35,261 (8.3%) were preterm birth. Effect of each 10µg/m3 increase of PM2.5 on preterm birth was most significant during the third trimester (HR, 1.06; 95%CI, 1.06-1.07), and also significant during the first trimester (HR, 1.04; 95%CI, 1.03-1.04), the second trimester (HR, 1.02; 95%CI, 1.02-1.02) and the entire pregnancy (HR, 1.06; 95%CI, 1.05-1.06). Compared with the lowest quartile of PM2.5, other quartiles increased the risk of preterm birth, and were most significant during the third trimester (HR, 1.87; 95%CI, 1.69-2.06). Subgroup analysis showed that compared with other subgroups, women who were older than 30years, had low education level, worked as farmers, had male baby, had previous pregnancies, not live in coastal areas and pregnant in winter were more sensitive to PM2.5 exposure. CONCLUSIONS: Ambient PM2.5 exposure during pregnancy played an important role in the pregnancy process and increased the risk of preterm birth.

Phytotoxicity of silver nanoparticles to Lemna minor: Surface coating and exposure period-related effects.

Silver nanoparticles (Ag NPs) exponential production raises concern about their environmental impact. The effects of Ag NPs to aquatic plants remain scarcely studied, especially in extended exposures. This paper aims to evaluate Ag NPs effects in Lemna minor at individual and sub-individual levels, focusing on three variables: Ag form (NPs versus ions - Ag+), NPs surface coating (citrate vs polyvinylpyrrolidone - PVP) and exposure period (7 vs 14days). Endpoints were assessed at individual level (specific growth rate, chlorosis incidence and number of fronds per colony) and sub-individual level (enzymatic activities of catalase (CAT), guaiacol peroxidase (GPx) and glutathione-S-transferase (GST)). Generally, plants exposed to all Ag forms underwent decays on growth rate and fronds per colony, and increases on chlorosis, GPX and GST, but no effects on CAT. The most sensitive endpoints were specific growth rate and GPx activity, showing significant effects down to 0.05mg/L for Ag NPs and 3µg/L for Ag+, after 14days. Ag+ showed higher toxicity with a 14d-EC50 of 0.0037mg Ag/L. Concerning surface coating, PVP-Ag NPs were more deleterious on growth rate and fronds per colony, whereas citrate-Ag NPs affected more the chlorosis incidence and GPx and GST activities. The exposure period significantly affected chlorosis: 14days triggered a chlorosis increase in Ag+-exposed plants and a decrease in Ag NPs-exposed plants when compared to 7days. Ag NPs induced an oxidative stress status in cells, thus ensuing upregulated enzymatic activity as a self-defense mechanism. Since Ag NPs dissolution might occur on a steady and continuous mode along time, and the average longevity of fronds, we propose longer exposures periods than the recommended by the OECD guideline. This approach would provide more relevant and holistic evidences on the overall response of freshwater plants to Ag NPs in an ecological relevant scenario.

Assessment of species-specific and temporal variations of major, trace and rare earth elements in vineyard ambient using moss bags.

Since the methodological parameters of moss bag biomonitoring have rarely been investigated for the application in agricultural areas, two mosses, Sphagnum girgensohnii (a species of the most recommended biomonitoring genus) and Hypnum cupressiforme (commonly available), were verified in a vineyard ambient. The moss bags were exposed along transects in six vineyard parcels during the grapevine season (March‒September 2015). To select an appropriate period for the reliable 'signal' of the element enrichment in the mosses, the bags were simultaneously exposed during five periods (3 × 2 months, 1 × 4 months, and 1 × 6 months). Assuming that vineyard is susceptible to contamination originated from different agricultural treatments, a wide range of elements (41) were determined in the moss and topsoil samples. The mosses were significantly enriched by the elements during the 2-month bag exposure which gradually increasing up to 6 months, but Cu and Ni exhibited the noticeable fluctuations during the grapevine season. However, the 6-month exposure of moss bags could be recommended for comparative studies among different vineyards because it reflects the ambient pollution comprising unpredictable treatments of grapevine applied during the whole season. Although higher element concentrations were determined in S. girgensohnii than H. cupressiforme, both species reflected the spatio-temporal changes in the ambient element content. Moreover, the significant correlation of the element (Cr, Cu, Sb, and Ti) concentrations between the mosses, and the same pairs of the elements correlated within the species, imply the comparable use of S. girgensohnii and H. cupressiforme in the vineyard (agricultural) ambient. Finally, both the moss bags and the soil analyses suggest that vineyard represents a dominant diffuse pollution source of As, Cr, Cu, Ni, Fe, and V.

The effects of maternal and children phthalate exposure on the neurocognitive function of 6-year-old children.

The primary purpose of this study was to investigate the effects of phthalate exposure on the intelligence and attentional performance of 6-year old children when adjusting each other as covariates. We also investigated the differential effects of phthalate exposure on the intelligence and attention according to exposure period (maternal or children). Urine concentrations of mono-(2-ethyl-5-hydroxyhexyl) phthalate (MEHHP), mono-(2-ethyl-5-oxohexyl) phthalate (MEOHP), and mono-n-butyl phthalate (MBP) were analyzed. Multivariable linear regression models were used to investigate the relationship between exposure to various phthalates with IQ scores and continuous performance test (CPT) variables. There were robust associations between child MEHHP and MEOHP levels with full scale IQ (FSIQ) even after adjusting for demographic variables and CPT scores (MEHHP -9.27, 95% CI: -17.25, -1.29; MEOHP -9.83, 95% CI: -17.44, -2.21). Child MEHHP and MEHOP levels negatively affected omission errors (MEHHP -20.36, 95% CI: -34.17, -6.55; MEOHP -18.93, 95% CI: -32.58, -5.28) and the response time variability (MEHHP -21.07, 95% CI: -39.04, -3.10; MEOHP -20.41, 95% CI -38.14, -2.69) of the CPT after adjusting for demographic variables and IQ. Maternal phthalate exposure had no effects on IQ or CPT variables. These results suggest that children phthalate exposure, but not maternal exposure, has an adverse effect on IQ and attentional performance, and these associations were found to be independent of each other.

Oropharyngeal Tularemia Outbreak Associated with Drinking Contaminated Tap Water, Turkey, July-September 2013.

In 2013, an oropharyngeal tularemia outbreak in Turkey affected 55 persons. Drinking tap water during the likely exposure period was significantly associated with illness (attack rate 27% vs. 11% among non-tap water drinkers). Findings showed the tap water source had been contaminated by surface water, and the chlorination device malfunctioned.

Toxicity of phosphine on the developmental stages of rust-red flour beetle, Tribolium castaneum Herbst over a range of concentrations and exposures.

The susceptibility of the developmental stages of rust-red flour beetle, Tribolium castaneum to a range of concentrations of phosphine over varying durations from 24 to 168 h was reconnoitered in the laboratory at 25 ± 2 °C. Responses of the life stages exposed to phosphine were compared with those of un-treated controls over 24, 48, 72, 96, 120, 144 and 168 h exposures and mortality was assessed after 14 days. Among the life stages tested, pupae were more tolerant to phosphine followed by the egg and the larval instars. At 24 h, the maximum LC50 value was observed in case of egg; 1.571 mgL(-1); followed by the pupae, 6(th) instar, 4(th) instar and 2(nd) instar larvae with LC50 values of 1.184, 0.336, 0.212 and 0.081 mgL(-1) respectively. However, continued exposure of the developmental stages to phosphine, recorded maximum LC values in the pupae followed by egg and the larval instars. A linear increase in the mortality response was witnessed in all the insect stages when the exposure periods were extended from 24 to 168 h with increasing concentrations of phosphine, conversely significant increase in mortality was greatly apparent during the initial treatment periods.

Dependency of temporary threshold shift of vibratory sensation in fingertip on 1/3 octave-band hand-arm vibration exposure period.

OBJECTIVES: To investigate the dependency of temporary threshold shift of vibratoty sensation (TTS(v)) in fingertip on hand-arm vibration exposure period. METHODS: Six healthy students were instructed to grip a vibrating or nonvibrating handle in the experimental room. The gripping force was 40 N. The vibratory sensation threshold at 125 Hz was measured before and after the exposure in the exposed middle fingertip. The exposure vibration was vertical and the 1/3 octave-band vibration with had a central frequency of 200 Hz and an intensity of 39.2 m/s(2). The exposure periods were 8, 15, 30, 60, 120, 240 and 600 s. TTS(v,t) was evaluated as the difference in vibratory sensation threshold between immediately before and t seconds after the exposure. RESULTS: TTS(v) recovered exponentially as in several previous studies and its use enabled us to estimate the time constant and TTS(v,0). TTS(v,0) with vibration exposure was significantly larger than that without it. The regression analysis of the relationship between vibration exposure period (T) and TTS(v,0) (T) for each subject confirmed the good fit of the equation TTS(v,0)(T)=B(0)+B(1) (*)Log(10)(T), where B(0) and B(1) are the calculated constants (adjusted R(2)=0.56-0.87). The time constants did not show such a clear dose effect relationship of exposure period as TTS(v,0). CONCLUSION: The dependency of TTS(v,0) on vibration exposure period was asymptotically proportional to the logarithm of gripping period. To more quantitatively confirm the relationship of the time constants for recovering time course of TTS(v), it may be necessary to improve the measurement method for TTS(v).

Dependency of Temporary Threshold Shift of Vibratory Sensation in Fingertip on 1/3 Octave-Band Hand-Arm Vibration Exposure Period

Objectives: To investigate the dependency of temporary threshold shift of vibratoty sensation (TTSv) in fingertip on hand-arm vibration exposure period. Methods: Six healthy students were instructed to grip a vibrating or nonvibrating handle in the experimental room. The gripping force was 40 N. The vibratory sensation threshold at 125 Hz was measured before and after the exposure in the exposed middle fingertip. The exposure vibration was vertical and the 1/3 octave-band vibration with had a central frequency of 200 Hz and an intensity of 39.2 m/s2. The exposure periods were 8, 15, 30, 60, 120, 240 and 600 s. TTSv, t was evaluated as the difference in vibratory sensation threshold between immediately before and t seconds after the exposure. Results: TTSv recovered exponentially as in several previous studies and its use enabled us to estimate the time constant and TTSv, 0. TTSv, 0 with vibration exposure was significantly larger than that without it. The regression analysis of the relationship between vibration exposure period (T) and TTSv, 0 (T) for each subject confirmed the good fit of the equation TTSv, 0 (T) = B0 + B1 * Log10 (T), where B0 and B1 are the calculated constants (adjusted R2 = 0.56 − 0.87). The time constants did not show such a clear dose effect relationship of exposure period as TTSv, 0. Conclusion: The dependency of TTSv, 0 on vibration exposure period was asymptotically proportional to the logarithm of gripping period. To more quantitatively confirm the relationship of the time constants for recovering time course of TTSv, it maybe necessary to improve the measurement method for TTSv.

Dependency of temporary threshold shift of vibratory sensation in fingertip on 1/3 octave-band hand-arm vibration exposure period

<p><b>OBJECTIVES</b>To investigate the dependency of temporary threshold shift of vibratoty sensation (TTS(v)) in fingertip on hand-arm vibration exposure period.</p><p><b>METHODS</b>Six healthy students were instructed to grip a vibrating or nonvibrating handle in the experimental room. The gripping force was 40 N. The vibratory sensation threshold at 125 Hz was measured before and after the exposure in the exposed middle fingertip. The exposure vibration was vertical and the 1/3 octave-band vibration with had a central frequency of 200 Hz and an intensity of 39.2 m/s(2). The exposure periods were 8, 15, 30, 60, 120, 240 and 600 s. TTS(v,t) was evaluated as the difference in vibratory sensation threshold between immediately before and t seconds after the exposure.</p><p><b>RESULTS</b>TTS(v) recovered exponentially as in several previous studies and its use enabled us to estimate the time constant and TTS(v,0). TTS(v,0) with vibration exposure was significantly larger than that without it. The regression analysis of the relationship between vibration exposure period (T) and TTS(v,0) (T) for each subject confirmed the good fit of the equation TTS(v,0)(T)=B(0)+B(1) (*)Log(10)(T), where B(0) and B(1) are the calculated constants (adjusted R(2)=0.56-0.87). The time constants did not show such a clear dose effect relationship of exposure period as TTS(v,0).</p><p><b>CONCLUSION</b>The dependency of TTS(v,0) on vibration exposure period was asymptotically proportional to the logarithm of gripping period. To more quantitatively confirm the relationship of the time constants for recovering time course of TTS(v), it may be necessary to improve the measurement method for TTS(v).</p>