Prenatal exclusion of homocystinuria (cystathionine β-synthase deficiency) by assay of phytohaemagglutinin-stimulated fetal lymphocytes

Homocystinuria due to cystathionine β-synthase deficiency was excluded in a fetus at 23 weeks' gestation by demonstrating activity of the enzyme in fetal lymphocytes after stimulation by phytohaemagglutinin. Fetal blood sampling was carried out because two determinations of enzyme activity on cultured amniotic cells gave low, not fully diagnostic values.     

ATRAZINE AND METOLACHLOR OCCURRENCE IN SHALLOW GROUND WATER OF THE UNITED STATES, 1993 TO 1995: RELATIONS TO EXPLANATORY FACTORS1

ABSTRACT: Since 1991, the U.S. Geological Survey has been conducting the National Water Quality Assessment (NAWQA) Program to determine the quality of the Nation's water resources. In an effort to obtain a better understanding of why pesticides are found in shallow ground water on a national scale, a set of factors likely to affect the fate and transport of two herbicides in the subsurface were examined. Atrazine and metolachlor were selected for this discussion because they were among the most frequently detected pesticides in ground water during the first phase of the NAWQA Program (1993 to 1995), and each was the most frequently detected compound in its chemical class (triazines and acetanilides, respectively). The factors that most strongly correlated with the frequencies of atrazine detection in shallow ground‐water networks were those that provided either: (1) an indication of the potential susceptibility of ground water to atrazine contamination, or (2) an indication of relative ground‐water age. The factors most closely related to the frequencies of metolachlor detection in ground water, however, were those that estimated or indicated the intensity of the agricultural use of metolachlor. This difference is probably the result of detailed use estimates for these compounds being available only for agricultural settings. While atrazine use is relatively extensive in nonagricultural settings, in addition to its widespread agricultural use, metolachlor is used almost exclusively for agricultural purposes. As a result, estimates of agricultural applications provide a less reliable indication of total chemical use for atrazine than for metolachlor. A multivariate analysis demonstrated that the factors of interest explained about 50 percent of the variance in atrazine and metolachlor detection frequencies among the NAWQA land‐use studies examined. The inclusion of other factors related to pesticide fate and transport in ground water, or improvements in the quality and accuracy of the data employed for the factors examined, may help explain more of the remaining variance in the frequencies of atrazine and metolachlor detection.     

The recovery of selenious acid aerosols on glass fiber filters

Previous workers have shown that selenium is only partially trapped on a filter during air sampling. In some cases, these losses have been attributed to volatilization of selenium dioxide. Our results demonstrate that selenium dioxide, in the presence of moist air, is completely recovered (apparently as selenious acid aerosols) and that the previous shortfalls must be due to other selenium species as yet unidentified. Selenious acid aerosols in our study were formed by volatilizing selenium dioxide (approximately 3 mg) into a stream of moist ambient air (relative humidity, greater than 50%), and trapped on glass fiber filters using a high-volume air sampler. Selenium(IV) was ultrasonically extracted from the filter with water and analyzed by atomic absorption spectrometry. Selenious acid aerosols were trapped on the filters with high efficiency (105 +/- 5 percent) using a 50 minute sampling period. With an extended sampling period (24 hours) the recovery was 103 +/- 6 percent.     

Future directions in air-quality science,policy, and education

On February 12-15, 2001, more than 200 scientists, engineers, decision makers, and educators participated in a conference on the "Future Directions in Air Quality Research: Ecological, Atmospheric, Regulatory/Policy, and Educational Issues." Important perspectives are summarized from the keynote addresses of noted scientists and educators, as well as managers in government, industry, and public interest groups. Observations and recommendations are provided to stimulate further thought about how to increase opportunities to make greater use of scientific knowledge in air-quality decision making and to ensure that decisions are effective, economically viable, health and ecologically sound, and socially acceptable. Recommendations are given regarding ways in which communications between scientists and policy makers should be structured so as to make appropriate and effective use of scientists and the knowledge they can provide in policy-making fora.     

Methodological aspects of a national population-based study of persistent organochlorine compounds in serum

Key methodological aspects are presented for a study of concentrations of polychlorinated dibenzo-p-dioxins (PCDDs), polychlorinated dibenzofurans (PCDFs), polychlorinated biphenyls (PCBs), and organochlorine pesticides in the serum of a sample of the New Zealand population aged 15 years and older. The study took advantage of the sampling frame and sample collection and interview processes of the National Nutrition Study (NNS). An additional blood sample for this organochlorines study was collected by the NNS and questions added to the NNS questionnaire. Serum was obtained from the blood and, based on responses to questions in the questionnaire, samples with possible occupational exposure to organochlorines were excluded. Remaining samples providing at least 2 ml of serum were pooled within 80 strata defined according to geographic area, age group, sex and ethnicity. A minimum number of five individual serum samples was required for pooling within a stratum. Within strata with sufficient samples, two or three pooled samples were created for variance calculation. Eligible for inclusion in the study were 2497 individual serum samples. Sixty strata had sufficient serum samples for pooling and chemical analysis. This was the first study of organochlorine compounds with a national population-based sample. Two factors that made the study feasible deserve emphasis. First, being able to "piggy-back" on another study. Second, pooling of samples to reduce analytic expenses. It is hoped that the methods used in this study will form the basis for other studies investigating organochlorine concentrations in national populations.     

The evolving science of chemical risk assessment for land-applied biosolids

Biosolids, effluents, and manures are widely applied to agricultural land and other land with varying degrees of pretreatment or control. Regulations governing land application of biosolids take several broad forms in different countries, including limitations based on rates that do not lead to increases in background chemical concentrations or risk assessment approaches such as those used in the United States. Risk assessment is a process that is inherently limited by currently available information and practices, and consequently, risk-based land application limits must be reevaluated periodically. For complex mixtures such as biosolids, three principal categories of information will be affected by changing practices and scientific advances: (i) chemical constituents present in the material, (ii) the nature of expected exposures, and (iii) toxicity of the chemical constituents. New analytical methods and lower detection limits will affect chemical identification in wastes. Approaches to exposure assessment, such as increasing emphasis on probabilistic analyses, will continue to evolve, and exposure assumptions will change as new studies provide better data on factors such as soil ingestion, plant uptake of chemicals, and bioavailability of chemicals in soil. Similarly, toxicity assessments will be updated as new studies are conducted. The evolving science over the past decade is illustrated by comparing approaches used by the USEPA to assess human health and ecological risks for the Part 503 rule compared with the more recent evaluation of dioxins and related compounds in biosolids. While risks of chemicals in land-applied biosolids and other residuals need to be periodically re-evaluated, such re-evaluations may take forms other than full risk assessments.     

NITRATE CONCENTRATIONS IN GROUNDWATER BENEATH A BEEF CATTLE FEEDLOT1

ABSTRACT. A study of nitrate concentration in the groundwater beneath a beef cattle feedlot near Central City, Nebraska was started in 1968. An intensive 3-day pumping study was conducted at the feedlot at the start of 1970 irrigation system. Little nitrate concentration was found in the ground-water coming from beneath the feedlot. Pumping caused a slight increase in nitrate concentration over the average concentration for the previous 2 years.     

Bacterial sources,pathways and management strategies for urban runoff

The microbiological quality of diffuse impermeable surface runoff is described in terms of bacterial densities and pathogens observed within urban catchments in North London and Milton Keynes and the use of somatic bacteriophages as faecal indicators are evaluated. The studies show the occurrence of faecal indicator organisms (FIOs) and pathogens to be ubiquitous in stormwater runoff from all types of urban land use surfaces, with the possible exception of major highways. Urban catchments in North London show a progressive downstream increase in FIOs and pathogens consonant with increasing urbanization and incidence of stormwater outfalls and combined sewer overflows (CSOs). Surface water FIOs and pathogens appear to be predominantly of non‐human origin being primarily derived from animal and bird sources, although the effect is over‐ridden in the presence of misconnections and CSO discharges. A combination of infrastructure improvement, end‐of‐pipe detention, source control and more robust local authority regulation is recommended for effective management and remediation of bacteriological urban water quality.     

Small hive beetles survive in honeybee prisons by behavioural mimicry

We report the results of a simple experiment to determine whether honeybees feed their small hive beetle nest parasites. Honeybees incarcerate the beetles in cells constructed of plant resins and continually guard them. The longevity of incarcerated beetles greatly exceeds their metabolic reserves. We show that survival of small hive beetles derives from behavioural mimicry by which the beetles induce the bees to feed them trophallactically. Electronic supplementary material to this paper can be obtained by using the Springer LINK server located at htpp://dx.doi.org/10.1007/s00114-002-0326-y.     

Prenatal diagnosis of fragile X syndrome: Management of the male fetus with a premutation

Direct detection of the fragile X mutation by DNA analysis has greatly simplified prenatal diagnosis of this disease. However, women carrying a fragile X premutation may pass their expanded trinucleotide repeat to sons without expansion to a full mutation. Such sons are predicted to be intellectually normal. In this situation, the accuracy with which the fetal status can be inferred from analysis of chorionic villus sample (CVS) DNA is unclear. We describe such a case, in which it was felt necessary to proceed to fetal blood sampling despite technically unambiguous DNA results from the CVS. The lack of prospective data means that this dilemma may be expected to recur over the next few years when performing prenatal diagnosis on fragile X premutation carriers.