Steven C. Patch

Reducing Lead Exposure from Drinking Water: Recent History and Current Status

This article discusses the issue of lead contamination of drinking water, noting the various regulatory-driven measures that have been adopted in the U.S. since 1986 to address this public health issue. The article summarizes the literature on the dynamics of tap water lead contamination and discusses this widespread source of lead exposure in the context of the latest research evidence.

Effects of Deer Browsing on Native and Non-native Vegetation in a Mixed Oak-Beech Forest on the Atlantic Coastal Plain

Abstract We studied the effects of browsing by Odocoileus virginianus (white-tailed deer) on the native and non-native vegetation in a mixed oak-beech forest in Rock Creek Park, Washington, DC. We compared the thickness and cover of vegetation up to 2 m in height, and species richness of native and non-native plants in 17 exclosed (1 × 4 m) and 17 control plots from 2001–2004. Over the four-year period, foraging by deer suppressed the thickness of vegetation ≤ 1 m in height, reduced the cover of herbaceous, woody, and native plants, and generally decreased the species richness of native and woody plants. Browsing had no effects on the species richness of non-native plants, but generally reduced the prevalence of Celastrus orbiculatus (oriental bittersweet). Of the dominant canopy species, browsing affected Quercus spp. (oak) regeneration, but had no apparent effects on Fagus grandifolia (American beech). These results indicate that white-tailed deer are having a detrimental effect on the structure and species richness of native plants in this forest, and as a consequence, diminishing the value of the habitat for wildlife. In addition, white-tailed deer may help control the spread of oriental bittersweet in forest interiors, particularly where this species occurs at relatively low levels. If deer browsing is left uncontrolled in this forest, we predict that its future composition will shift towards one with fewer species and one dominated almost exclusively by American beech.

Systemic reactions with aeroallergen cluster immunotherapy in a clinical practice

BACKGROUND Subcutaneous allergen-specific immunotherapy is a proven, highly effective treatment for immunoglobulin E-mediated diseases. Despite its proven benefits, only a small percentage of patients with allergic disease use immunotherapy, in part because of the inconvenience associated with treatment. Cluster allergen immunotherapy may offer patients a more convenient treatment option but is prescribed infrequently because of the perception that accelerated immunotherapy buildup leads a higher rate of systemic reactions. OBJECTIVE To examine the safety of cluster immunotherapy and identify risk factors for systemic reactions during cluster buildup. METHODS A retrospective, observational review in a large, multicenter allergy practice group was conducted for patients receiving cluster immunotherapy between May 2008 and October 2010. RESULTS Data from 441 patients receiving cluster immunotherapy were collected. Forty-eight patients (10.9%) experienced systemic reactions. Based on the World Allergy Organization Subcutaneous Immunotherapy Systemic Reaction Grading System, 18 grade 1 reactions (38.3%), 23 grade 2 reactions (48.9%), 5 grade 3 reactions (10.6%), 1 grade 4 reaction (2.1%), and no grade 5 reactions were seen. Risk factors for a systemic reaction included: female sex, physician diagnosis of asthma, age 21 to 40 years, and inclusion of certain allergens in the immunotherapy vaccine. CONCLUSIONS Cluster immunotherapy allows patients to reach their immunotherapy maintenance dose more rapidly and may lead to more rapid symptomatic improvement. However, the cluster buildup may lead to a higher rate of systemic reactions. Identifying risk factors for systemic reactions will help improve the safety of cluster immunotherapy.

Microhabitat Selection by Eastern Box Turtles (Terrapene c. carolina) in a North Carolina Mountain Wetland

Abstract We investigated microhabitat selection by Terrapene carolina carolina in a North Carolina mountain wetland. We monitored a total of 21 radio-tagged turtles in 1997 and 1998. Turtles were located at least weekly from mid-May until they entered their overwintering sites. Microhabitat characteristics were quantified at each turtle location and at a corresponding random location < 25 m away. Weather varied during the study: 1998 was much hotter and drier than 1997. Microhabitat did not differ between males and females, except that females selected form locations with greater amounts of exposed soil. Overall, turtles constructed forms in areas that were more humid than the surrounding environment. Box turtles also used habitats with lower surface temperatures and higher humidity levels than the surrounding environment, particularly during hot and dry periods. This likely helped them regulate body temperature and prevent desiccation. During the summer of 1997 and all monitoring seasons in 1998, turtles were located at sites with moderate canopy cover and less understory plant cover than expected. Sites with less understory cover may have greater air circulation than those with more cover, thus allowing turtles to dissipate heat more rapidly. Amounts of woody debris, leaf litter, and canopy cover at turtle locations were similar to those available in the surrounding environment. Our results indicate that the attributes most important for defining the microhabitat of T. carolina (surface temperature, relative humidity, and understory plant cover) are related to thermoregulation and minimizing water loss.

The Dynamics of Lead in Drinking Water in U.S. Workplaces and Schools

A statistical analysis of water samples from over 12,000 school and workplace water coolers, bubblers, chillers, faucets, and ice makers determined that there is a substantial risk of excessive lead concentrations in first-draw water from sources of all types. Of all sources tested, 17.2% had lead concentrations in excess of 15 ppb. A comparison of lead concentrations by brand of water cooler was made for all manufacturers for which at least 50 samples were available. The percentage of water sources with first-draw lead concentrations above 15 ppb was reduced by 58%-84% by flushing the source prior to use. Special attention was given to determining the relationships between lead levels and factors such as water pH, water cooler age, and line purging. While each of these variables was found to be statistically significant, the overwhelming indication of this research is that testing individual water sources is apparently the only reliable way to determine whether a lead contamination problem exists.

A pilot simulation study of arsenic tracked from CCA-treated decks onto carpets

A controlled simulation experiment was performed to assess whether dislodgeable arsenic can be tracked onto carpets via foot traffic from chromated copper arsenate (CCA) pressure-treated decks. The pilot simulation study demonstrated that it is possible to track arsenic from CCA-decks onto carpets under the test conditions evaluated. A total of nine CCA-decks and two non-CCA-treated control surfaces were tested under wet and dry conditions. Five participants walked in a controlled manner (60 cycles, 11 steps per cycle) across decks and then walked over various lanes of carpet to simulate the tracking of arsenic indoors on the bottoms of shoes under heavy foot traffic conditions. To determine if arsenic was transferred from the CCA-treated wood to the carpet via shoes, laboratory analysis was performed on three different types of samples: (1) wipe samples of dislodgeable arsenic from a 46 cm(2) area of carpet, (2) dust samples obtained from vacuuming a 7442 cm(2) area of carpet, and (3) extractions of 13 cm(2) carpet samples. Wipe samples were also taken directly from the deck lumber. Following digestion and extraction, the amount of arsenic in each sample was measured using Graphite Furnace Atomic Absorption Spectrometry. The mean arsenic concentration measured on the carpets was 2.52 microg/(100 cm(2)) and 2.05 microg/(100 cm(2)) with wipes for the dry and wet conditions, respectively, 4.69 microg/(100 cm(2)) and 0.68 microg/(100 cm(2)) with vacuumed dust for the dry and wet conditions, respectively, and 15.56 microg/(100 cm(2)) and 12.31 microg/(100 cm(2)) with carpet extractions for the dry and wet conditions, respectively. The mean arsenic concentration measured on the decks was 22.2 microg/(100 cm(2)) with wipes. Further research is needed to determine if indoor exposure to arsenic due to track-in from outdoor decks via foot traffic is significant compared to exposures from other sources.

Impacts of Beaver Foraging on the Federally Threatened Virginia Spiraea (Spiraea virginiana) along the Cheoah River, NC

Abstract Spiraea virginiana (Virginia Spiraea) is a federally threatened shrub endemic to the southern Blue Ridge and Appalachian Plateau physiographic provinces. Observations along the Cheoah River, where the largest population of S. virginiana occurs in North Carolina, indicate that Castor canadensis (Beaver) feed on S. virginiana. However, the effects of Beaver foraging on this imperiled shrub are unknown. To address this issue, we randomly located 50 belt transects (25 m × 2.5 m) along the center of the scour zone of the Cheoah River and assessed all basal stems (<2.5 cm in diameter) of woody plants for evidence of browsing by Beaver. We recorded a total of 4963 basal stems, consisting of 59 species. Of those stems, 14.7% were browsed by Beaver. Spiraea virginiana accounted for 3.5% of the total basal stems and ranked fourth in the total number of stems browsed with 8.8%. After adjusting for transect effect, S. virginiana ranked second as a preferred forage species, with 32.0% of its stems browsed. This study suggests that overall browse levels of this community are relatively low compared to other communities inhabited by Beaver because of the high-gradient and turbulent nature of the Cheoah River. Our findings provide strong evidence that S. virginiana is an important food to Beaver, and as a consequence, Beaver foraging has the potential to affect this population. Although more information is needed to determine the long-term impacts, we suspect that in the short-term, S. virginiana may benefit from the levels of browsing found in this study. Field observations suggest that Beaver foraging stimulates asexual reproduction of S. virginiana by inducing rhizomatous growth. Beaver also may help S. virginiana with dispersal, as fresh cuttings are often left at feeding sites and then may be transported downstream for rooting.

Attributes of Shelters Selected by Eastern Hellbenders (Cryptobranchus a. alleganiensis) in the French Broad River Basin of North Carolina

Abstract We investigated the attributes of shelters used by Eastern Hellbenders (Cryptobranchus alleganiensis alleganiensis) in two 500-m stretches of the French Broad River basin in North Carolina during June 2010. We quantified attributes at each Hellbender shelter and at a corresponding unoccupied shelter located <25 m away to determine whether the attributes selected differed from those available in the surrounding environment. We identified 41 Hellbender shelters, each occupied by a single animal. Hellbenders selected shelters that had larger cover rocks and deeper cavities than the unoccupied shelters. No other attributes differed between occupied and unoccupied shelters, and there were no significant relationships between total length of Hellbenders and size of the cover rock or cavity depth. All Hellbender shelters were formed by large rocks with flat bottoms. Most had a single entrance that was oriented downstream and a cavity floor consisting of sand and gravel. Shelters were generally located in shallow, fast-flowing water with <10% of their surface area embedded in the substrate. Our results suggest that Hellbenders prefer shelters with attributes that maximize cavity space. Larger cavities likely provide greater protection from predators and greater concealment from sunlight. In addition, larger cavities allow more space for Hellbenders to rock back and forth to maximize oxygen uptake through their skin during periods of low flow when oxygen levels drop.

Description of Rich Montane Seeps and Effects of Wild Pigs on the Plant and Salamander Assemblages

Abstract Rich Montane Seeps are rare wetland communities endemic to high elevations of the southern Appalachian Mountains. Comprehensive data on the flora and fauna associated with these communities are lacking. Recent surveys indicate the rooting by nonnative wild pigs (Sus scrofa) may be affecting these communities. This study describes the abiotic and biotic features of Rich Montane Seeps across the Great Smoky Mountains National Park (GSMNP), investigates the effects of wild pigs on plant and salamander communities, and examines habitat attributes that influence pig disturbance. In our study a Rich Montane Seep was defined as any wetland with sheet flow occurring in hardwood forests above 1067 m. Pig disturbance and habitat attributes were measured in 1-m2 plots placed at 5 m intervals along a transect located on the longest axis of each seep. Habitat attributes measured included plant cover, plant richness, surface water, substrate, down woody debris, and shrub and tree densities (sampled in 3 m diameter circular plots). Salamanders were also sampled in each 1-m2 plot, identified to species when possible, and classified as larva, juvenile or adult. Thirty-five seeps, representing 24 drainages, were sampled. Rich Montane Seeps were characterized as small, linear wetlands with an open canopy, dense herbaceous vegetation, and few trees or shrubs. One hundred eighty species of plants (132 herbs, 35 shrubs, and 13 trees) and 10 species of salamanders (97 adults, 204 juveniles, 14 larvae) occurred in seeps, including eight plant species and three salamander species of conservation concern. Forty-nine percent of seeps and 54% of drainages had evidence of pig disturbance. Disturbance within seeps varied from 0-96% (mean  =  21%). Wild pigs negatively affected plant cover and plant richness. Wild pigs also had a negative effect on salamander surface density, but to a lesser extent than on plants. Amount of pig disturbance was negatively associated with slope. These results strongly suggest wild pigs are threatening the ecological integrity of Rich Montane Seeps across their range by negatively affecting the plant and salamander communities, particularly in seeps occurring on flat terrain.

Forage Selection of Native and Nonnative Woody Plants by Beaver in a Rare-Shrub Community in the Appalachian Mountains of North Carolina

Abstract Castor canadensis (Beaver) is a selective forager that can modify the species composition and structure of plant communities. However, no studies have examined the use of woody plants by Beaver in temperate forests that contain a dominant nonnative plant. We investigated foraging of woody plants by Beaver in a riparian shrub community that is dominated by both native and nonnative species, including the federally threatened shrub Spiraea virginiana (Virginia Spiraea). We established 48 random, 25-m transects along a 12-km reach of the Cheoah River in the Appalachian Mountains of North Carolina. We sampled woody plants every 5 m using a modified point-centered quarter method to estimate relative abundance and to quantify browsing by Beaver. We used a mixed linear model to determine Beaver forage selection on the 9 most abundant plant species and Virginia Spiraea. We recorded 984 plants of 58 woody species (55 native, 3 nonnative). Beaver browsed 24% of the woody species sampled and 8% of all stems. This finding suggests that the overall effects of browsing in this community were relatively low, likely because of the high gradient and turbulent nature of the Cheoah River. Relative stem abundance and location along the river did not differentially affect local levels of browsing. However, Beaver were selective foragers at both the species and individual-plant level. Of the 9 most abundant species, Carpinus carolinana (Musclewood), Liquidambar styraciflua (Sweetgum), and Alnus serrulata (Tag Alder) were selected most often; Lindera benzoin (Spicebush), Virginia Spiraea, Cornus amomum (Silky Dogwood), and Ligustrum sinense (Chinese Privet) were moderately selected. Least frequently selected species were Rhododendron maximum (Rosebay Rhododendron), Leucothoe fontanesiana (Doghobble), and Xanthorhiza simplicissima (Yellowroot). Browsing appeared to have a positive effect on both the invasive nonnative shrub, Chinese Privet, and the rare Virginia Spiraea by stimulating asexual reproduction and inducing plants to spread through suckering. This study demonstrates the importance of understanding the reproductive strategies of woody plants when gauging the community-wide effects of foraging by Beaver, particularly when an invasive plant species is present.