Good News: Some Insecticides Have Been Virtually Eliminated in Air near the Great Lakes.

Persistent insecticides have been classic environmental problems for 60-70 years─perhaps starting with Rachel Carson's indictment of DDT. Both national and international regulations have been put in place over the last 20-30 years to eventually eliminate these compounds from the environment. One focus is the atmosphere, which acts as a major long-range transport route of these pollutants from their numerous sources to many ecosystems. This paper will ask, "Have we have made any progress in eliminating insecticides from the atmosphere?" We will focus only on the atmosphere around the North American Great Lakes and only on concentration measurements made once every 12 days since about 1990 for six classic insecticides. The answer is that some of these compounds (lindane, α-HCH, and endosulfans) are well on their way to being virtually eliminated, while the concentrations of others (DDT, chlordane, and hexachlorobenzene) have not changed much. We speculate that this difference in elimination is a result of soil compaction in cities (DDT, etc.) versus soil mixing in rural areas (lindane, etc.).

Polycyclic Aromatic Hydrocarbons in the Atmosphere near the Great Lakes: Why Do Their Concentrations Vary?

Polycyclic aromatic hydrocarbon (PAH) concentrations were measured in atmospheric samples collected at five sites near the shores of the North American Great Lakes once every 12 days from 1997 to 2018 (inclusive). These data were analyzed using multiple linear regression statistics to isolate the environmental variables controlling these PAH concentrations. About 74% of the variability is related to the number of people living and working within 25 km of the sampling site. Clearly, urban areas are major sources of PAH to the atmosphere. PAH concentrations at all sites lumped together are decreasing with halving times of about 25 years, and this factor represents about 1.5% of the variability. This is slower than the halving times for most banned compounds because PAH continue to be emitted directly into the atmosphere from many combustion sources. In the atmosphere, the concentrations of relatively volatile PAH maximize in July, but those of relatively nonvolatile PAH maximize in January. This seasonality factor represents about 2.5% of the variability. PAH concentrations at these Great Lakes sites tend to be elevated when the wind is coming out of the south-southeast, and this factor represents about 1.2% of the variability. PAH concentrations are lower when the wind speed is higher; this is a significant but small effect, representing only about 0.17% of the variability. The sum of these partial variabilities is about 80%, which suggests that the measurement and sampling errors are about 20%, which is a reasonable value. On the basis of two approaches, the range of atmospheric PAH transport from these sites is estimated to be on the order of 100-200 km. For these data, meteorology matters, but not by much.

Broad Exposure of the North American Environment to Phenolic and Amino Antioxidants and to Ultraviolet Filters.

The present study provides a comprehensive investigation of three suites of commonly used synthetic additives: phenolic and amino antioxidants and ultraviolet filters. The concentrations of 47 such compounds and their transformation products were measured in 20 atmospheric particle samples collected in Chicago, in 21 Canadian e-waste dust samples, in 32 Canadian and United States' residential dust samples, and in 10 sediment samples collected from the Chicago Sanitary and Ship Canal. Despite their large production volumes in the United States, environmental data on antioxidants and UV filters in North America is limited. These compounds were detected in all the samples, indicating their ubiquitous distribution in the North American environment. The most prevalent compounds were 2,6-di-t-butyl-p-benzoquinone, diphenylamine, 4,4'-di-t-octyl diphenylamine, 2,4-dihydroxybenzophenone, and 2-hydroxy-4-methoxybenzophenone. The e-waste dust contained significantly greater total concentrations of these compounds than the Canadian residential dust, while intermediate levels were detected in the United States residential dust. The sediment samples showed relatively high levels of N,N'-diphenylbenzidine, the source of which is unclear, and some benzotriazole UV filters. Daily intake rates by dust ingestion for these compounds ranged from 1-10 ng/(kg·day) for adults to 10-100 ng/(kg·day) for toddlers. Due to the wide distribution of these compounds in both the ambient and built environments, future research on their potential toxic effects on people and ecosystems is important.

Statistical Approach for Assessing the Stockholm Convention's Effectiveness: Great Lakes Atmospheric Data.

The implementation of the Stockholm Convention (SC) in 2004 should become evident in decreases in environmental concentrations of various pollutants even in countries that not have ratified the SC. However, in some cases, there may be no decreases at all. This paper develops a statistical strategy for investigating time-series measurements such that the rate of change of a pollutant's concentrations at any time can be compared to those at an earlier or later time and thus determine the effectiveness of the SC at any location. The general approach is to modify a first-order regression to include a second order time term: ln(Ct)= a0 + a1 t + a2 t2, where Ct is the concentration at time t. Thus, the rate constant at any time is k(t) = a1 + 2 a2 t. Given that the errors associated with a1 and a2 can be calculated, one can compare the rate constants at different times with statistical rigor to determine if the rates at which the concentrations are changing are significantly different. As examples of this approach, this paper uses vapor and particle phase atmospheric concentrations of several organic pollutants measured at six sites around the North American Great Lakes every 12 days since about 1992. After correcting for the population near the sampling sites, for seasonality, and for the different numbers of samples collected on the same date, up to 830 data were used in this second-order regression. In general, the loss rates of vapor phase chlorinated pesticides have slowed by about a factor of 2 between 1995 and 2015, which is not SC-like behavior. The exceptions are the endosulfans, the vapor and particle phase concentrations of which were both doubling in 1995 but were both decreasing in 2015, probably because of the greatly diminished use of this insecticide in the United States over the last 20-25 years. The loss rates of vapor phase polychlorinated biphenyls became more rapid between 1995 and 2015, which is SC-like behavior.

Spatial and Seasonal Distributions of Current Use Pesticides (CUPs) in the Atmospheric Particulate Phase in the Great Lakes Region.

The authors analyzed spatial and seasonal variations of current use pesticides (CUPs) levels in the atmospheric particulate phase in the Great Lakes basin. Twenty-four hour air samples were collected at six sites (two urban, two rural, and two remote) in 2015. The concentrations of 15 CUPs, including nine pyrethroid insecticides, four herbicides, one organophosphate insecticide, and one fungicide, were measured. The total CUPs concentrations were higher at the urban sites (0.38-1760 pg/m3) than at the rural and remote sites (0.07-530 pg/m3). The most abundant CUPs were pyrethroid insecticides at the urban sites. The levels of the other CUPs did not vary much among the six sites, except at the most remote site at Eagle Harbor, where the levels were significantly lower. Chlorothalonil was the most frequently detected CUP, which was detected in more than 76% of the samples. The atmospheric concentrations of total pyrethroid insecticides and total herbicides were correlated with local human population and developed land use. Significantly higher concentrations of most CUPs were observed in the warmer months than in the colder months at all sites. In addition to agricultural applications, which occur during the warmer months, the CUPs atmospheric concentrations may also be influenced by nonagricultural activities and the urban development.

Tri(2,4-di- t-butylphenyl) Phosphate: A Previously Unrecognized, Abundant, Ubiquitous Pollutant in the Built and Natural Environment.

Using high-resolution mass spectrometry, we identified tri(2,4-di- t-butylphenyl) phosphate (TDTBPP) in e-waste dust. This is a previously unsuspected pollutant that had not been reported before in the environment. To assess its abundance in the environment, we measured its concentration in e-waste dust, house dust, sediment from the Chicago Ship and Sanitary Canal, Indiana Harbor water filters, and filters from high-volume air samplers deployed in Chicago, IL. To provide a context for interpreting these quantitative results, we also measured the concentrations of triphenyl phosphate (TPhP), a structurally similar compound, in these samples. Median concentrations of TDTBPP and TPhP were 14 400 and 41 500 ng/g, respectively, in e-waste dust and 4900 and 2100 ng/g, respectively, in house dust. TDTBPP was detected in sediment, water, and air with median concentrations of 527 ng/g, 3700 pg/L, and 149 pg/m3, respectively. TDTBPP concentrations were generally higher or comparable to those of TPhP in all media analyzed, except for the e-waste dust. Exposure from dust ingestion and dermal absorption in the e-waste recycling facility and in homes was calculated. TDTBPP exposure was 571 ng/kg bw/day in the e-waste recycling facility (pro-rated for an 8-h shift), and 536 ng/kg bw and 7550 ng/kg bw/day for adults and toddlers, respectively, in residential environments.

Current-Use Flame Retardants in the Water of Lake Michigan Tributaries.

In this study, we measured the concentrations of 65 flame retardants in water samples from five Lake Michigan tributaries. These flame retardants included organophosphate esters (OPEs), brominated flame retardants (BFRs), and Dechlorane-related compounds. A total of 59 samples, including both the particulate and the dissolved phases, were collected from the Grand, Kalamazoo, Saint Joseph, and Lower Fox rivers and from the Indiana Harbor and Ship Canal (IHSC) in 2015. OPEs were the most abundant among the targeted compounds with geometric mean concentrations ranging from 20 to 54 ng/L; OPE concentrations were comparable among the five tributaries. BFR concentrations were about 1 ng/L, and the most-abundant compounds were bis(2-ethylhexyl) tetrabromophthalate, 2-ethylhexyl 2,3,4,5-tetrabromobenzoate, and decabromodiphenyl ether. The highest BFR concentrations were measured in either the IHSC or the Saint Joseph River. The dechlorane-related compounds were detected at low concentrations (<1 pg/L). The fraction of target compounds in the particulate phase relative to the dissolved phase varied by chemical and tended to increase with their octanol-water partition coefficient. The chemical loading from all the five tributaries into Lake Michigan were <10 kg/year for the BFRs and about 500 kg/year for the OPEs.

Updated Polychlorinated Biphenyl Mass Budget for Lake Michigan.

This study revisits and updates the Lake Michigan Mass Balance Project (LMMBP) for polychlorinated biphenyls (PCBs) that was conducted in 1994-1995. This work uses recent concentrations of PCBs in tributary and open lake water, air, and sediment to calculate an updated mass budget. Five of the 11 LMMBP tributaries were revisited in 2015. In these five tributaries, the geometric mean concentrations of ∑PCBs (sum of 85 congeners) ranged from 1.52 to 22.4 ng L-1. The highest concentrations of PCBs were generally found in the Lower Fox River and in the Indiana Harbor and Ship Canal. The input flows of ∑PCBs from wet deposition, dry deposition, tributary loading, and air to water exchange, and the output flows due to sediment burial, volatilization from water to air, and transport to Lake Huron and through the Chicago Diversion were calculated, as well as flows related to the internal processes of settling, resuspension, and sediment-water diffusion. The net transfer of ∑PCBs is 1240 ± 531 kg yr-1 out of the lake. This net transfer is 46% lower than that estimated in 1994-1995. PCB concentrations in most matrices in the lake are decreasing, which drove the decline of all the individual input and output flows. Atmospheric deposition has become negligible, while volatilization from the water surface is still a major route of loss, releasing PCBs from the lake into the air. Large masses of PCBs remain in the water column and surface sediments and are likely to contribute to the future efflux of PCBs from the lake to the air.

Development of Gas Chromatographic Mass Spectrometry.

Gas chromatographic mass spectrometry is now widely used for the quantitation and identification of organic compounds in almost any imaginable sample. These applications include the measurement of chlorinated dioxins in soil samples, the identification of illicit drugs in human blood, and the quantitation of accelerants in arson investigations, to name just a few. How did GC/MS get so popular? It turns out that it required parallel developments in mass spectrometry, gas chromatography, and computing and that no one person "invented" the technique. This Perspective traces this history from the 1950s until today.

Halogenated flame retardants in the Great Lakes environment.

Flame retardants are widely used industrial chemicals that are added to polymers, such as polyurethane foam, to prevent them from rapidly burning if exposed to a small flame or a smoldering cigarette. Flame retardants, especially brominated flame retardants, are added to many polymeric products at percent levels and are present in most upholstered furniture and mattresses. Most of these chemicals are so-called "additive" flame retardants and are not chemically bound to the polymer; thus, they migrate from the polymeric materials into the environment and into people. As a result, some of these chemicals have become widespread pollutants, which is a concern given their possible adverse health effects. Perhaps because of their environmental ubiquity, the most heavily used group of brominated flame retardants, the polybrominated diphenyl ethers (PBDEs), was withdrawn from production and use during the 2004-2013 period. This led to an increasing demand for other flame retardants, including other brominated aromatics and organophosphate esters. Although little is known about the use or production volumes of these newer flame retardants, it is evident that some of these chemicals are also becoming pervasive in the environment and in humans. In this Account, we describe our research on the occurrence of halogenated and organophosphate flame retardants in the environment, with a specific focus on the Great Lakes region. This Account starts with a short introduction to the first generation of brominated flame retardants, the polybrominated biphenyls, and then presents our measurements of their replacement, the PBDEs. We summarize our data on PBDE levels in babies, bald eagles, and in air. Once these compounds came off the market, we began to measure several of the newer flame retardants in air collected on the shores of the Great Lakes once every 12 days. These new measurements focus on a tetrabrominated benzoate, a tetrabrominated phthalate, a hexabrominated diphenoxyethane, several brominated benzenes, and a highly chlorinated norbornene compound called Dechlorane Plus. Most recently, we have begun measuring the atmospheric concentrations of several organophosphate esters, which are an increasing part of the flame retardant market. The interesting feature of this story is how one compound or set of compounds has followed another out of and into the marketplace even though none of them have been officially regulated. This replacement of one commercial product by another with similar functions shows that the chemical industry does respond to scientific environmental measurements and to the resulting bad publicity. This is a good thing. The problem is that often the replacement chemicals also become environmentally ubiquitous.

Hair and Nails as Noninvasive Biomarkers of Human Exposure to Brominated and Organophosphate Flame Retardants.

After the phase-out of polybrominated diphenyl ethers (PBDEs), the use of alternative flame retardants (AFRs), such as FireMaster 550, and of organophosphate esters (OPEs) has increased. However, little is known about human exposure to these chemicals. This lack of biomonitoring studies is partially due to the absence of reliable noninvasive biomarkers of exposure. Human hair and nails can provide integrated exposure measurements, and as such, these matrices can potentially be used as noninvasive biomarkers of exposure to these flame retardants. Paired human hair, fingernail, toenail, and serum samples obtained from 50 adult participants recruited at Indiana University Bloomington campus were analyzed by gas chromatographic mass spectrometry for 36 PBDEs, 9 AFRs, and 12 OPEs. BDE-47, BDE-99, 2-ethylhexyl-2,3,4,5-tetrabromobenzoate (TBB), di(2-ethylhexyl) tetrabromophthalate (TBPH), tris(1,3-dichloro-2-propyl)phosphate (TDCIPP), and triphenyl phosphate (TPHP) were the most abundant compounds detected in almost all hair, fingernail, and toenail samples. The concentrations followed the order OPEs > TBB+TBPH > Σpenta-BDE. PBDE levels in the hair and nail samples were significantly correlated with their levels in serum (P < 0.05), suggesting that human hair and nails can be used as biomarkers to assess human exposure to PBDEs.

Spatial and Temporal Trends of Particle Phase Organophosphate Ester Concentrations in the Atmosphere of the Great Lakes.

The concentrations of six organophosphate esters (OPEs) in atmospheric particle phase samples collected once every 12 days at five sites in the North American Great Lakes basin over the period of March 2012 to December 2014, inclusive, are reported. These OPEs include tris(2-chloroethyl) phosphate (TCEP), tris(2-chloroisopropyl) phosphate (TCIPP), and tris(1,3-dichloroisopropyl) phosphate (TDCIPP), tri-n-butyl phosphate (TNBP), triphenyl phosphate (TPHP), and 2-ethylhexyl diphenyl phosphate (EHDP). Median total OPE concentrations (∑OPE) ranged from 93 pg/m3 at Sleeping Bear Dunes to 1046 pg/m3 at Chicago. The ∑OPE levels were significantly (P < 0.05) higher at Chicago and Cleveland, our urban sites, than at our rural and remote sites. The composition profiles were dominated by chlorinated OPEs at the urban and rural sites and by nonchlorinated OPEs at the remote sites. The concentrations of all OPEs were significantly (P < 0.001) correlated to one another, suggesting that these compounds share similar sources. Most atmospheric ∑OPE concentrations were significantly (P < 0.05) decreasing over time, with halving times of about 3.5 years at the urban sites and about 1.5 years at the rural and remote sites. Interestingly, TCEP and EHDP concentrations were increasing over time at the rural and remote sites with doubling times of 2.2 and 3.7 years, respectively.

Precision of Atmospheric Persistent Organic Pollutant Concentration Measurements.

Environmental measurement programs are often undertaken with the assumption that measurements at a given location will be comparable to others that would be observed at the same time in the immediate vicinity, but this assumption has seldom been tested. This paper does so. We discuss here the precision of atmospheric concentration measurements of persistent organic pollutants (POPs) near the North American Great Lakes-measurements that we have been conducting since 1994. We report the relative percent differences between the measured values for 100-200 duplicate samples, and through our use of surrogate (recovery) standards, we have separated the analytical error from the sampling error for the target compounds. The error contributions we calculated were on the order of 5% for the analytical error and 20% for the sampling error, suggesting that the latter is the greatest hindrance to increased precision. In a comparison of relative percent differences for measurements among different atmospheric phases, we observed the highest errors for precipitation samples, with an average median of 35 ± 3, which is more than for vapor-phase samples (27 ± 3) or particle-phase samples (27 ± 2). We suggest that sampling errors are principally the result of inaccuracies in measuring the sample volume and possibly the result of spatial heterogeneity of the atmosphere.

Identification of Marbon in the Indiana Harbor and Ship Canal.

Marbon is isomeric with Dechlorane Plus (DP). Both are produced by the Diels-Alder condensation of hexachlorocyclopentadiene with cyclic dienes, and both have elemental compositions of C18H12Cl12. Dechlorane Plus is commonly found in the environment throughout the world, but Marbon has, so far, only been detected at low levels in one sediment core collected near the mouth of the Niagara River in Lake Ontario. Here we report on the concentrations of Marbon and anti-DP in 59 water samples from five Lake Michigan tributaries [the Grand, Kalamazoo, St. Joseph, and Lower Fox Rivers, and the Indiana Harbor and Ship Canal (IHSC)], 10 surface sediment samples from the IHSC, and 2 surface sediment samples from the Chicago Sanitary and Ship Canal. Three Marbon diastereomers were detected in the water and sediment samples from the IHSC, which is far from the location of its previous detection in Lake Ontario. The sum of the concentrations of the three Marbons was greater in the water from the IHSC (N = 11, median =150 pg/L) compared to those in water from the other four tributaries (N = 11-13, medians =0.9-2.0 pg/L). Marbon concentrations in sediment samples from the IHSC were up to 450 ng/g dry weight. Anti-DP was also measured for comparison. Its concentrations were not significantly different among the water samples, but its sediment concentrations in the IHSC were significantly correlated with those of Marbon. The source of Marbon contamination in the IHSC is not clear.

Locating POPs Sources with Tree Bark.

Locating sources of persistent organic pollutants (POPs) to the atmosphere can sometimes be difficult. We suggest that tree bark makes an excellent passive atmospheric sampler and that spatial analysis of tree bark POPs concentrations can often pinpoint their sources. This is an effective strategy because tree bark is lipophilic and readily adsorbs and collects POPs from the atmosphere. As such, tree bark is an ideal sampler to find POPs sources globally, regionally, or locally. This article summarizes some work on this subject with an emphasis on kriged maps and a simple power-law model, both of which have been used to locate sources. Three of the four examples led directly to the pollutant's manufacturing plant.

Variations of Flame Retardant, Polycyclic Aromatic Hydrocarbon, and Pesticide Concentrations in Chicago's Atmosphere Measured using Passive Sampling.

Atmospheric concentrations of flame retardants, polycyclic aromatic hydrocarbons, and pesticides were measured using passive air samplers equipped with polyurethane foam disks to find spatial information in and around Chicago, Illinois. Samplers were deployed around the greater Chicago area for intervals of 6 weeks from 2012 to 2013 (inclusive). Volumes were calculated using passive sampling theory and were based on meteorology and the compounds' octanol-air partition coefficients. Geometric mean concentrations of total polybrominated diphenyl ethers ranged from 11 to 150 pg/m3, and tributyl phosphate, tris(2-chloroethyl)phosphate, tris(1-chloro-2-propyl)phosphate, and triphenyl phosphate concentrations were in the ranges of 54-290, 32-340, 130-580, and 170-580 pg/m3, respectively. The summed concentrations of 16 PAHs ranged from 8700 to 52,000 pg/m3 over the sampling area, and DDT, chlordane, and endosulfan concentrations were in the ranges of 2.7-9.9, 8.2-66, and 16-85 pg/m3, respectively. Sampling sites were split into two groups depending on their distances from the Illinois Institute of Technology campus in Chicago. With a few exceptions, the concentrations of most compound groups in the city's center were the same or slightly higher than those measured >45 km away. The data also showed that the concentrations measured with a passive atmospheric sampling system are in good agreement with those measured with an active, high-volume, sampling system. Given that the sampling times are different (passive, 43 days; active, 1 day), and that both of these measured concentrations cover about 5 orders of magnitude, the agreement between these passive and active sampling methods is excellent.