Maximum end expiratory eNO was measured in each child with a fast response chemiluminescence analyzer. They found no effect of formaldehyde on lung function. However, controlling for age and atopy , eNO was significantly elevated to 15.5 ppb in homes with ≥ 50 ppb formaldehyde compared with 8.7 ppb eNO in homes with < 50 ppb formaldehyde. Authors did not report the cross-sectional risk of atopy to common allergens from exposure to formaldehyde. They hypothesized that formaldehyde causes inflammation and the release of cytokines, which leads to the upregulation of inducible NO synthetase. This view was supported by another study that found intranasal exposure to 400 ppb formaldehyde in healthy subjects caused eosinophilia in the nasal epithelium . Given that a key marker of the asthmogenic effects of formaldehyde may be specific IgE to formaldehyde-albumin, other air toxics could be similarly screened to evaluate their potential influence on atopic responses. Some experimental evidence in controlled human exposure studies supports an respiratory irritant mechanism for VOCs , but the human experimental research on lower respiratory or pulmonary immunologic effects of VOCs is scarce apart from studies of agents associated with occupational asthma . Koren et al. conducted a randomized crossover chamber study of 14 healthy nonsmoking young adult men. Subjects were exposed for 4 hr 1 week apart to clean air and 25 µg/m3 of a VOC mixture typical of indoor nonindustrial micro-environments. Nasal lavage performed immediately after exposure and 18 hr later showed significant increases in neutrophils at both time points. Harving et al. conducted a randomized crossover chamber study of 11 asthmatic individuals who were hyper reactive to histamine. Subjects were exposed for 90 min, 1 week apart to clean air and VOC mixtures at 2.5 and 25 µg/m3. Investigators found FEV1 decreased to 91% of baseline with 25 µg/m3,cannabis trimming but this was not significantly different from sham exposure, and there was no change in histamine reactivity.
It is possible that the null results do not reflect inflammatory changes that influence small airways, which could be missed with FEV1 measurements. What may be occurring in natural environments is another story, with mixed exposures possibly interacting under a wide range of exposure–dose conditions. This is best investigated with epidemiologic designs.Indirect evidence of a role for ambient VOCs in asthma comes from research linking a buildup of indoor irritants including VOCs and bio-aerosols in office buildings to a nonspecific cluster of symptoms called the “sick building syndrome,” which includes upper and lower respiratory tract symptoms, eye irritation, headache, and fatigue. Other studies have also found new-onset asthma occurring in relation to particular nonresidential indoor environments, especially where problems with ventilation systems or dampness have been found . It is possible that fungal spores or other aeroallergens, mycotoxins, and endotoxins could increase in parallel with VOCs under conditions of inadequate air exchange at work, and be responsible for some of these findings. Epidemiologic evidence linking indoor home VOCs with asthma or related respiratory outcomes come largely from cross-sectional studies. A survey of 627 students 13–14 years of age attending 11 schools in Uppsala, Sweden, showed self-reported asthma prevalence was higher in schools with higher VOCs . Other risk factors were not controlled for in this association. In addition, passive, not active, VOC measurements were associated with asthma. Norbäck et al. , using a survey sample of 600 adults 20–44 years of age in Uppsala, Sweden, selected a nonrandom sub-sample of 47 subjects reporting asthma attacks or nocturnal breathlessness the last 12 months or reporting current use of asthma medications. A random sub-sample of 41 other subjects was selected from the survey pool with negative responses. Logistic regression models adjusted for age, sex, smoking, carpeting, and house dust mites, but not dampness, which was significant. There were no effects on daytime breathlessness from concentrations of 2-hr active VOC samples in the homes. Nocturnal breathlessness was associated with toluene, C8-aromatics, terpenes, and formaldehyde in adjusted models. Bronchial hyper responsiveness was correlated only with limonene. PEF variability was correlated only with terpenes. Wieslander et al. aimed to examine respiratory symptoms and asthma outcomes in relation to indoor paint exposures in thelast year.
They selected an enriched random sample of 562 adult subjects, including asymptomatic responders along with all reporting asthma or nocturnal dyspnea , using the same survey source population as Norbäck et al. in Uppsala. Asthma was defined as positive bronchial hyper responsiveness to methacholine plus asthma symptoms . Thirty-two percent of homes and 23% of workplaces were painted within the last year. Total VOC was elevated by 100 µg/m3 in 62 newly painted homes. Logistic regression models adjusted for age, sex, and current smoking but not ETS. Asthma prevalence was greater for newly painted homes [OR 1.5 ], consistent with greater differences in VOCs . Blood eosinophil concentrations were also elevated in newly painted homes. In newly painted workplaces, asthma like symptoms were significantly increased , but there was no association with bronchial hyper responsiveness or eosinophils. There were no associations for newly painted homes or workplaces and atopy , serum eosinophilic cationic protein, serum IgE, PEF variability , or in-clinic FEV1. Biases in the above cross-sectional studies in Uppsala include potential selection bias and the possibility that health outcomes preceded exposures. Diez et al. studied 266 newborn children born with birth weight of 1,500–2,500 g, or with elevated IgE in cord blood, or with a positive primary family history of atopic disease. Concentrations of 25 VOCs were monitored indoors during the first 4 weeks of life. Parents filled out questionnaires after 6 weeks and 1 year of age. Postnatal respiratory infections were associated with benzene > 5.6 µg/m3 [OR 2.4 ] and styrene > 2.0 µg/m3 [OR 2.1 ]. Wheezing was associated with reports of restoration during the first year of life, but not with total or specific IgE at the age of 1 year. These models controlled for heating, gas cooking, home size, new furniture, and animals but did not control for significant effects of ETS, which was correlated with benzene. All of the above studies of indoor VOCs may be subject to unmeasured confounding by other causal agents that increase indoors under low ventilation conditions, including aeroallergens, or that are correlated with VOCs for other reasons. Most, but not all, of the studies controlled for ETS. The research to date is too sparse to evaluate causality from indoor home VOCs,rolling benches but there is even less information to evaluate the public health impact on respiratory health from outdoor VOCs, which include some of the same compounds found indoors. Ware et al. conducted a study in a large chemical manufacturing center in the Kanawha Valley, West Virginia. They surveyed 74 elementary schools with interviews of 8,549 children in and out of the valley and measured passive 8-week samples of 5 petroleum-related VOCs and 10 process related VOCs . Higher VOC concentrations were found in the valley.
Cross-sectional results showed children in the valley had higher rates of physician-diagnosed asthma [OR 1.27 ]. Composite indicators for lower respiratory symptoms in the last year were weakly positively associated with petroleum-related VOC levels [OR per 10 µg/m3, 1.05 ] and process-related VOCs levels [OR per 2 µg/m3, 1.08 ]. Asthma diagnoses were weakly positively associated with petroleum-related VOCs [OR 1.05 ] but not process related VOCs . One school with high petroleum-related VOCs strongly influenced the model. The average concentrations measured in the Kanawha study do not differ greatly from average levels in large urban areas . For the Kanawha study compared with a Los Angeles ambient exposure study, for example, average toluene was 9.7 µg/m3 versus 13 µg/m3, respectively, and for benzene, 3.2 µg/m3 versus 3.5 µg/m3, respectively . In a study of 51 residents of Los Angeles, personal and indoor air concentrations of all prevalent VOCs except carbon tetrachloride were higher than outdoor ambient concentrations . Also, personal real time exposures can be even higher, particularly while in cars . For example, measurements of toluene taken inside cars in New York City ranged from 26 to 56 µg/m3 and for benzene ranged from 9 to 11 µg/m3 . Assessing the environmental impacts of the cannabis industry in Northern California has been notoriously difficult . The federally illegal status of cannabis has prevented researchers from obtaining funding and authorization to study cultivation practices . Fear of federal enforcement has also driven the industry into one of the most sparsely populated and rugged regions of the state , further limiting opportunities for research. The result has been a shortage of data on cultivation practices and their environmental risks .Given the propensity of cannabis growers to establish farms in small, upper watersheds, where streams that support salmonids and other sensitive species are vulnerable to dewatering , significant concerns have been raised over the potential impacts of diverting surface water for cannabis cultivation. The environmental impacts of stream diversions are likely to be greatest during the dry summer months , which coincide with the peak of the growing season for cannabis. Further, because cannabis cultivation operations often exhibit spatial clustering , some areas with higher densities of cultivation sites may contain multiple, small diversions that collectively exert significant effects on streams .
An important assumption underlying these concerns, however, is that cultivators rely primarily on surface water diversions for irrigation during the growing season. Assessments of water use impacts on the environment may be inaccurate if cultivators in fact use water from other sources. For instance, withdrawals from wells may affect surface flows immediately, after a lag or not at all, depending on the well’s location and its degree of hydrologic connectivity with surface water sources . Documenting the degree to which cannabis cultivators extract their water from above ground and below ground sources is therefore a high priority. In 2015, the North Coast Regional Water Quality Control Board , one of nine regional boards of the State Water Resources Control Board, developed a Cannabis Waste Discharge Regulatory Program to address cannabis cultivation’s impacts on water, including stream flow depletion and water quality degradation. A key feature of the cannabis program is an annual reporting system that requires enrollees to report the water source they use and the amount of water they use each month of the year. Enrollees are further required to document their compliance status with several standard conditions of operation established by the cannabis program. These include a Water Storage and Use Condition, which requires cultivators to develop off-stream storage facilities to minimize surface water diversions during low flow periods, among other water conservation measures. Reports that demonstrate noncompliance with the Water Storage and Use Standard Condition indicate that enrollees have not yet implemented operational changes necessary for achieving regulatory compliance. In this research, we analyzed data gathered from annual reports covering 2017 to gain a greater understanding of how water is extracted from the environment for cannabis cultivation. The data used in this study was collected from cannabis sites enrolled for regulatory coverage under the cannabis program. The program was adopted in August 2015, with the majority of enrollees entering the program in late 2016 and early 2017. The data presented in this article was collected from annual reports submitted in 2018 , which reflected site conditions during the 2017 cultivation year. The data therefore represents, for the majority of enrollees in the cannabis program, the first full season of cultivation regulated by the water quality control board. Because the data was self-reported, we screened reports for quality and restricted the dataset to reports prepared by professional consultants. Most such reports were prepared by approved third-party programs that partnered with the board to provide efficient administration of, and verification of conformity with, the cannabis program. Additional criteria for excluding reports included claims of applying water from storage without any corresponding input to storage, substantial water input from rain during dry summer months and failure to list a proper water source. Reports containing outliers of monthly water extraction amounts were also identified and excluded due to the likelihood of erroneous reporting or the difficulty of estimating water use at very large operations.