Club cell protein (CC16) in serum as an effect marker for small airway epithelial damage caused by diesel exhaust and blasting fumes in potash mining

OBJECTIVE

The effect marker club cell protein (CC16) is secreted by the epithelium of the small respiratory tract into its lumen and passes into the blood. Increased amounts of CC16 in serum are observed during acute epithelial lung injury due to air pollutants. CC16 in serum was determined as part of this cross-sectional study in underground potash miners on acute and chronic health effects from exposures to diesel exhaust and blasting fumes.

METHODS

Nitrogen oxides, carbon monoxide, and diesel particulate matter were measured in 672 workers at a German potash mining site on a person-by-person basis over an early shift or midday shift, together with CC16 serum concentrations before and after the respective shift. CC16 concentrations and CC16 shift-differences were evaluated with respect to personal exposure measurements and other quantitative variables by Spearman rank correlation coefficients. CC16 shift-differences were modeled using multiple linear regression. Above-ground workers as reference group were compared to the exposed underground workers.

RESULTS

Serum concentrations of CC16 were influenced by personal characteristics such as age, smoking status, and renal function. Moreover, they showed a circadian rhythm. While no statistically significant effects of work-related exposure on CC16 concentrations were seen in never smokers, such effects were evident in current smokers.

CONCLUSION

The small airways of current smokers appeared to be vulnerable to the combination of measured work-related exposures and individual exposure to smoking. Therefore, as health protection of smokers exposed to diesel exhaust and blasting fumes, smoking cessation is strongly recommended.

Impact of diesel exhaust exposure on urinary 1-hydroxypyrene in underground salt and potash workers

BACKGROUND

Diesel engine exhaust (DEE) and some of the polycyclic aromatic hydrocarbons (PAH) it contains are carcinogenic to humans (for example benzo(a)pyrene) and can cause lung cancer in workers. The objective of this study was to assess exposures to DEE and its component PAH and the potential associations between these two health hazards in a salt and potash mining population.

METHODS

Between 2017 and 2019, 1003 underground workers (mining n = 801, maintenance n = 202) and 243 above-ground facility workers from two German mines participated. Personal exposure to DEE was assessed in air as elemental carbon for diesel particulate matter (EC-DPM), whereas exposure to PAH was assessed in pre- and post-shift urine samples in terms of 1-hydroxypyrene (1-OHP). Associations between EC-DPM and 1-OHP were studied using linear regression models.

RESULTS

The highest EC-DPM exposures were measured in mining workers (median 0.06 mg/m³) followed by workers in the maintenance (0.03 mg/m³) and facility areas (<0.02 mg/m³). Exposures above the current German occupational threshold level of 0.05 mg/m³ were observed in 56%, 17%, and 5% of mining, maintenance and facility workers, respectively. 1-OHP increased statistically significantly across a work shift in underground workers but not in facility workers. Regression analyses revealed an increase of post-shift 1-OHP by almost 80% in mining and 40% in maintenance compared with facility workers. 1-OHP increased with increasing EC-DPM among underground workers. However, internal exposure of 1-OHP mainly remained at levels similar to those of the German general population in more than 90% of the urine samples.

CONCLUSIONS

While exposures to DEE above the current German OEL for EC-DPM are quite common in the studied population of underground salt and potash miners (39.5% overall), urinary concentrations of 1-OHP did not reflect these findings.

Underground salt and potash workers exposed to nitrogen oxides and diesel exhaust: assessment of specific effect biomarkers

Purpose

Occupational exposure limits (OEL) for nitrogen oxides (NO, NO₂) and diesel exhaust (EC-DPM) were reassessed by the German authorities in 2016/2017. We performed a clinical cross-sectional study among salt and potash underground workers exposed to these substances at relatively high levels to examine possible indicators of acute effects on workers’ health.

Methods

We measured post- versus pre-shift differences in cardiovascular, inflammatory, immune, and respiratory effect biomarkers and assessed their associations with personal exposures measured during the same shift. We also compared post- versus pre-shift differences in biomarker levels between exposure groups defined based on work site and job type.

Results

None of the above-ground workers exceeded the OEL for NO₂ and only 5% exceeded the OEL for EC-DPM exposure. Among underground workers, 33% of miners and 7% underground maintenance workers exceeded the OEL for NO₂; the OEL for EC-DPM was exceeded by 56% of miners and 17% of maintenance workers.

Some effect biomarkers (thrombocytes, neutrophils, MPO, TNF-α, IgE, FeNO) showed statistically significant differences between pre- versus post-shift measurements; however, there were no consistent associations between pre- and post-shift differences and exposure group or personal exposure measurements during the shift.

Conclusions

We did not find evidence of associations between workplace exposure to NO, NO₂ or EC-DPM and clinically relevant indicators of acute cardiovascular, inflammatory and immune, or respiratory effects among salt and potash underground workers in Germany.

Supplementary Information

The online version contains supplementary material available at 10.1007/s00420-022-01876-2.

Improved carrier-envelope phase locking of intense few-cycle laser pulses using above-threshold ionization

A robust nonoptical carrier-envelope phase (CEP) locking feedback loop, which utilizes a measurement of the left-right asymmetry in the above-threshold ionization (ATI) of Xe, is implemented, resulting in a significant improvement over the standard slow-loop f-to-2f technique. This technique utilizes the floating average of a real-time, every-single-shot CEP measurement to stabilize the CEP of few-cycle laser pulses generated by a standard Ti:sapphire chirped-pulse amplified laser system using a hollow-core fiber and chirped mirror compression scheme. With this typical commercially available laser system and the stereographic ATI method, we are able to improve short-term (minutes) CEP stability after a hollow-core fiber from 450 to 290 mrad rms and long-term (hours) stability from 480 to 370 mrad rms.

[Hemodynamics, plasma catecholamine behavior and beta-adrenergic receptor density in trained and untrained subjects and cardiac insufficiency patients]

Swan-Ganz semifloating balloon-tipped catheters were introduced in 6 endurance-trained subjects, 7 untrained volunteers, 29 patients suffering from coronary heart disease, 8 patients with right heart insufficiency induced by chronic obstructive syndromes, and 8 patients with idiopathic congestive cardiomyopathy. All subjects except the patients with resting cardiac insufficiency performed graded ergometric tests during the catheter investigation. Hemodynamic values, plasma noradrenaline and adrenaline (in all subjects), and beta-adrenergic receptor density on intact polymorphonuclear leucocytes (in 6 endurance-trained subjects, 5 untrained healthy volunteers, and 6 patients with left heart insufficiency) were determined. For all subjects investigated, significant correlations were observed between resting plasma catecholamine levels and resting hemodynamic values, such as stroke volume (r = 0.47, p less than 0.001), cardiac output (r = 0.32, p less than 0.05), heart rate (r = 0.37, p less than 0.01), pulmonary vascular resistance (r = 0.52, p less than 0.001), and total vascular resistance (r = 0.40, p less than 0.01). An inverse relationship existed between the resting catecholamine levels and the performance ability. Catecholamine levels were approximately three- to fourfold higher and the beta-adrenergic receptor density approximately two- to threefold lower in patients with left heart insufficiency than in healthy untrained subjects. The plasma catecholamine levels were lower and the beta-adrenergic receptor density approximately 60% greater in trained subjects. The beta-adrenergic receptor density may be a critical dynamic parameter for the modulation of sympathetic effects.