(1) Background: To estimate the cumulative exposure to respirable crystalline silica (RCS) that reduces lung function to an extent corresponding with airway obstruction equivalent to chronic obstructive pulmonary disease (COPD). (2) Methods: The study is based on a miners’ cohort with longitudinal data on lung function and RCS exposure. Random-effects linear regression models, allowing for a possible threshold concerning the exposure concentration were used to analyze the impact of RCS on the ratio of forced expiratory volume in 1 s and forced vital capacity (FEV₁/FVC). The proposed threshold is the amount of RCS resulting in a decrease in FEV₁/FVC from the expected value to the lower limit of normal. (3) Results: The analysis shows that a threshold model fits the data significantly better than the usual linear model. The estimated threshold value for the exposure concentration is 0.089 mg/m³. Using this threshold, the estimate for the corresponding reference dose for RCS is 2.33 mg/m³·y. (4) Conclusions: The analysis confirmed that RCS has a negative impact on lung function. The effect is primarily due to exposure above a concentration threshold of 0.1 mg/m³. It is recommended that COPD should be compensated as an occupational disease if cumulative exposure was at least 2 mg/m³·y above this threshold.

中文翻译：

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基于肺功能的纵向变化估算二氧化硅诱导的COPD的暴露阈值。

（1）背景：评估累积暴露于可呼吸的结晶二氧化硅（RCS）中，该物质可将肺功能降低至与慢性阻塞性肺疾病（COPD）相当的气道阻塞。（2）方法：该研究基于矿工的队列研究，该队列具有关于肺功能和RCS暴露的纵向数据。使用随机效应线性回归模型（允许有关暴露浓度的可能阈值）来分析RCS对1秒钟呼气量与强制肺活量（FEV ₁ / FVC）之比的影响。提议的阈值是导致FEV ₁降低的RCS数量/ FVC从期望值到正常下限。（3）结果：分析表明，阈值模型对数据的拟合明显优于常规线性模型。暴露浓度的估计阈值为0.089 mg / m ³。使用该阈值，RCS相应参考剂量的估计值为2.33 mg / m ³ ·y。（4）结论：分析证实RCS对肺功能有负面影响。该影响主要是由于暴露于浓度阈值0.1 mg / m ^3以上。如果累积暴露量至少超过此阈值2 mg / m ³ ·y，建议将COPD作为职业病进行补偿。