Low-level occupational exposure to BTEX and dyschromatopsia: a systematic review and meta-analysis

Objectives. The present study aimed to assess whether occupational exposure to low concentrations of benzene, toluene, ethylbenzene and xylene (BTEX) is associated with color vision impairment. Methods. We queried PubMed, Scopus, Embase, Web of Science and ProQuest as the main databases, as well as gray literature such as Google Scholar. A random-effects model was used to assess relative risk. A funnel plot was created to assess publication bias. Meta-regression analysis was applied to identify variables that explain the between-study variation in the reported risk estimate. Results. An overall standardized mean difference of 0.529 (95% confidence interval [0.269, 0.788]; p Conclusions. The impairments can occur even at exposures lower than the occupational exposure limits of BTEX. However, there are several flaws in the determination of workers’ exposure, which did not allow to establish how low a level of these chemicals can cause color vision impairment. </p

Baseline characteristics of patients with CVD at time of diagnosis.

<p>Baseline characteristics of patients with CVD at time of diagnosis.</p

Age-standardised prevalence of comorbidities in women and men.

<p>The top 20 comorbidities ranked by sex-specific age-standardised prevalence between 2000 and 2014 are shown for men (blue) and women (red). CKD, chronic kidney disease; COPD, chronic obstructive pulmonary disease; PAD, peripheral arterial disease.</p

Annual crude and age/sex-standardised prevalence of number of comorbidities in incident cardiovascular disease patients.

<p>(A) Crude prevalence. (B) Age/sex-standardised prevalence. Number labels for each line refer to the number of comorbidities.</p

Annual prevalence of the 10 most common comorbidities in patients with incident cardiovascular disease between 2000 and 2014.

<p>CKD, chronic kidney disease.</p

Age/sex-standardised prevalence of number of comorbidities in patients with incident cardiovascular disease by socioeconomic status.

<p>Socioeconomic status is split by quintiles of the Index of Multiple Deprivation for 2015, where 1 = the least deprived fifth, and 5 = the most deprived fifth.</p

Age-specific ranking of the top 10 most prevalent comorbidities.

<p>Age-specific ranking of the top 10 most prevalent comorbidities.</p

Age/sex-standardised prevalence of comorbidities in patients with incident cardiovascular disease (<i>n =</i> 229,205).

<p>Age/sex-standardised prevalence of comorbidities in patients with incident cardiovascular disease (<i>n =</i> 229,205).</p

Comorbidities selected.

<p>Comorbidities selected.</p

Annual age/sex-standardised incidence of CVD, IHD, and stroke/TIA.

<p>Overall CVD (red line); IHD (including acute myocardial infarction and angina; green line); stroke/TIA (blue line). CVD, cardiovascular disease; IHD, ischaemic heart disease; TIA, transient ischaemic attack.</p