Number of workers employed by the U.S. oil and gas extraction industry: 435,000

Percent of those workers employed by well servicing companies, including those that conduct hydraulic fracturing or "fracking" for natural gas: almost 50

Occupational deaths in the oil and gas extraction industry from 2003 to 2003 2009 per 100,000 workers: 27.5

Number of times that rate exceeds the fatality rate for all U.S. workers: more than 7

Percent by which fatalities among oil and gas workers rose from 2003 to 2005, as the drilling boom accelerated: 15

Rank of highway crashes among the top causes of fatalities in the industry: 1

Number of oil and gas workers killed in highway crashes over the past decade: more than 300

Of the 648 oil and gas field worker deaths from 2003 to 2008 alone, portion that were due to highway crashes: 1/3

Portion of workplace fatalities accounted for by highway crashes across all industries in 2010: 1/5

Length of shifts in hours that oil and gas field workers are routinely pressured into working by employers who cite longstanding regulatory exemptions enjoyed by the industry: 20

The legal limit of workshifts for most commercial truckers, in hours: 14

Of the 2,200 oil and gas industry trucks inspected from 2009 to February 2012 by state police in Pennsylvania, the epicenter of the fracking boom, percent that were in such poor condition they had to be taken off the road: 40

Number of fracking sites where the National Institute for Occupational Safety and Health (NIOSH) recently collected air samples to evaluate worker exposure to crystalline silica, which is present in the "frac sand" used in the natural gas extraction process and causes silicosis (shown in X-ray above), an incurable lung disease: 11

Percent of the tested fracking sites where workers' exposure to respirable crystalline silica exceed occupational health limits: 100

Percent of crystalline silica that typically makes up "frac sand": 100

Pounds of sand typically used to frack a single well: up to 4 million

Percent of the 116 air samples collected that exceeded the NIOSH recommended exposure limit by a factor of 10 or more, rendering the use of half-mask air-purifying respirators insufficiently protective: 31

Date on which two workers were hurt in an explosion at a fracking tank site in Texas: 5/16/2012

Number of months before the explosion that the site's owner, Vann Energy Services LLC, was cited for 17 serious health and safety violations: 3

Date on which the AFL-CIO wrote a letter to federal labor officials expressing concern about serious safety and health risks faced by workers in the fracking industry and calling for better protections: 5/22/2012

Percent change in the number of drilling rigs from 2010 to 2011: +22

Percent change in the number of inspections at those work sites: -12

(Click on figure to go to source. X-ray showing lungs affected by silicosis by Gumersindorego via Wikipedia.)