Week 11 Lecture: MMH2

Question 1

ACGIH TLV for lifting
- purpose
- items considered
- how to use it
- what are its limitations
- validity and reliability

Answer 1

Identifies safe loads (Threshold limit values, TLVs) in lbs for males and females to lift for different conditions
- considers frequency, duration, height of lift, horizontal distance travelled

How to use it
1. Determine task duration (cumulative)
2. Determine lifting frequency
3. Use TLV table corresponding to the duration and frequency of the task

• not for one-handed lifts or asymmetric lifts
• not for 2 person lifts
• must be les than 360 lifts per hour
• not for sitting or kneeling postures
• not for high heat or humidity conditions
• not for unstable objects or with poor handles
• not specifically for lowering
• does not consider anthropometry
• low to moderate validity
• moderate reliability

Question 2

MAC tool
- purpose
- limitations
- validity and reliability

Answer 2

• for lifting, carrying, team lifting
• considers many risk factors: Hand distances, vertical lift zones, twisting and side bending, constrained postures, grips, floor surfaces, environmental factors
• not for complex tasks
• requires training
• strong intra- to inter-rater reliability
• valid for risk identification but not risk assessment

Question 3

NIOSH lifting equation
- purpose
- equation
- limitations
- validity and reliability

Answer 3

• predicts recommended weight limit for 90% male population and 75% of female population
• Combines principles for biomechanical and physiological approaches to determine whether a lift or lower is safe

RWL=(LC)(HM)(VM)(DM)(AM)(FM)(CM)

• load constant (23kg)
• horizontal multiplier
• vertical multiplier
• distance multiplier
• asymmetry multiplier
• frequency multiplier
• coupling multiplier

not applicable to asks that involve
- pushing, pulling carrying, one handed lifts, unbalanced loads, slippery surfaces, hot environments, containers larger than 75cm in length

• high validity except at high and low frequencies
• older version is valid for more male dominated industries (even though it doesn’t take into account coupling
• good reliability

Question 4

What is Bakpak

Answer 4

• assessment tool that give you what % of population can do lift. also calculates disc compressive forces
• based on low back pain data collected by Potvin and some epidemiological data

Question 5

LM-MMH EQUATIONS
- developed why
- based on
- pros
- validity and reliability

Answer 5

• developed to replace liberty mutual tables
• based on a meta-analysis of 12 more publications + liberty mutual tables
• easier to use than tables and allows for a wider range of variables and more specific inputs
• good reliability and validity

Question 6

Composite lifting index
- what is it
- what does the index tell you
- limtiations

Answer 6

• cumulative version of NIOSH lifting equation
• estimate of the physical stress associated with overall lifting in work
• NIOSH recommends that the LI or CLI be equal to or lower than 1.0.

only for 2 handed tasks

Question 7

LIFFT
- what is it
- items
- validity and reliability

Answer 7

Cumulative low back loading limits for mono-tasks, multi-tasks and highly variable jobs using engineering principles

Items: weight of load, greatest horizontal distance, number of repetitions

• moderate to good validity for simple lifts
• good reliability

Question 8

How can we assess pushing and pulling tasks?

Answer 8

Liberty mutual equations and mital tables
- worksafebc push/pull calculators
- OHIO push/pull guides
- 3DSSPP

Question 9

How can we assess carrying tasks?

Answer 9

Liberty mutual and mital table
Worksafebc carry calculator
3DSSPP
LM-MMH
MAC