We provide a broad-base of services within the realm of assessing the risk of chemicals to human health, our specialty is the estimation of previous, present and future human exposure (and then risk) from chemical emission and contact.  Along with this we have over a decade of experience in determining C,t Probit expressions for lethality from toxicological data.


Human Health Risk Assessment from Substances


Estimation of human health risk (RA) from exposure to substances occurring during normal human contact. I have over 25 years’ experience in determining human health exposure assessment (EA) or risk assessment (RA) from exposure to chemical and physical agents. Risk assessment (RA) comes from the integration of exposure assessment (EA) and information on the inherent toxicity of the substance (TOX).   

                                                RA = f (EA) (TOX)

  • Comparison of estimated exposure (EXP) to exposure limits (EL) to render a hazard index or HI = EXP/EL for the exposures under consideration.
  • Estimation of a working exposure limit (EL) based on available toxicological information.
  • Estimation of human dose response function for comparison to the estimated exposure (EXP) to render a quantitative estimation of risk (i.e., probability of an individual response or proportion of exposed population responding).





Use of animal and typically meager human  toxicological data to predict lethality from inhalation exposure to acute toxicants of short duration. 

                                               Y = a + b ln(((Cexp n)(t))

  • Y equal Probit of predicted responders with Y = 5 at 50% and Y = 6 at 85%
  • C = Concentration in air for time (t)
  • a and b are coefficients.
  • Cexp n is C to the n power.



Exposure and Dose-Response Estimation through Mathematical Modeling

  • Mathematical modeled estimation of inhalation,  dermal or oral exposure potential (EXP) based on reasonably determined exposure scenarios.
  • Mathematical model estimation of human dose-responsefunction based on available toxicological data.
    • Response as a function of varying exposure during and after a constant time
    • Response as a function of varying exposure and time (C,t) probit analysis for short term events.
  • Statistical analysis of monitoring data to estimate exposure (EXP).


Other Services

Assessment of Exposures that Occurred in the Past


Retrospective exposure assessment in support of litigation or for the development of exposure limits based on documented adverse human health effects occurring from exposure.


Uncertainty Analysis

  • Quantitative Uncertainty analysis of the above determinations to assist the client in determining the driving determinants, true risk and next steps.

Investigation of  unexplained illness or symptoms within the workplace or home

  • experience in investigating and tracking down and recommending controls for the sources of significant chemical exposure within the workplace or residences

Education and Mentoring  of Young Professionals

  • Instruction, mentoring and collaboration on specific and relevant projects leading to a successful project completion and an educated staff member.