The Permanent Senate Commission for the Investigation of Health Hazards of Chemical Compounds in the Work Area of the German Research Foundation (DFG) has presented the 57th so-called MAK and BAT Values List. The list contains 95 changes and new additions this year. The Senate Commission is organized in different working groups. IfADo is part of the Neurotoxicity and Sensory Working Group, which has been significantly involved in new limits for lead.
In the current list, the commission sets new assessments for lead and its inorganic compounds. Mainly due to the ban on leaded gasoline, the exposure of the general population in industrialized countries has decreased in recent decades. This is also reflected in continuously decreasing blood lead levels. However, lead is still a major problem in the workplace.
With the help of new findings on the carcinogenic effect and organ damage caused by lead, it was possible to change the previous classification from carcinogenicity category 2 (carcinogenic in animal experiments, no limit value possible) to category 4 (carcinogenic, mechanism known, limit value can be evaluated). Thus, a BAT value of 150 µg/l blood could be derived for lead, compliance with which protects against both the carcinogenic effect and damage to the nervous system.
BAT and MAK value defined for lead
Lead absorbed into the body is stored in the bones for many years and is detectable in the blood. Simple conversions from a concentration in the air at the workplace to the concentration in the blood of workers are not possible for lead. However, using complex mathematical modeling, a MAK value of 0.004 mg/m3 could be derived from the BAT value. However, due to the developmental inhibitory effect of lead on the nervous system, a risk to the unborn child in the womb must be assumed even if the BAT or MAK value is adhered to, so that lead was assigned to pregnancy group A.
Section I of the MAK and BAT values list also includes two new text passages: one on how to deal with the MAK values designed for eight hours in the case of regularly longer working hours. The other is a fundamentally revised and supplemented passage on how to deal with odor-intensive agents when setting limits.
In addition to the MAK (maximum workplace concentration) values that give it its name – the amounts of substances that do not cause long-term damage in the air at the workplace in the form of gas, vapor or aerosol – the MAK and BAT value list provide information on whether substances in the working area can cause cancer, damage germ cells or an unborn child during pregnancy, sensitize the skin or respiratory tract, or be absorbed through the skin in toxic amounts. It also indicates the concentrations of substances in the body to which a person can be exposed throughout his or her working life without causing damage to health (biological working substance tolerance values, BAT values). The list of MAK and BAT values also includes biological guide values (BLW) and occupational substance reference values (BAR). The so-called exposure equivalents for carcinogenic agents (EKA) show the internal exposure that would result if a substance were absorbed exclusively via the respiratory tract.